CBD Drug Interaction Checker

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

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

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

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

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

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

Clobazam: If you take clobazam, CBD can raise the medicine's active metabolite about 3-fold and can increase drowsiness. Do not start without talking to your neurologist.

FDA Epidiolex label §7.2, §12.3 (05/2026), EMA prescribing information §4.5, PMID 26114620

Valproate and the liver: Liver enzyme elevations were more common when CBD was used together with valproate. Your doctor should monitor your liver tests.

DailyMed Epidiolex label 5.1, PMID 28782097

Other epilepsy medicines: With epilepsy medicines, CBD can change the blood levels of some of them. Your doctor may monitor your drug levels and side effects.

PMID 28782097, PMID 33541771, PMID 37593907, PMID 31211851, PMID 30791225

Other epilepsy medicines: With epilepsy medicines, CBD can change the blood levels of some of them. Your doctor may monitor your drug levels and side effects.

PMID 28782097, PMID 33541771, PMID 37593907, PMID 31211851, PMID 30791225

Other epilepsy medicines: With epilepsy medicines, CBD can change the blood levels of some of them. Your doctor may monitor your drug levels and side effects.

PMID 28782097, PMID 33541771, PMID 37593907, PMID 31211851, PMID 30791225

Other epilepsy medicines: With epilepsy medicines, CBD can change the blood levels of some of them. Your doctor may monitor your drug levels and side effects.

PMID 28782097, PMID 33541771, PMID 37593907, PMID 31211851, PMID 30791225

Other epilepsy medicines: With epilepsy medicines, CBD can change the blood levels of some of them. Your doctor may monitor your drug levels and side effects.

PMID 28782097, PMID 33541771, PMID 37593907, PMID 31211851, PMID 30791225

Other epilepsy medicines: With epilepsy medicines, CBD can change the blood levels of some of them. Your doctor may monitor your drug levels and side effects.

PMID 28782097, PMID 33541771, PMID 37593907, PMID 31211851, PMID 30791225

Strong enzyme inducers: These medicines can lower the level of CBD in the blood: with rifampin it fell by about one third. There are no direct measurements with others such as carbamazepine; the prescribing information expects a similar drop. Tell your doctor.

DailyMed Epidiolex label 7.1, EMA Epidyolex SmPC 4.5

Lamotrigine: In 63 people with epilepsy taking approved CBD, lamotrigine blood levels did not change as the CBD dose went up; the European package leaflet says no dose adjustment is needed. Still tell your doctor about the medicines you take.

PMID 37593907, EMA Epidyolex SmPC 4.5

Other epilepsy medicines: With epilepsy medicines, CBD can change the blood levels of some of them. Your doctor may monitor your drug levels and side effects.

PMID 28782097, PMID 33541771, PMID 37593907, PMID 31211851, PMID 30791225

SSRIs (fluoxetine, paroxetine): In a young person taking fluoxetine, worsening insomnia, restlessness and obsessive symptoms were reported after CBD oil was added (a single case). The reported case of a child taking paroxetine involved smoked marijuana, not CBD. Tell your doctor or pharmacist.

PMID 35652796, PMID 39719830

SSRIs (fluoxetine, paroxetine): In a young person taking fluoxetine, worsening insomnia, restlessness and obsessive symptoms were reported after CBD oil was added (a single case). The reported case of a child taking paroxetine involved smoked marijuana, not CBD. Tell your doctor or pharmacist.

PMID 35652796, PMID 39719830

Citalopram, escitalopram: CBD raised citalopram blood levels: a significant rise in a series of 6 patients; in healthy volunteers, citalopram exposure (AUC) rose by 43% after 12 days of approved CBD (2.5 mg/kg twice a day). If you take these medicines, talk to your doctor.

PMID 34121064, PMID 41622700

Citalopram, escitalopram: CBD raised citalopram blood levels: a significant rise in a series of 6 patients; in healthy volunteers, citalopram exposure (AUC) rose by 43% after 12 days of approved CBD (2.5 mg/kg twice a day). If you take these medicines, talk to your doctor.

PMID 34121064, PMID 41622700

Sertraline: In a 78-year-old patient who had taken sertraline for 20 years, blood sodium dropped and forgetfulness developed in the months after over-the-counter CBD was added; it resolved after CBD and then sertraline were stopped (a single case; CBD's role was rated "possible"). In two adverse event reports from Poland, people taking CBD oil together with sertraline had diarrhea, vomiting, fever and severe fatigue. Tell your doctor or pharmacist.

PMID 36627907, PMID 39502532, PMID 34121064

Mirtazapine: In the lab, CBD had very little effect on the breakdown of mirtazapine; this has not been measured in patients. Still tell your doctor about the medicines you take.

PMID 34121064

SNRIs and tricyclic antidepressants: There are no clinical data on interactions between CBD and SNRIs or tricyclics other than amitriptyline (see the separate warning for amitriptyline). Still tell your doctor about all the medicines you take.

PMID 38868665

SNRIs and tricyclic antidepressants: There are no clinical data on interactions between CBD and SNRIs or tricyclics other than amitriptyline (see the separate warning for amitriptyline). Still tell your doctor about all the medicines you take.

PMID 38868665

Amitriptyline: In healthy volunteers, a single 30 mg dose of CBD oil raised the blood level (AUC) of amitriptyline by 13% and its peak level by 17%; the effect is said to possibly be larger with ongoing use. Tell your doctor or pharmacist.

PMID 41398552

Bupropion: In a study with approved CBD (7.5 mg/kg twice a day), the blood level of bupropion fell by about 20% and its active breakdown product did not change; the package leaflet does not consider this difference clinically significant. The effect of higher CBD doses is not known. Tell your doctor.

EMA Epidyolex SmPC 4.5, FDA Epidiolex label §12.3 (05/2026)

Alprazolam, trazodone, buspirone: No study has looked at these medicines and CBD together. The data on the enzyme that breaks them all down (CYP3A4) conflict: approved CBD (750 mg twice a day) did not affect this enzyme, while a single dose of a CBD-dominant extract raised the blood level of midazolam, which is broken down the same way, by 56%. Drowsiness and sedation may increase when they are taken together. Tell your doctor.

FDA Epidiolex label §7.4 and §12.3 (05/2026), PMID 37313955, Alprazolam prescribing information §12.3, dailymed.nlm.nih.gov, Trazodone prescribing information §12.3, dailymed.nlm.nih.gov, Buspirone prescribing information (Drug Interactions), dailymed.nlm.nih.gov

Atomoxetine, vortioxetine: No human study has looked at these medicines and CBD together. CBD slowed