Pain After Surgery and CBD Oil: Research and Doses

What does the research say?

CBD and CBD-rich extracts have been tested for low back pain in the emergency department, after a kidney stone procedure, after root canal treatment, and after knee replacement surgery (applied to the skin). In none of these studies did CBD reduce pain more than placebo. In 36 patients who had both knees replaced at once, CBD taken by mouth also did not significantly reduce the amount of opioids used in the 72 hours after surgery compared with placebo; the reduction seen in the 400 mg group appeared only in an additional analysis done afterwards, and at 800 mg side effects and anxiety scores increased. An 8-person pilot study after tooth extraction gave only descriptive results because the number of participants was so small.

In a study after keyhole shoulder surgery (arthroscopy), people who took CBD had slightly less pain only on the first day; there was no difference on the following days and opioid use did not change. At the one-year follow-up there was also no difference in pain or shoulder function. A small study in emergency dental pain reported a positive result with very high single doses; however, drowsiness, diarrhea and abdominal pain were also more common at these doses.

In 35 people who had eye laser surgery (PRK), one eye was treated with CBD and the other with a painkiller containing codeine and acetaminophen (paracetamol); pain was similar in the two periods. However, because this study had no inactive substance (placebo) group, it is not possible to know how much CBD reduced pain.

In healthy volunteers given experimental pain, even high single doses had no effect. 50 mg of CBD did not change how intense the pain was, only how much it bothered people; the same reduction was also seen in sessions where no CBD was given and people were only told "you received CBD" (an expectation effect). CBD given together with an opioid slightly increased the opioid's effect on some pain measures, but not on the main measure set in advance; side effects were more common at 100 and 200 mg. Adding 10–450 mg of CBD to THC did not increase THC's pain-relieving effect; 450 mg of CBD increased the feeling of being high. In a meta-analysis that combined 18 experimental pain studies of cannabis and THC-like drugs, the pain threshold rose slightly, but pain intensity did not decrease. An analysis that pooled cannabis products for postoperative pain, most of them containing THC, also found no difference in opioid use or in pain at 24 hours; at 12 hours pain was slightly worse and drops in blood pressure were more common.

THC-containing products (dronabinol, THC by mouth or by IV, and a cannabis oil that was mainly CBD but also contained THC) and the THC-like drug nabilone were tested for postoperative and acute pain in eight placebo-controlled studies: uterine and prostate surgery, various major operations, tooth extraction, medication abortion, and three knee replacement studies (two published in 2026; 111 and 163 patients). None clearly reduced pain or the need for opioids; with high-dose nabilone, pain scores were even higher than with placebo. Most of these studies were small and the THC doses were low, so the evidence for THC is also weak. In an open-label trial of 469 patients hospitalized for trauma, the daily amount of opioids was similar in those who took dronabinol and those who did not (results only in the registry, with no statistical comparison). The studies that reported a benefit had no placebo: an open-label trial of 68 patients having coronary bypass surgery (40% less opioid use), an uncontrolled dose-escalation study, and two retrospective comparisons.

Nausea and vomiting after surgery: nabilone (two studies), dronabinol (one study) and IV THC (one study), given before or at the end of surgery, did not reduce nausea and vomiting more than placebo or standard anti-nausea medicines (metoclopramide, ondansetron). In the largest study, with 340 patients (a single low dose of nabilone before surgery), the rate of nausea and vomiting was about 21% in both groups. The IV THC study was stopped early because THC was found ineffective and because of side effects such as drowsiness and confusion. At one breast surgery center where dronabinol was given together with another anti-nausea medicine, nausea fell markedly; however, this was a retrospective comparison that could not separate the effects of the two drugs. No results were found for a registered study of pure CBD. The strength of evidence for nausea is weak.

People who used cannabis regularly before surgery: in a review summarizing 42 observational studies on this topic, among the studies that measured pain, 14 found more postoperative pain in cannabis users and 10 found no difference; the need for opioids was higher in 18 studies and no different in 17. In a study of 27,000 patients, daily users had a slightly higher risk of nausea and vomiting after surgery (relative risk 1.19). For this reason, the American (ASRA 2023) and Canadian (PAIN 2021) guidelines recommend asking about cannabis use before surgery and being prepared for a possibly greater need for pain medicine.

Strength of evidence: ●●○○ Weak evidence. Finding: No effect found. What does this mean?

Ongoing research on this topic

Trials testing CBD for this topic on ClinicalTrials.gov: 3 under way (3 recruiting). A trial being under way does not show that CBD works.

NCT06234631: Phase 2, recruiting, target 380 participants
NCT06448923: Phase 2, recruiting, target 225 participants
NCT06381791: Phase 1/2, recruiting, target 80 participants

Registries in other countries also list 1 recruiting trial on this topic: other registries.

All trials on this topic and their history

Possible side effects and drug interactions

In the dental pain study, drowsiness, diarrhea and abdominal pain were more common at high doses in people taking CBD. A single dose caused a small drop in blood pressure; drops in blood pressure after surgery were reported more often with THC-containing products. In patients who had both knees replaced at once, side effects and anxiety scores were higher with 800 mg of CBD. One nausea study of IV THC was stopped early because of drowsiness and confusion as well as lack of effect; with high-dose nabilone, pain scores after surgery were higher than with placebo.

CBD can slow the breakdown of some medicines in the body; this matters especially around the time of surgery. In one patient taking warfarin, the blood clotting value (INR) rose; the effect of the blood thinner clopidogrel may be reduced. Drowsiness may increase when CBD is combined with opioids, gabapentin, pregabalin or sleep medicines. Raised liver enzymes were more common when high-dose CBD was used together with acetaminophen (paracetamol).

Interactions with medicines used for this condition

Interactions reported for these medicines in peer-reviewed publications and official prescribing information. A medicine that is not listed can still interact with CBD; tell your doctor about every medicine you take.

Pain After Surgery: medicines used and their interactions with CBD
Medicine	Importance	Warning	Source
Warfarin	High importance	Warfarin: If you take warfarin, tell your doctor before starting CBD. Case reports have described INR rising and the warfarin dose needing to be lowered; more frequent INR monitoring is recommended.	PMID 29387536, PMID 33016308, PMID 30326170
Other opioids (morphine, oxycodone, fentanyl, tramadol, etc.), Methadone	Caution	Methadone and other opioids: In a child, a high methadone level was found and drowsiness developed while CBD was being used; two weeks after CBD was stopped, the level fell to less than half and the symptoms resolved. In small controlled studies with morphine and buprenorphine, no clear change in drug levels was seen; with a single intravenous dose of fentanyl, there was no respiratory depression. Drowsiness may increase together with opioids. Tell the doctor who manages your pain or addiction treatment.	PMID 32444381, PMID 41622700, PMID 41467610, PMID 25748562, FDA Epidiolex label §7.4 (05/2026)
Gabapentin (Gabateva, Neruda), Pregabalin (Lyrica)	Caution	Benzodiazepines, sleep medicines and sedatives: Drowsiness and sedation may increase together with CBD. Talk to your doctor before using them together.	DailyMed Epidiolex label 7.4, EMA Epidyolex SmPC 4.4
Acetaminophen (paracetamol)	Caution	Acetaminophen and the liver: In a knee osteoarthritis study, liver enzyme elevations were more common in people taking 600 mg of CBD together with 3 g a day of acetaminophen (paracetamol) than with placebo (15 vs. 5 patients). Enzyme elevations were also seen in healthy adults at a lower CBD dose (5 mg/kg a day). If you take acetaminophen regularly, talk with your doctor about liver tests.	PMID 38033459, PMID 40622698
Tizanidine	Caution	Theophylline, tizanidine: CBD can raise the blood levels of these medicines; the prescribing information for approved CBD recommends considering a dose reduction. The tizanidine prescribing information itself asks that it not be combined with weak CYP1A2 inhibitors such as CBD; low blood pressure, a slowed heart rate or excessive drowsiness may occur. Tell your doctor.	FDA Epidiolex label §7.2 (05/2026), EMA Epidyolex SmPC 4.5, PMID 33951339, Tizanidine prescribing information §7.2, dailymed.nlm.nih.gov
Clopidogrel	Caution	Clopidogrel: If you take clopidogrel, talk to your doctor. The drug's package leaflet states that CBD may reduce the effectiveness of this medicine; no clinical cases have been reported.	dailymed.nlm.nih.gov
Apixaban (DOAC), Rivaroxaban (DOAC)	Information	DOAC blood thinners: If you take a blood thinner, tell your doctor about CBD. There are no clinical data on interactions between these medicines and CBD; there is only a general warning in the package leaflet.	dailymed.nlm.nih.gov
NSAIDs (ibuprofen, naproxen, celecoxib, etc.)	Information	NSAID pain relievers: There is no documented meaningful interaction between CBD and these pain relievers; there are no direct studies either. The bleeding and kidney risks come from the NSAID itself.	FDA Epidiolex label §12.3 (05/2026), Celecoxib prescribing information §7, dailymed.nlm.nih.gov

To check interactions with the medicines you take: CBD drug interaction checker.

How was CBD used in studies?

In studies of postoperative and acute pain, pure CBD was used at doses from 20 mg a day (study dose; not a personal recommendation) up to 800 mg per dose (study dose; not a personal recommendation). The shoulder surgery study gave 75–150 mg a day based on body weight (study dose; not a personal recommendation), and the dental pain study gave a single dose of 10 or 20 mg for each kilogram of body weight (study dose; not a personal recommendation). In patients who had both knees replaced at once, 400 or 800 mg (study dose; not a personal recommendation) was tried four times around surgery; side effects increased at 800 mg. No consistent benefit was shown at these doses.

Study details (for health professionals)

Most RCTs of pure CBD showed no superiority over placebo: low back pain in the emergency department, ureteroscopy, root canal treatment and total knee replacement (topical). In shoulder arthroscopy there was a difference in pain and satisfaction only on day 1, which then disappeared, and opioid consumption did not change; no difference or harm was seen at 1-year follow-up either. After eye laser surgery (PRK), CBD 50 mg × 2 in 35 patients gave pain control similar to codeine-acetaminophen; this study had no placebo. In emergency dental pain, a single small RCT reported a positive result with very high doses (10–20 mg/kg). In 36 patients who had both knees replaced at once, oral CBD 400 or 800 mg (4 doses around surgery) did not significantly reduce the primary outcome, 72-hour opioid consumption, compared with placebo; the reduction at 400 mg was seen only in a post hoc analysis, and side effects increased at 800 mg. In healthy volunteers given experimental pain, CBD alone (50–1600 mg) did not reduce pain intensity; when given with an opioid, it increased the opioid's effect on some acute pain measures but not on the prespecified primary measure. CBD added to THC also did not increase THC's analgesic effect. In a meta-analysis combining 18 experimental pain studies of cannabis, THC and THC-like drugs, pain threshold and pain tolerance rose slightly, but pain intensity did not decrease. None of the eight placebo-controlled studies of postoperative and acute pain with THC-containing products or the THC-like drug nabilone clearly reduced pain or opioid requirements; these include two knee replacement RCTs published in 2026, with 111 and 163 patients. Because most studies were small and THC doses were low, the evidence for THC is also weak. In an open-label trial of 469 trauma patients, the daily opioid amount was similar in both groups (median 17 and 15 mg morphine equivalents; results only in the registry, no statistical comparison reported). The studies that reported a benefit had no placebo: an open-label trial of 68 patients in coronary bypass surgery, an uncontrolled dose-escalation study and two retrospective comparisons. Meta-analyses of postoperative and acute pain found no clinically meaningful benefit; in the only meta-analysis that found a small benefit, the effect came from a single study of an experimental synthetic cannabinoid (intramuscular levonantradol). The São Paulo Society of Anesthesiology (2024) does not recommend cannabinoids for acute pain; the American (ASRA 2023) and Canadian (PAIN 2021) guidelines focus on perioperative management of patients who use cannabis. Postoperative nausea and vomiting: none of the four controlled studies of nabilone, dronabinol and IV THC (the largest with 340 patients, a single low dose of nabilone) showed superiority over placebo or standard antiemetics; the strength of evidence for nausea is weak, and no study of pure CBD has published results. October 2026 search (PubMed, Cochrane, ClinicalTrials.gov, Europe PMC): 29 controlled studies of cannabinoids on this topic (19 in patients with postoperative or acute pain, 4 in postoperative nausea, 6 in experimental pain in healthy volunteers with CBD-containing products) and 6 systematic reviews were found; all are in the table below. Experimental pain studies in healthy volunteers using only THC or THC-like drugs are not listed individually in the table: those up to 2017 are represented by a meta-analysis, and later ones were not added separately; three postoperative pain studies with selective or experimental synthetic cannabinoids fell outside the site's scope. There is no Cochrane review; a Cochrane protocol for postoperative nausea was published in 2022, but the review itself could not be found in October 2026.

Evidence assessment: Weak; mostly no benefit

CBD alone

In most RCTs, pure CBD was no different from placebo for postoperative and acute pain and did not reduce opioid use. In a 36-patient pilot RCT in bilateral knee replacement, the primary outcome (72-hour opioid consumption) was also no different from placebo; the reduction at 400 mg appeared only in a post hoc analysis. No study of pure CBD for postoperative nausea has published results.

Products containing THC

In a meta-analysis of cannabinoids after surgery (most containing THC), there was no difference in opioid consumption or pain at 24 hours; at 12 hours there was an increase in pain and a hypotension signal (OR 3.24). In two knee replacement RCTs published in 2026 (111 and 163 patients), dronabinol did not reduce opioid consumption or pain; in a 469-person open-label trial in trauma patients, the daily opioid amount was similar in both groups (results only in the registry, with no statistical comparison). Positive results came only from small studies without placebo or from retrospective studies. For preventing nausea and vomiting, nabilone, dronabinol and IV THC were no better than placebo or standard anti-nausea medicines in four controlled studies.

Evidence: Weak, pointing to no effect: no clinically meaningful benefit in eight placebo-controlled studies or in meta-analyses; the studies are small, THC doses were low, and there is no meta-analysis combining the new trials

Dose range in studies

In pure CBD studies, from 20 mg/day to a 400 mg single dose; in bilateral knee replacement, 4 doses of 400 or 800 mg around surgery; after PRK, 100 mg/day; in experimental pain models, 50–1600 mg single dose; in dental pain, 10–20 mg/kg single dose

Starting dose and titration

Not reported in detail in the studies.

These are doses researchers gave under medical supervision; they are not a recommended dose for you. "mg/kg/day" means milligrams per kilogram of body weight per day.

Pain After Surgery and CBD: studies reviewed
Study	Participants	Product	Dose and titration	Duration	Result	Source
Alaia 2022 Multicenter, double-blind, placebo-controlled RCT	99 (100 randomized) Arthroscopic rotator cuff repair	CBD, buccal tablet (absorbed through the cheek); THC not reported	<80 kg: 25 mg 3 times a day; >80 kg: 50 mg 3 times a day (75–150 mg/day) None (fixed dose by body weight)	14 days	Lower VAS on day 1 (4.4 vs 5.7); no difference on days 2, 7 and 14; higher satisfaction on days 1 and 2; no difference in opioid consumption. At 1-year follow-up (83 patients), no difference in pain, shoulder function or satisfaction (Alaia 2024) Side effects: No difference in liver tests; nausea was monitored	PMID 35905305, doi:10.1177/03635465221109573, NCT04672252, PMID 38322981, doi:10.1177/23259671231222265
Bebee 2021 (CANBACK) Double-blind, placebo-controlled RCT	100 Acute low back pain in the emergency department	Synthetic CBD (>99.9%), 400 mg in 4 mL of MCT oil, single oral dose; no THC	400 mg single dose	Single dose (measured at hour 2)	No difference in pain score at hour 2 (6.2 vs 5.8); similar oxycodone use Side effects: Similar between groups	PMID 33846971, doi:10.5694/mja2.51014, ANZCTR ACTRN12618000487213 (prospectively registered)
Narang 2023 Double-blind, placebo-controlled RCT	90 Ureteroscopy + stent for stones	Epidiolex (oral solution, pure CBD)	20 mg/day	3 days	No difference in pain, opioid use or stent symptoms ("safe but ineffective"); the registry's primary outcome, peak pain on day 3: 3.6 vs 3.2 (p = 0.5) Side effects: No serious side effects; in the registry, other side effects 24/45 vs 21/45	PMID 36891837, doi:10.1097/JU.0000000000003139, NCT04387617
de Andrade Silva 2024 Double-blind, placebo-controlled RCT	Not reported (in the abstract) Root canal treatment patients	CBD-rich cannabis extract, oral, before the procedure; THC ratio not reported	Not reported (in the abstract)	Single session; 7-day follow-up	No difference in postoperative pain or anxiety Side effects: Not reported (in the abstract)	PMID 39505200, doi:10.1016/j.joen.2024.10.010
Chrepa 2024 Phase IIa, placebo-controlled RCT, 3 arms; participants and assessors blinded	61 analyzed (64 enrolled) Emergency dental pain (moderate to severe)	Epidiolex (oral solution, pure CBD, 100 mg/mL)	10 mg/kg or 20 mg/kg single dose	Single dose; 3-hour follow-up, side effect check on day 7	Significant difference from placebo at 10 mg/kg only at minute 180, and at 20 mg/kg at minutes 120 and 180; NNT 3.1 (10 mg/kg) and 2.4 (20 mg/kg) Side effects: Sedation in the first 3 hours 28.5% (10 mg/kg) and 15% (20 mg/kg), 0% with placebo; diarrhea and abdominal pain 20% at 20 mg/kg, 0% with placebo	PMID 37910667, doi:10.1177/00220345231200814, J Dent Res 2024, 103(3):235–242 (online November 2023), PMID 38900211, NCT04642404
Zhou 2026 Randomized, crossover; patients as their own controls (a different drug for each eye); no placebo	35 Adults having PRK (laser correction of vision problems) in both eyes, one after the other	Oral low-THC CBD; comparator codeine-acetaminophen	50 mg twice a day (comparator: codeine-acetaminophen 30/300 mg every 4 hours)	Postoperative recovery period (3-month follow-up)	Average and peak pain no different from codeine-acetaminophen (p=0.538); similar visual recovery; no placebo group Side effects: Few; more perceptual changes in those taking CBD for the first eye	PMID 42524865, doi:10.1097/j.jcrs.0000000000002030, NCT05477875
Haffar 2022 Double-blind, placebo-controlled RCT, 4 arms	80 (19 CBD, 21 essential oil, 21 CBD + essential oil, 19 placebo) Primary total knee replacement	Topical CBD (± essential oil), around the knee; concentration not reported	Not reported (in the abstract); 3 times a day	2 weeks	No difference between CBD and placebo in pain, sleep or 42-day opioid use; the only significant difference was against CBD: on day 2 after surgery, pain was higher in the CBD group than in the essential oil group (VAS 69.9 vs 51.0; p = 0.013) Side effects: Not reported (in the abstract)	PMID 35390457, doi:10.1016/j.arth.2022.03.081
Schneider 2022 (CANAB I) Crossover, double-blind, placebo-controlled RCT	20 Healthy volunteers, electrical experimental pain	Oral CBD	800 mg single dose	Single dose	No difference in pain, hyperalgesia or allodynia; low blood levels (median 5.0 µg/L at minute 130) Side effects: Well tolerated	PMID 34086631, doi:10.1097/j.pain.0000000000002310, NCT03985995
Dieterle 2022 (CANAB II) Crossover, double-blind, placebo-controlled RCT	24 Healthy volunteers, remifentanil-induced hyperalgesia	Oral CBD	1600 mg single dose	Single dose	No effect on opioid-induced hyperalgesia, allodynia or pain Side effects: Well tolerated	PMID 35239547, doi:10.1097/j.pain.0000000000002591, NCT04059978
Arout 2022 Within-subject, double-blind, placebo-controlled	17 Healthy, non-cannabis users	Oral CBD	200 / 400 / 800 mg single dose Fixed-dose arms	Single dose	No consistent analgesia; pain perception was higher than with placebo at all doses Side effects: Small drop in blood pressure; well tolerated	PMID 34223660, doi:10.1111/bcp.14973
Abdallah 2020 Systematic review and meta-analysis (8 RCTs + 4 observational)	924 patients (8 RCTs) + 4,259 patients (4 observational studies) Postoperative pain	Cannabinoids (most containing THC)			No difference in opioid consumption or pain at 24 hours; pain at 12 hours +0.83 cm (95% CI 0.04–1.63); 24-hour results could not be pooled, qualitative synthesis Side effects: Hypotension OR 3.24 (95% CI 1.12–9.36)	PMID 32471924, doi:10.1136/rapm-2020-101340
González Cárdenas 2025 Systematic review and meta-analysis (5 studies)	Acute postoperative pain	Cannabinoids			Meta-analysis could not be done because of heterogeneity; the evidence is conflicting	PMID 39878042, doi:10.1002/ejp.4790
Sideris 2026 Randomized, triple-blind, placebo-controlled, 3-arm parallel pilot RCT	36 randomized (12 per arm; 37 enrolled in the registry) Adults having both knees replaced at once (bilateral total knee replacement) (US)	Epidiolex (oral solution, pure CBD; off-label use); comparator sugar-free syrup	400 mg or 800 mg, 4 doses around surgery	4 doses around surgery; primary outcome at 72 hours	No significant difference from placebo in the primary outcome, 72-hour opioid consumption: 144 vs 209 MME at 400 mg (p = 0.10), 203 vs 209 MME at 800 mg (p = 0.98; Dunnett test). The difference between 400 mg and placebo was significant only in a post hoc analysis (p = 0.04); the abstract states that pain scores and rescue medicine were lower and NSAID use higher in the 400 mg group (no test of these differences in the abstract). Sleep domains improved in the CBD groups; anxiety and depression scores (especially at 800 mg) and IL-6 were higher. A pilot study not powered for efficacy; the authors' interpretation of a "possible signal of benefit" for 400 mg is not based on the primary analysis Side effects: Greater side effect burden at 800 mg (abstract). In the registry, serious side effects placebo 1/12, 400 mg 0/12, 800 mg 1/12; other side effects in 4, 3 and 5 people	PMID 42913966, doi:10.1016/j.jpain.2026.106477, NCT04749628, May 26, 2026)
Abidi 2025 (SWAP) Randomized, 4-arm pilot study (two CBD concentrations, placebo, standard painkiller); CBD and placebo blinded, standard treatment arm open	8 randomized (2 per arm; the registry says 68) Adults having a simple tooth extraction (US)	Oral CBD oil (commercial product with a certificate of analysis; THC content not reported in the article); comparators almond-peppermint oil and ibuprofen + acetaminophen	0.5 mL (17 or 37 mg/mL; about 8.5 or 18.5 mg per dose), every 4–6 hours as needed	7 days; pain followed for 72 hours	Because the numbers were very small, results are descriptive only, with no statistical comparison: pain was lowest in the 37 mg/mL group and similar to the standard ibuprofen-acetaminophen group; the 17 mg/mL group overlapped with placebo. The 17 mg/mL group had much lower pain before surgery (4 vs 10), which distorts the comparison. Stopped at 8 people because of the pandemic Side effects: No serious side effects; mild drowsiness and dry mouth were rare	PMID 41471281, doi:10.3390/ph18121792, NCT04271917, before the study started, the registry lists 68 participants as 'actual', with no results posted, the May 2, 2022 date in the article is the record's last update)
De Vita 2022 Randomized, crossover, 2 × 2 balanced placebo design (the substance given and what participants were told were varied separately)	15 Healthy young adults (ages 18–30), experimental heat and pressure pain (US)	Pure CBD derived from hemp (isolate), oil under the tongue	50 mg single dose	Single dose, 4 sessions	No effect on pain threshold, pain tolerance or pain intensity. How much the pain bothered people decreased compared with the control session both when CBD was given and when no CBD was given but people were told "you received CBD"; being told "you received CBD" by itself changed some measures of pain modulation (an expectation effect) Side effects: No cannabis-related side effects were detected	PMID 34251840, doi:10.1037/pha0000465
Bergeria 2025 Within-subject, double-blind, double-dummy, placebo-controlled randomized laboratory study	31 Healthy volunteers, laboratory pain models (cold water, heat, pressure, capsaicin)	Epidiolex (oral pure CBD) together with 4 mg hydromorphone (an opioid)	50, 100 or 200 mg CBD, single dose with 4 mg hydromorphone Fixed-dose conditions	Single-dose sessions (5 sessions)	No effect on the prespecified primary pain measure (cold water tolerance time); on 3 of 10 acute pain measures, at least one CBD dose increased the opioid's analgesic effect (e.g., peak heat pain decreased with 50 mg); no effect in chronic pain models. CBD increased the opioid's subjective "drug effect" and reduced psychomotor impairment. NIDA-funded; 2 of 8 authors have ties to cannabis companies (research support or consulting: Canopy Growth, Charlotte's Web) Side effects: Side effects and "bad effects" more common with 100 and 200 mg CBD + hydromorphone (drowsiness, nausea, dizziness); no serious side effects	PMID 40839659, doi:10.1097/j.pain.0000000000003561, NCT04036968
Gorbenko 2024 Randomized, double-blind, placebo-controlled, 5-way crossover RCT	37 Healthy volunteers, experimental pain test battery	Oral THC alone or together with CBD; double placebo	THC 9 mg + CBD 0, 10, 30 or 450 mg, single dose Fixed-dose conditions	Single dose, 5 sessions	CBD did not increase THC's analgesic effect at any dose. Instead of reducing them, 450 mg of CBD increased THC's intoxicating effects (feeling "high" increased by 60.5%; 95% CI 12.7–128.5) and its psychomotor, cognitive and autonomic effects; it raised THC blood levels 2.2-fold and its active metabolite 11-OH-THC 6.2-fold (with 10 and 30 mg CBD, effects did not differ from THC alone). Supported by the Dutch government research fund (ZonMw); the affiliation of 1 of 7 authors lists two companies (Verdient Science, Tomori Pharmacology); no conflict-of-interest statement in the PubMed record Side effects: With 450 mg CBD + THC, subjective, psychomotor and autonomic effects increased compared with THC	PMID 39054656, doi:10.1002/cpt.3381
NCT03825965 (Busse pilot, registry results) Multicenter, quadruple-blind, placebo-controlled pilot RCT; primary outcomes were feasibility; results only in the registry (no peer-reviewed publication)	37 randomized (19 drug, 18 placebo); 30 people at month 6 Adults scheduled for total knee replacement (Canada)	Oral CBD-dominant cannabis oil MPL-001 (CBD:THC 25:1; 50 mg CBD, 2 mg THC per mL); comparator MCT oil	Up to 125 mg CBD + 5 mg THC a day (2.5 mL) Increased from 25 mg to 125 mg CBD a day over 2 weeks, then fixed	Starting 4 weeks before surgery until 6 weeks after; 6-month follow-up	Primary outcomes were feasibility: 2.9 patients enrolled per month; those taking at least 75% of the drug before surgery 13/17 vs 11/17, after surgery 10/16 vs 6/17; completing month-6 follow-up 14/19 vs 16/18. Efficacy measures were descriptive only: persistent pain at month 6 2/14 vs 3/16; pain intensity at month 6 3.5 vs 2.6 (0–10); median time to stopping opioids 32 vs 16 days; return to function at week 2 51.7% vs 61.9% (numbers are drug and placebo, respectively). The registry has no statistical comparison. Per protocol, the drug was not used during the 1–2 days in hospital. Supported by the Canadian Institutes of Health Research and university funds Side effects: Nausea or stomach upset 7/19 vs 2/18; 1 serious side effect in the drug group (bowel inflammation)	NCT03825965, September 8, 2026), protocol: Busse 2026, PMID 42032682, doi:10.21203/rs.3.rs-9622221/v1
Thor 2026 Double-blind, placebo-controlled RCT (research letter)	114 randomized; 111 analyzed (55 dronabinol, 56 placebo) Unilateral total knee replacement under regional anesthesia; ages 18–70 with no cannabis or long-term opioid use in the past 3 months (US)	Dronabinol (synthetic THC) capsule; placebo sesame oil capsule	5 mg twice a day, 5 doses in total	5 doses from the morning of surgery to the morning of day 2; 6-month telephone follow-up	No difference in the primary outcome, opioid consumption at 24–48 hours: mean 17.2 vs 23.9 MME (estimated difference −33%; −73 to +8). No difference in pain, reaching discharge criteria, oxygen desaturation, sleep or other secondary outcomes; blinding was successful. Internal institutional funding; one author receives royalties from a prosthesis company Side effects: No serious or other side effects recorded (0 in both groups in the registry); confusion, dizziness, nausea and vomiting scores did not differ	PMID 41838938, doi:10.1097/ALN.0000000000005945, NCT04734080, March 27, 2026)
Jennings 2026 Randomized, triple-blind, placebo-controlled RCT	163 (81 dronabinol, 82 placebo) Patients not using cannabis (confirmed by preoperative urine test) having unilateral total knee replacement (US)	Dronabinol (synthetic THC) pill; placebo pill	2.5 mg twice a day	Postoperative; 6-week follow-up (drug duration not in the abstract; 4 weeks in the likely registry record)	No difference in the primary outcome, total 2-week opioid consumption: 383.6 ± 309.8 vs 367.6 ± 246.3 MME (p = 0.717); in hospital 40.1 vs 38.8 MME (p = 0.901). No difference in pain, sleep duration or nausea and vomiting at weeks 2 and 4, or in patient-reported outcomes at week 6. Funding source not in the abstract Side effects: No complications attributed to the drug or placebo	PMID 41967982, doi:10.1016/j.arth.2026.02.047, NCT04298528, unilateral knee replacement, preoperative cannabis screening, same dose, the registry plans 460 people, drug for 4 weeks, primary outcome 30-day opioid use, status 'unknown', no registry number in the abstract, match could not be confirmed)
NCT05820685 (DOPE, registry results) Pragmatic, open-label (no blinding) RCT; terminated early because the drug became unavailable; results only in the registry (no peer-reviewed publication)	484 randomized (241 standard care, 243 standard care + dronabinol); 469 analyzed Adults hospitalized for acute trauma (US, Houston)	Dronabinol (synthetic THC), added to standard multimodal pain treatment (acetaminophen, naproxen, gabapentin, and oxycodone or tramadol if needed)	10 mg twice a day (the physician could change it if needed)	Throughout the hospital stay (about 11 days)	Primary outcome, daily opioid amount: median 17 (IQR 10–26) MME/day with dronabinol, 15 (9–25) with standard care; total in-hospital opioids median 99 MME in both; opioid prescription at discharge 144/234 vs 133/235. The registry has no statistical comparison and no pain score data; no blinding Side effects: Serious events 13/234 vs 10/235 (unplanned ICU admission 13 vs 8, unplanned intubation 4 vs 3); among those placed on a ventilator, median ventilator time 6 vs 3 days	NCT05820685, June 11, 2025, no publication found in PubMed in October 2026)
Kumar 2024 Randomized, open-label (no placebo or blinding), single-center study; no registry number; ethics approval was obtained for retrospective analysis of anonymized patient data	74 randomized; 68 analyzed (31 dronabinol, 37 control) Adults having first-time coronary bypass surgery (US); long-term opioid or cannabis users were excluded	Dronabinol (synthetic THC), added to standard opioid-based pain treatment	30 mg, 3 doses (before surgery, before removal of the breathing tube and on day 1; 90 mg in total)	Day of surgery and day 1 (3 doses)	Total postoperative opioids were lower in the dronabinol group: 23.7 vs 39.6 MME (p = 0.0037; 40%). No difference in ventilator time, ICU stay or inotrope requirement. Pain scores not reported; because there was no placebo or blinding, opioid decisions may have been influenced; after randomization, 6 patients (long-term opioid or cannabis use) were excluded, and at the analysis stage those receiving circulatory support were also excluded Side effects: No side effects attributed to dronabinol were reported	PMID 38765405, doi:10.7759/cureus.58566
Seeling 2006 Randomized, double-blind, placebo-controlled RCT (article in German)	100 analyzed (number randomized not in the abstract) Men having radical prostate surgery (retropubic prostatectomy and lymph node removal)	Oral dronabinol (synthetic THC)	5 mg, 8 doses	8 doses from the evening before surgery to the morning of day 2; 48-hour follow-up	48-hour patient-controlled opioid (piritramide) consumption did not differ: median 54 mg (IQR 46–88) with dronabinol, 74 mg (44–90) with placebo; the difference was not significant. No synergy or additive effect with the opioid was seen; THC blood levels were measurable in the entire drug group Side effects: Not reported (in the abstract)	PMID 16389542, doi:10.1007/s00101-005-0963-6
Buggy 2003 Randomized, double-blind, placebo-controlled, single-dose RCT	40 (20 + 20) Women who had uterine surgery (abdominal hysterectomy) and requested pain medicine on day 2 after patient-controlled analgesia was stopped (Ireland)	Oral THC capsule	5 mg single dose	Single dose; 6-hour follow-up	No difference in the primary outcome, summed pain intensity difference over 6 hours (SPID): on movement, placebo 7.9, THC 4.3 cm·h (95% CI of the difference −1.8 to 9.0); at rest, 8.8 vs 4.9; time to rescue medicine 217 vs 163 min (no difference) Side effects: Heightened awareness of the surroundings more common with THC (40% vs 5%; p = 0.04); no difference in other side effects	PMID 14581124, doi:10.1016/s0304-3959(03)00331-2
Beaulieu 2006 Randomized, double-blind, placebo-controlled, 4-arm parallel pilot RCT	41 (nabilone 1 mg: 11, 2 mg: 9, ketoprofen: 11, placebo: 10) Adults receiving morphine patient-controlled analgesia after major surgery (gynecologic 46%, orthopedic 44%) (Canada)	Oral nabilone (THC-like synthetic cannabinoid); comparators ketoprofen 50 mg and placebo	1 mg or 2 mg, every 8 hours	24 hours (every 8 hours, 3 doses)	24-hour morphine consumption did not differ among the four groups; in the 2 mg nabilone group, pain scores at rest and on movement were significantly higher than in the other groups. No difference in nausea and vomiting, sleep quality or sedation. Supported by the Canadian Institutes of Health Research and a drug company (Valeant Pharmaceuticals; the product information for nabilone in Canada belongs to this company); single-author pilot study, arms of 9–11 people Side effects: No difference in the number and severity of side effects, euphoria or itching; no serious side effects	PMID 16873343, doi:10.1007/BF03022793
Holdcroft 2006 Multicenter, uncontrolled dose-escalation study (no placebo)	65 (5 mg: 11, 10 mg: 30, 15 mg: 24) Patients aged 18–75 with at least moderate pain after postoperative patient-controlled analgesia was stopped	Oral cannabis plant extract (Cannador; contains THC and CBD)	5, 10 or 15 mg single dose (units as given in the abstract) Dose escalation between groups	Single dose; 6-hour follow-up	The number of people requesting rescue pain medicine fell as the dose rose: 11/11 at 5 mg, 15/30 at 10 mg, 6/24 at 15 mg (trend p < 0.001); pain at rest also decreased (p = 0.01). Because there was no placebo, the size of the effect cannot be known (NNTs were calculated relative to 5 mg). The study was stopped at 15 mg because of a serious fainting (vasovagal) event Side effects: Drowsiness (p = 0.03) and side effects (p = 0.002) increased with dose; serious vasovagal event at 15 mg	PMID 16645457, doi:10.1097/00000542-200605000-00021
Raft 1977 Placebo- and diazepam-controlled clinical study (randomization and blinding not stated in the abstract)	10 Healthy volunteers having a tooth extraction	IV THC; comparators diazepam and lactated Ringer's	0.022 or 0.044 mg/kg (diazepam 0.157 mg/kg)	Single dose (before tooth extraction)	The analgesic effect measured by pain tolerance was smaller with THC than with diazepam and placebo; at the high dose, pain threshold changed unpredictably. Low-dose THC was better than placebo in only 3 people; 6 people preferred placebo as a painkiller, and in these people surgical pain increased Side effects: Not reported (in the abstract)	PMID 832447, doi:10.1002/cpt197721126, PMID 1062533, published in the same period with the same design: anxiety, dysphoria, paranoid thinking and tachycardia with IV THC premedication, no superiority of THC over diazepam or placebo (whether it is the same study could not be confirmed)
Colwill 2020 Randomized, double-blind, placebo-controlled RCT (phase 4)	70 randomized (35 + 35); primary outcome in 66 people Women having a medication abortion (mifepristone + misoprostol, up to 70 days) (US)	Dronabinol (synthetic THC) capsule; everyone also took ibuprofen 800 mg	5 mg single dose, 30 min before misoprostol	Single dose; 24-hour follow-up	No difference in the primary outcome, maximum pain over 24 hours: median 7 vs 7 (p = 0.82); no difference at any time point in pain, maximum anxiety (3.33 vs 3.23) or nausea (2.21 vs 2.72; p = 0.41); satisfaction 76% vs 82% Side effects: In the registry, other side effects 2/35 vs 0/35; no serious side effects	PMID 32459420, doi:10.1097/AOG.0000000000003850, NCT03604341
Levin 2017 Pragmatic, single-center, randomized, placebo-controlled RCT (quadruple-blind in the registry)	340 (172 nabilone, 168 placebo) Adults having planned surgery under general anesthesia with a risk of nausea and vomiting above 60% (Canada)	Oral nabilone (THC-like synthetic cannabinoid); added to other anti-nausea medicines	0.5 mg single dose, before surgery	Single dose; from the recovery room until discharge	Nausea outcome (primary): no difference in the frequency of postoperative nausea and vomiting, 20.9% vs 21.4% (relative risk 0.98; 95% CI 0.89–1.11; p = 0.99). No difference in pain scores, opioid consumption or speed of recovery either Side effects: No difference in reported side effects	PMID 28160217, doi:10.1007/s12630-017-0814-3, NCT02115529
Kleine-Brueggeney 2015 Randomized, double-blind, placebo-controlled RCT; stopped after 40 patients because of lack of efficacy and unacceptable side effects	40 Surgical patients at high risk of nausea and vomiting (Switzerland)	IV THC	0.125 mg/kg, at the end of surgery before waking	Single dose; 24-hour follow-up	Nausea outcome (primary, 24 hours): relative risk reduction 12% (95% CI −37 to 43), not significant; OR adjusted for anesthesia duration 0.97 (0.21–4.43; p = 0.97). The authors concluded that it cannot be recommended for prevention in high-risk patients Side effects: Clinically important psychotropic side effects, especially drowsiness and confusion; the effect of anesthesia did not mask them	PMID 26426861, doi:10.1213/ANE.0000000000000877, NCT00695487, the registry's study director is an author of the article, same dose and timing, in the registry it was stopped on the grounds that 'no effect was seen at interim analysis', and the participant count shows as 320, versus 40 in the article, no registry number in the abstract)
Lewis 1994 Randomized, double-blind, active-controlled RCT (no placebo)	60 randomized; 53 analyzed Women under age 70 having abdominal hysterectomy	Oral nabilone (THC-like synthetic cannabinoid); comparator metoclopramide 10 mg	2 mg single dose, 90 min before anesthesia	Single dose; postoperative period	Nausea outcome: the frequency of nausea (73% vs 70%) and vomiting (54% vs 67%) did not differ between nabilone and metoclopramide; because there was no placebo, the effect of either drug on its own cannot be known Side effects: Not reported (in the abstract)	PMID 7917745, doi:10.1093/bja/73.2.244
NCT00757822 (US Veterans Affairs, registry results) Randomized, triple-blind, active-controlled study (no placebo); results only in the registry (no peer-reviewed publication)	216 enrolled; 180 randomized (92 dronabinol, 88 ondansetron); 121 analyzed (64 + 57) Veterans at high risk of nausea and vomiting having same-day abdominal surgery lasting at least 1 hour (US)	Oral dronabinol (synthetic THC); comparator ondansetron 4 mg IV	5 mg single dose, 20–60 min before surgery	Single dose; 48-hour and 6-week follow-up	Nausea outcome (primary measures): nausea in the recovery room 34.4% vs 29.8% (difference 4.6 points; 95% CI −9.5 to 18.6; p > 0.76), vomiting 12.5% vs 7%; nausea at 24–48 hours 23.4% vs 22.8%. Dronabinol was not better than ondansetron; rescue anti-nausea medicine in the recovery room 25% vs 17%. One third of those randomized were excluded from the analysis Side effects: Serious events (mostly overnight hospital stays) 13/92 vs 10/88	NCT00757822, May 13, 2016, no publication found in PubMed in October 2026)
Gazendam 2020 Systematic review and meta-analysis (6 RCTs, 678 patients)	678 Acute pain (mostly postoperative; including tooth extraction)	Cannabinoids: nabilone (2 studies), oral THC (1; the review classified it as "cannabis oil extract"), intramuscular levonantradol and two experimental synthetic drugs (AZD1940, GW842166)			Small difference in pain across all comparisons (−0.90 points; 95% CI −1.69 to −0.10; heterogeneity 65%); the difference came only from a single study of the experimental synthetic levonantradol given intramuscularly (−2.98). No difference with oral cannabinoids (−0.21; −0.64 to 0.22). GRADE: low certainty Side effects: Serious side effects 3.7% vs 2.6%	PMID 33381643, doi:10.1089/can.2019.0079
Stevens 2017 Systematic review (7 RCTs, 611 patients; qualitative synthesis)	611 Acute pain	Cannabinoid medicines (details not in the abstract)			Analgesic effect equal to placebo in 5 studies, better than placebo in 1 and worse than placebo in 1; no synergy or additive effect with opioids. The authors' conclusion: cannabinoids have no role in treating acute pain Side effects: In 5 of 7 studies, some side effects were more common with cannabinoids	PMID 28090652, doi:10.1111/aas.12851
De Vita 2018 Systematic review and meta-analysis (18 placebo-controlled studies, 442 people)	442 Healthy adults, experimental pain models	Cannabis (6 studies), dronabinol or THC capsules (8), nabilone (2), a cannabis extract containing half as much CBD as THC (1) and two synthetic drugs (HU210, AZD1940); no pure CBD studies			Cannabinoids slightly increased pain threshold (Hedges g = 0.19; 95% CI 0.05–0.32) and pain tolerance (g = 0.23; 0.02–0.44), and reduced the unpleasantness of ongoing pain (g = 0.29; 0.10–0.47); however, they did not reduce pain intensity (g = 0.02; p = 0.81) or mechanical hyperalgesia (g = 0.09; p = 0.23). They may change the emotional response to pain more than they relieve pain	PMID 30422266, doi:10.1001/jamapsychiatry.2018.2503
King 2026 Narrative review with a systematic search (42 observational studies, last 10 years; data not pooled)	42 studies Patients who used cannabis before surgery (compared with non-users)	Cannabis (mostly personal use; product and dose definitions varied)			Of the studies reporting pain, 14 found more postoperative pain in cannabis users, 10 no difference and 2 less; opioid requirements were higher in 18, no different in 17 and lower in 3. Increases were more common in mixed patient groups and spine surgery, and "no difference" more common in joint replacement. Observational data; confounding and differences in how use was defined limit interpretation	PMID 41406677, doi:10.1016/j.jclinane.2025.112097
Shah 2023 (ASRA guideline) Consensus guideline (modified Delphi; 9 questions, 100% agreement in the third round)	Surgical patients who use cannabis or cannabinoids	Cannabis and cannabinoids (including CBD)			All patients should be asked about cannabinoid use before surgery (A); no recommendation for or against routine tapering before surgery (I); frequent users should be told that pain control after surgery may be harder (A) and should be monitored for withdrawal (C); anesthetic doses may be adjusted based on time of last use (C). Focus: safe management of the patient who uses cannabinoids. 1 of 13 authors declared consulting fees from device and drug companies	PMID 36596580, doi:10.1136/rapm-2022-104013
Ladha 2021 (Canadian PAIN consensus) Consensus recommendations (modified Delphi; 17 experts, 4 independent reviewers)	Surgical patients who use cannabis or cannabinoid medicines	Cannabis and cannabinoid medicines			Asking about a history of cannabis use and quantifying it; considering tapering use around surgery; additional prophylaxis against nausea and vomiting; extra attention to depth of anesthesia; being prepared for an increased need for pain medicine after surgery, and watching for withdrawal. Grades of recommendation strength and conflict-of-interest statements are not in the abstract	PMID 33129489, doi:10.1016/j.bja.2020.09.026
de Barros 2024 (São Paulo Society of Anesthesiology) Consensus recommendations (narrative review using the Delphi method; at least 60% agreement, about 90% in the second round)	Use of cannabinoids in pain treatment (acute, cancer, neuropathic, musculoskeletal and other pain)	Cannabinoid products			The task force does not recommend cannabinoids for acute pain; it cites the acute pain meta-analyses (Gazendam 2020, Abdallah 2020) as its basis. It does not recommend them for cancer pain either; for other pain, established treatments should come first. The authors declared no conflicts of interest	PMID 38740135, doi:10.1016/j.bjane.2024.844513
Hickernell 2018 Retrospective matched cohort (not randomized)	243 (81 dronabinol, 162 matched controls) Primary hip or knee replacement performed by a single surgeon (US)	Dronabinol (synthetic THC), added to standard multimodal pain treatment	5 mg twice a day	Hospital stay	No difference in pain score (VAS), walking distance in physical therapy, or nausea and vomiting. In the dronabinol group, hospital stay was shorter (2.3 vs 3.0 days; p = 0.02) and total opioids were lower (252.5 vs 313.3 mg; p = 0.0088); the difference in daily opioids was not significant. Not randomized; confounding cannot be ruled out Side effects: No side effects attributed to dronabinol were reported	PMID 30170713, doi:10.1016/j.arth.2018.07.027
Schneider-Smith 2020 Retrospective matched cohort (pilot)	66 (33 dronabinol, 33 matched controls) Adults hospitalized for trauma (US, level 1 trauma center)	Dronabinol (synthetic THC), added at the physician's discretion, mostly for pain	Mostly 5 or 10 mg twice a day (median 11 mg/day)	48 hours each before and after dronabinol	In patients started on dronabinol, 48-hour opioid consumption fell by 79 MME, while it did not change in controls (−9 MME); difference between pairs p = 0.02; the effect was more pronounced in cannabis users. Observational and small; who was started on dronabinol, and when, may have been selective Side effects: Side effects were not examined; no patient stopped dronabinol	PMID 32154376, doi:10.1136/tsaco-2019-000391, NCT03928015, protocol Swartwood 2020, PMID 32178232
Layeeque 2006 Retrospective before-and-after cohort comparison (not randomized)	242 (127 earlier period, 115 later period) Women having breast surgery under general anesthesia	Oral dronabinol (synthetic THC) and prochlorperazine suppository, given together	Dronabinol 5 mg + prochlorperazine 25 mg, before surgery	Postoperative period	Nausea outcome: with the new protocol, nausea and vomiting rates fell from 59% to 15% and from 29% to 3%, respectively (p < 0.0001); the need for additional anti-nausea medicine decreased. Because the two drugs were given together and different time periods were compared, dronabinol's share of the effect cannot be known Side effects: Not reported (in the abstract)	PMID 16720146, doi:10.1016/j.amjsurg.2005.07.040
Suhre 2020 Retrospective cohort, two academic centers; causal analysis with machine learning and external validation	27,388 (validation set 16,245) ASA 1–3 adults receiving general anesthesia (excluding cardiac and obstetric surgery)	Cannabis (any form; patient's self-report before anesthesia)			Nausea outcome: 10% of patients used cannabis. In daily users, the relative risk of nausea and vomiting in the recovery room was 1.19 (95% CI 1.00–1.45; absolute increase 3.3 points, 0.4–6.4); with non-daily use, 1.07 (0.94–1.21). Observational and based on self-report	PMID 32423445, doi:10.1186/s12871-020-01036-4

Reported side effects

In the dental pain study, sedation, diarrhea and abdominal pain were more common in the CBD groups (Chrepa 2024)
Small drop in blood pressure after a single dose (Arout 2022); hypotension with cannabinoids after surgery OR 3.24 (Abdallah 2020, most containing THC)
With 800 mg CBD (4 doses around surgery), more adverse events and increases in anxiety and depression scores (Sideris 2026, 36 patients)
With IV THC (0.125 mg/kg), clinically important sedation and confusion; the study was stopped early (Kleine-Brueggeney 2015); with nabilone 2 mg, increased postoperative pain scores (Beaulieu 2006); 450 mg CBD increased THC's psychoactive effects and blood levels (Gorbenko 2024)

Monitoring done in studies

Epidiolex label: at 10–20 mg/kg/day, ALT >3× ULN in 13% (placebo 1%); the risk rises markedly with valproate; monitor at baseline, at months 1, 3 and 6, and after dose changes
In healthy adults, at 5 mg/kg/day, ALT/AST >3× ULN in 5.6% (placebo 0%) and eosinophilia (Florian 2025, PMID 40622698); at 1500 mg/day, >5× ULN in 31% (Watkins 2021, PMID 33022751)
Liver enzymes should be monitored when CBD is combined with acetaminophen (paracetamol) and other medicines that burden the liver (Pramhas 2023, PMID 38033459)

Who should be careful

Before surgery: ASRA 2023 recommends asking all patients about cannabinoid use (grade A); product type, route, amount, frequency and time of last use should be recorded; routine toxicology screening is not recommended (grade D)
ASRA makes no recommendation for or against routinely tapering cannabinoids before surgery (grade I). Patients should be told about the possible risks of continuing use around surgery (B). For non-inhaled routes, risks and benefits should be weighed; there are no data supporting a specific waiting period (I). The guideline states that prescription pure CBD (Epidiolex) should not be stopped abruptly around surgery; there are no safety data for non-prescription CBD products
Frequent users should be told that pain control after surgery may be harder (ASRA, A); regular users should be monitored for withdrawal after surgery with a validated scale (C). The risk of withdrawal is considered lower with CBD-dominant products (>10:1 CBD:THC)
Bleeding: no human data have been reported showing that pure CBD increases surgical bleeding; the risk comes through interactions (INR rise with warfarin, reduced clopidogrel effectiveness). In patients taking anticoagulants/antiplatelets, CBD use should be reported to the surgeon and anesthesia team
Risk of hypotension (meta-analysis of cannabinoids after surgery, mostly THC-containing products)
ASRA recommends considering adjusting anesthetic doses based on time of last use and the clinical picture (C); the supporting studies were in cannabis/THC users. That CBD does not change sevoflurane requirements has been shown only in a rat study; no human study of pure CBD has been reported
Postoperative nausea: the risk is slightly higher in daily cannabis users (relative risk 1.19; observational study of 27,000 patients); the Canadian PAIN consensus (2021) recommends additional antiemetic prophylaxis in patients who use cannabis. Cannabinoids themselves (nabilone, dronabinol, IV THC) were not superior to placebo or standard antiemetics for preventing nausea in controlled studies (weak evidence)

Drug interactions

Opioids: no increase in side effects with fentanyl + 400–800 mg CBD; 'bad effects' increased with hydromorphone + 200 mg CBD; pain threshold fell with methadone + 1200 mg CBD. An opioid-sparing effect has not been proven; monitor for sedation
CNS depressants (gabapentin, pregabalin, benzodiazepines, alcohol): additive sedation; somnolence 32% vs 11% with Epidiolex. No direct clinical study of CBD + gabapentinoids has been reported
NSAIDs: on the label, no significant change with the CYP2C9 substrate tolbutamide; no direct study of CBD + NSAIDs has been reported; no documented significant interaction
Acetaminophen (paracetamol): in knee OA, enzyme elevations were more common with acetaminophen 3 g + CBD 600 mg; monitor liver enzymes
Warfarin: in a case report, INR rose and the warfarin dose was reduced; monitor INR when starting or stopping CBD
Clopidogrel: antiplatelet effect may be reduced via CYP2C19 (label); consult cardiology
DOACs (apixaban, rivaroxaban): no direct data reported; uncertain, should be reported and monitored
Valproate (liver, high risk) and clobazam (sedation 46% vs 16%)
Tizanidine, theophylline (CYP1A2): the label recommends considering a dose reduction
Tacrolimus, sirolimus, everolimus, digoxin: monitoring or dose reduction (label)
Strong inducers such as rifampin: CBD levels fall by ~32%
Note: label data come from high-dose prescription CBD; the size of interactions may differ with non-prescription products, but the direction should be assumed to be the same

Abbreviations: RCT, randomized controlled trial (a study in which participants are assigned to groups by chance); placebo, an inactive substance; SMD, OR and RR, effect measures used in analyses that pool studies; CYP, liver enzymes that break down medicines.

If you are considering CBD

If you use CBD or any cannabis product before surgery, tell your surgeon and anesthesia team: the type of product, how much you use and when you last used it all matter.
This conversation is especially important if you take a blood thinner (warfarin, clopidogrel or one of the newer blood thinners).
Use your pain medicines the way your doctor recommends; studies have not shown that CBD reduces the need for opioids.
There is no clear rule on how long before surgery CBD should be stopped; make this decision together with your care team.

Choose your age group, medicines and situation to prepare a short summary you can take to your doctor. Nothing you enter is sent anywhere.

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Bottom line

For postoperative and acute pain, CBD did no better than an inactive substance in most studies and did not reduce the need for opioids. If you use CBD, the most important step is to share this with your surgeon and anesthesia team before surgery.

Frequently asked questions

Does CBD oil work for pain after surgery?

Many studies have looked at this, and in most of them there was no clear difference in pain between people who took CBD and those who took an inactive substance (placebo). After shoulder surgery there was a small difference only on the first day; for dental pain, a single small study reported a positive result. The evidence is weak.

Do I need to say that I use CBD before surgery?

Yes. The 2023 guideline of the American Society of Regional Anesthesia and Pain Medicine (ASRA) recommends that all patients be asked about cannabis product use before surgery. It is important to tell your surgeon and anesthesia team the type of product, how much you use and when you last used it.

Does CBD increase bleeding during surgery?

There are no human data showing that pure CBD directly increases bleeding during surgery. However, it can interact with medicines such as warfarin and clopidogrel. If you take a blood thinner, be sure to tell your surgeon and anesthesia team that you use CBD.

Does CBD reduce the need for opioid painkillers?

In studies, pure CBD did not reduce opioid use after surgery. An analysis that looked mostly at THC-containing cannabis products also found no difference in opioid consumption. In two knee replacement studies published in 2026, dronabinol (synthetic THC) did not reduce opioid use either. The only controlled trial that reported a reduction in opioid use had no placebo and was open-label. The evidence is weak.

Can CBD oil be obtained with a prescription for pain after surgery in Turkey?

In Turkey, products made from cannabis are regulated by the Kenevirden Elde Edilen Ürünlere Dair Yönetmelik (Regulation on Products Derived from Hemp) dated January 31, 2026. These products, including CBD, can be sold only in pharmacies. Those classed as medicines or health products are dispensed with a prescription; the regulation does not state a prescription requirement for supplement products and cosmetics with a THC content of at most 0.3%. As of October 2026, there is no approved (licensed) CBD medicine in Turkey. If you are thinking of using it, talk to your doctor first.

Does CBD prevent nausea after surgery?

No study shows this. There is no study of pure CBD for postoperative nausea with published results. In four controlled studies of THC or THC-like drugs (nabilone, dronabinol, IV THC), nausea and vomiting were no less frequent than with placebo or standard anti-nausea medicines; the evidence is weak. In one observational study, people who used cannabis every day had a slightly higher risk of nausea after surgery; if you use it, telling your anesthesia team allows extra precautions to be taken if needed.

References

Show 43 references

Alaia 2022. Multicenter, double-blind, placebo-controlled RCT. PMID 35905305, doi:10.1177/03635465221109573, NCT04672252, PMID 38322981, doi:10.1177/23259671231222265
Bebee 2021 (CANBACK). Double-blind, placebo-controlled RCT. PMID 33846971, doi:10.5694/mja2.51014, ANZCTR ACTRN12618000487213 (prospectively registered)
Narang 2023. Double-blind, placebo-controlled RCT. PMID 36891837, doi:10.1097/JU.0000000000003139, NCT04387617
de Andrade Silva 2024. Double-blind, placebo-controlled RCT. PMID 39505200, doi:10.1016/j.joen.2024.10.010
Chrepa 2024. Phase IIa, placebo-controlled RCT, 3 arms; participants and assessors blinded. PMID 37910667, doi:10.1177/00220345231200814, J Dent Res 2024, 103(3):235–242 (online November 2023), PMID 38900211, NCT04642404
Zhou 2026. Randomized, crossover; patients as their own controls (a different drug for each eye); no placebo. PMID 42524865, doi:10.1097/j.jcrs.0000000000002030, NCT05477875
Haffar 2022. Double-blind, placebo-controlled RCT, 4 arms. PMID 35390457, doi:10.1016/j.arth.2022.03.081
Schneider 2022 (CANAB I). Crossover, double-blind, placebo-controlled RCT. PMID 34086631, doi:10.1097/j.pain.0000000000002310, NCT03985995
Dieterle 2022 (CANAB II). Crossover, double-blind, placebo-controlled RCT. PMID 35239547, doi:10.1097/j.pain.0000000000002591, NCT04059978
Arout 2022. Within-subject, double-blind, placebo-controlled. PMID 34223660, doi:10.1111/bcp.14973
Abdallah 2020. Systematic review and meta-analysis (8 RCTs + 4 observational). PMID 32471924, doi:10.1136/rapm-2020-101340
González Cárdenas 2025. Systematic review and meta-analysis (5 studies). PMID 39878042, doi:10.1002/ejp.4790
Sideris 2026. Randomized, triple-blind, placebo-controlled, 3-arm parallel pilot RCT. PMID 42913966, doi:10.1016/j.jpain.2026.106477, NCT04749628, May 26, 2026)
Abidi 2025 (SWAP). Randomized, 4-arm pilot study (two CBD concentrations, placebo, standard painkiller); CBD and placebo blinded, standard treatment arm open. PMID 41471281, doi:10.3390/ph18121792, NCT04271917, before the study started, the registry lists 68 participants as 'actual', with no results posted, the May 2, 2022 date in the article is the record's last update)
De Vita 2022. Randomized, crossover, 2 × 2 balanced placebo design (the substance given and what participants were told were varied separately). PMID 34251840, doi:10.1037/pha0000465
Bergeria 2025. Within-subject, double-blind, double-dummy, placebo-controlled randomized laboratory study. PMID 40839659, doi:10.1097/j.pain.0000000000003561, NCT04036968
Gorbenko 2024. Randomized, double-blind, placebo-controlled, 5-way crossover RCT. PMID 39054656, doi:10.1002/cpt.3381
NCT03825965 (Busse pilot, registry results). Multicenter, quadruple-blind, placebo-controlled pilot RCT; primary outcomes were feasibility; results only in the registry (no peer-reviewed publication). NCT03825965, September 8, 2026), protocol: Busse 2026, PMID 42032682, doi:10.21203/rs.3.rs-9622221/v1
Thor 2026. Double-blind, placebo-controlled RCT (research letter). PMID 41838938, doi:10.1097/ALN.0000000000005945, NCT04734080, March 27, 2026)
Jennings 2026. Randomized, triple-blind, placebo-controlled RCT. PMID 41967982, doi:10.1016/j.arth.2026.02.047, NCT04298528, unilateral knee replacement, preoperative cannabis screening, same dose, the registry plans 460 people, drug for 4 weeks, primary outcome 30-day opioid use, status 'unknown', no registry number in the abstract, match could not be confirmed)
NCT05820685 (DOPE, registry results). Pragmatic, open-label (no blinding) RCT; terminated early because the drug became unavailable; results only in the registry (no peer-reviewed publication). NCT05820685, June 11, 2025, no publication found in PubMed in October 2026)
Kumar 2024. Randomized, open-label (no placebo or blinding), single-center study; no registry number; ethics approval was obtained for retrospective analysis of anonymized patient data. PMID 38765405, doi:10.7759/cureus.58566
Seeling 2006. Randomized, double-blind, placebo-controlled RCT (article in German). PMID 16389542, doi:10.1007/s00101-005-0963-6
Buggy 2003. Randomized, double-blind, placebo-controlled, single-dose RCT. PMID 14581124, doi:10.1016/s0304-3959(03)00331-2
Beaulieu 2006. Randomized, double-blind, placebo-controlled, 4-arm parallel pilot RCT. PMID 16873343, doi:10.1007/BF03022793
Holdcroft 2006. Multicenter, uncontrolled dose-escalation study (no placebo). PMID 16645457, doi:10.1097/00000542-200605000-00021
Raft 1977. Placebo- and diazepam-controlled clinical study (randomization and blinding not stated in the abstract). PMID 832447, doi:10.1002/cpt197721126, PMID 1062533, published in the same period with the same design: anxiety, dysphoria, paranoid thinking and tachycardia with IV THC premedication, no superiority of THC over diazepam or placebo (whether it is the same study could not be confirmed)
Colwill 2020. Randomized, double-blind, placebo-controlled RCT (phase 4). PMID 32459420, doi:10.1097/AOG.0000000000003850, NCT03604341
Levin 2017. Pragmatic, single-center, randomized, placebo-controlled RCT (quadruple-blind in the registry). PMID 28160217, doi:10.1007/s12630-017-0814-3, NCT02115529
Kleine-Brueggeney 2015. Randomized, double-blind, placebo-controlled RCT; stopped after 40 patients because of lack of efficacy and unacceptable side effects. PMID 26426861, doi:10.1213/ANE.0000000000000877, NCT00695487, the registry's study director is an author of the article, same dose and timing, in the registry it was stopped on the grounds that 'no effect was seen at interim analysis', and the participant count shows as 320, versus 40 in the article, no registry number in the abstract)
Lewis 1994. Randomized, double-blind, active-controlled RCT (no placebo). PMID 7917745, doi:10.1093/bja/73.2.244
NCT00757822 (US Veterans Affairs, registry results). Randomized, triple-blind, active-controlled study (no placebo); results only in the registry (no peer-reviewed publication). NCT00757822, May 13, 2016, no publication found in PubMed in October 2026)
Gazendam 2020. Systematic review and meta-analysis (6 RCTs, 678 patients). PMID 33381643, doi:10.1089/can.2019.0079
Stevens 2017. Systematic review (7 RCTs, 611 patients; qualitative synthesis). PMID 28090652, doi:10.1111/aas.12851
De Vita 2018. Systematic review and meta-analysis (18 placebo-controlled studies, 442 people). PMID 30422266, doi:10.1001/jamapsychiatry.2018.2503
King 2026. Narrative review with a systematic search (42 observational studies, last 10 years; data not pooled). PMID 41406677, doi:10.1016/j.jclinane.2025.112097
Shah 2023 (ASRA guideline). Consensus guideline (modified Delphi; 9 questions, 100% agreement in the third round). PMID 36596580, doi:10.1136/rapm-2022-104013
Ladha 2021 (Canadian PAIN consensus). Consensus recommendations (modified Delphi; 17 experts, 4 independent reviewers). PMID 33129489, doi:10.1016/j.bja.2020.09.026
de Barros 2024 (São Paulo Society of Anesthesiology). Consensus recommendations (narrative review using the Delphi method; at least 60% agreement, about 90% in the second round). PMID 38740135, doi:10.1016/j.bjane.2024.844513
Hickernell 2018. Retrospective matched cohort (not randomized). PMID 30170713, doi:10.1016/j.arth.2018.07.027
Schneider-Smith 2020. Retrospective matched cohort (pilot). PMID 32154376, doi:10.1136/tsaco-2019-000391, NCT03928015, protocol Swartwood 2020, PMID 32178232
Layeeque 2006. Retrospective before-and-after cohort comparison (not randomized). PMID 16720146, doi:10.1016/j.amjsurg.2005.07.040
Suhre 2020. Retrospective cohort, two academic centers; causal analysis with machine learning and external validation. PMID 32423445, doi:10.1186/s12871-020-01036-4

Points that could not be verified from the full text

The full text of the following studies could not be obtained, and some fields come only from the abstract: de Andrade Silva 2024 (n, dose, side effects, THC ratio), Haffar 2022 (topical concentration, amount, side effects), Alaia 2022 (THC content), Narang 2023 (side effect details); Schneider 2022, Arout 2022 and two meta-analyses are also from the abstract only. Of those added in October 2026, Sideris 2026, Jennings 2026, Buggy 2003, Seeling 2006 (German), Holdcroft 2006, Raft 1977, Colwill 2020, Gorbenko 2024, Levin 2017, Kleine-Brueggeney 2015, Lewis 1994, Stevens 2017, King 2026, Hickernell 2018, Layeeque 2006 and the ASRA 2023 and PAIN 2021 guidelines were also read from the abstract only (together with the ClinicalTrials.gov record where available); the abstract and funding information for Beaulieu 2006 are from the publisher's page
Studies without a peer-reviewed publication: as of October 2026, the results of NCT03825965 (knee replacement, CBD:THC 25:1, pilot, 37 people) and NCT05820685 (trauma, dronabinol, 484 people) are only on ClinicalTrials.gov, and the registry has no statistical comparison; the table shows only their numbers. NCT00757822 (postoperative nausea, dronabinol vs ondansetron, 216 people) was not published in a peer-reviewed journal either, but its registry record includes comparison tests. A non-peer-reviewed preprint of NCT03825965 appeared in June 2026. The results of NCT04749628 (bilateral knee replacement, CBD 400/800 mg) were published in a peer-reviewed journal in October 2026 (Sideris 2026); NCT05240755 (shoulder arthroscopy, open-label) was completed in August 2024, with no results
Registered studies with no results found or still ongoing (October 2026): pure CBD for postoperative nausea (NCT06137027, Jamaica, 120 people planned), preoperative THC + CBD premedication (NCT02283281, Israel, 200 people planned), nabilone after inflammatory bowel disease surgery (NCT03422861), THC + CBD oil for acute pain due to a herniated lumbar disc (NCT04816994), dronabinol in spinal fusion (NCT04346407), CBD in knee replacement (NCT03675971; NCT06234631, 380 people, ongoing), CBD in shoulder surgery (NCT06381791), CBD for long bone fractures (NCT06448923, 225 people), dronabinol in arthroscopy (NCT05335252), THC in major abdominal surgery (NCT01790555, Netherlands, 40 people planned), and the effect of a CBD + THC tablet on pain and stress responses in healthy volunteers (NCT04226690, 24 people, ended in December 2023). A Cochrane review protocol on cannabis-based medicines for postoperative nausea was published in 2022 (CD014567); the review itself could not be found
The registry record of the tooth extraction pilot study (Abidi 2025) lists 68 participants as 'actual', while the article reports that 8 people were randomized; May 2, 2022, given in the article as the registration date, is according to ClinicalTrials.gov the record's last update date (registration was in February 2020, before the study started). Kleine-Brueggeney 2015 and NCT00695487 (same hospital, same dose and timing, same reason for stopping; the registry shows 320 participants, the article 40) and Jennings 2026 and NCT04298528 (same center, investigator and dose; the registry plans 460 people, with the drug for 4 weeks and a primary outcome of 30-day opioid use, while the article reports 2-week opioid use) are very likely the same studies; this could not be confirmed because the full texts could not be read. Haffar 2022 and NCT04585230 are also from the same center with the same four-arm design, but the registry lists 92 people and 'mineral oil' (the article: 80 people and 'essential oil'); the match could not be confirmed

Research history

Here we record what changed on this page, when and why, with dates. The newest change is at the top.

October 28, 2026
The October 2026 search added 31 studies, and on October 28, 2026 the scope was widened so that postoperative nausea and vomiting joined this page as a separate section. Added: a pilot RCT of pure CBD in bilateral knee replacement (Sideris 2026) and a CBD pilot study in tooth extraction; three experimental pain studies with CBD-containing products; ten controlled studies of THC-containing drugs and nabilone for postoperative and acute pain (including the two knee replacement RCTs published in 2026; the results of two are only on ClinicalTrials.gov) and an uncontrolled dose-escalation study; four controlled studies in postoperative nausea (one only in the registry); two systematic reviews in acute pain and one in experimental pain; a review summarizing postoperative pain in cannabis users; recommendations from the American, Canadian and São Paulo anesthesia societies; four observational studies. Registry numbers, figures and confidence intervals were added to the Bebee, Narang, Chrepa, Haffar, Schneider, Dieterle and Abdallah rows; the single significant difference against CBD in Haffar 2022 was written into its row. The topic text was updated for the new studies, the nausea section and the search counts. The conclusion and the strength of evidence did not change.
Related studies: Sideris 2026, published October 22, 2026 (PMID 42913966, doi:10.1016/j.jpain.2026.106477, NCT04749628, May 26, 2026)); Abidi 2025 (SWAP), published November 25, 2025 (PMID 41471281, doi:10.3390/ph18121792, NCT04271917, before the study started, the registry lists 68 participants as 'actual', with no results posted, the May 2, 2022 date in the article is the record's last update)); De Vita 2022, published October 2022 (PMID 34251840, doi:10.1037/pha0000465); Bergeria 2025, published February 28, 2025 (PMID 40839659, doi:10.1097/j.pain.0000000000003561, NCT04036968); Gorbenko 2024, published November 2024 (PMID 39054656, doi:10.1002/cpt.3381); NCT03825965 (Busse pilot, registry results), published September 8, 2026 (registry results) (NCT03825965, September 8, 2026), protocol: Busse 2026, PMID 42032682, doi:10.21203/rs.3.rs-9622221/v1); Thor 2026, published May 2026 (PMID 41838938, doi:10.1097/ALN.0000000000005945, NCT04734080, March 27, 2026)); Jennings 2026, published July 2026 (PMID 41967982, doi:10.1016/j.arth.2026.02.047, NCT04298528, unilateral knee replacement, preoperative cannabis screening, same dose, the registry plans 460 people, drug for 4 weeks, primary outcome 30-day opioid use, status 'unknown', no registry number in the abstract, match could not be confirmed)); NCT05820685 (DOPE, registry results), published June 11, 2025 (registry results) (NCT05820685, June 11, 2025, no publication found in PubMed in October 2026)); Kumar 2024, published April 2024 (PMID 38765405, doi:10.7759/cureus.58566); Seeling 2006, published April 2006 (PMID 16389542, doi:10.1007/s00101-005-0963-6); Buggy 2003, published November 2003 (PMID 14581124, doi:10.1016/s0304-3959(03)00331-2); Beaulieu 2006, published August 2006 (PMID 16873343, doi:10.1007/BF03022793); Holdcroft 2006, published May 2006 (PMID 16645457, doi:10.1097/00000542-200605000-00021); Raft 1977, published January 1977 (PMID 832447, doi:10.1002/cpt197721126, PMID 1062533, published in the same period with the same design: anxiety, dysphoria, paranoid thinking and tachycardia with IV THC premedication, no superiority of THC over diazepam or placebo (whether it is the same study could not be confirmed)); Colwill 2020, published June 2020 (PMID 32459420, doi:10.1097/AOG.0000000000003850, NCT03604341); Levin 2017, published April 2017 (PMID 28160217, doi:10.1007/s12630-017-0814-3, NCT02115529); Kleine-Brueggeney 2015, published November 2015 (PMID 26426861, doi:10.1213/ANE.0000000000000877, NCT00695487, the registry's study director is an author of the article, same dose and timing, in the registry it was stopped on the grounds that 'no effect was seen at interim analysis', and the participant count shows as 320, versus 40 in the article, no registry number in the abstract)); Lewis 1994, published August 1994 (PMID 7917745, doi:10.1093/bja/73.2.244); NCT00757822 (US Veterans Affairs, registry results), published May 13, 2016 (registry results) (NCT00757822, May 13, 2016, no publication found in PubMed in October 2026)); Gazendam 2020, published December 2020 (PMID 33381643, doi:10.1089/can.2019.0079); Stevens 2017, published March 2017 (PMID 28090652, doi:10.1111/aas.12851); De Vita 2018, published November 2018 (PMID 30422266, doi:10.1001/jamapsychiatry.2018.2503); King 2026, published February 2026 (PMID 41406677, doi:10.1016/j.jclinane.2025.112097); Shah 2023 (ASRA guideline), published March 2023 (PMID 36596580, doi:10.1136/rapm-2022-104013); Ladha 2021 (Canadian PAIN consensus), published January 2021 (PMID 33129489, doi:10.1016/j.bja.2020.09.026); de Barros 2024 (São Paulo Society of Anesthesiology), published July–August 2024 (PMID 38740135, doi:10.1016/j.bjane.2024.844513); Hickernell 2018, published December 2018 (PMID 30170713, doi:10.1016/j.arth.2018.07.027); Schneider-Smith 2020, published February 2020 (PMID 32154376, doi:10.1136/tsaco-2019-000391, NCT03928015, protocol Swartwood 2020, PMID 32178232); Layeeque 2006, published June 2006 (PMID 16720146, doi:10.1016/j.amjsurg.2005.07.040); Suhre 2020, published May 18, 2020 (PMID 32423445, doi:10.1186/s12871-020-01036-4)
October 22, 2026
The names of the finding labels were simplified: the "No benefit seen" label on this page became "No effect found". The assessment did not change.
October 21, 2026
PubMed and ClinicalTrials.gov were searched for newly published and previously missed clinical studies. Study added: Zhou 2026. The 1-year follow-up results of the Alaia 2022 study (Alaia 2024) were added to that study's row. The conclusion and the strength of evidence did not change.
Related studies: Zhou 2026, published July 29, 2026 (PMID 42524865, doi:10.1097/j.jcrs.0000000000002030, NCT05477875); Alaia 2022, published September 2022 (PMID 35905305, doi:10.1177/03635465221109573, NCT04672252, PMID 38322981, doi:10.1177/23259671231222265)

Older changes (2)

October 21, 2026
The full texts of the studies were reread and the information on the page was checked against its sources. Corrected: product, duration, registry number and study design details in the study table; the "Who should be careful" list. Points that could not be confirmed from the full text dropped from 4 items to 2. The year of 2 publications named on the page was corrected to the journal's print year instead of the online publication year. The conclusion and the strength of evidence did not change.
October 19, 2026
Page published. This first review looked at 11 studies.

Evidence changes across all topics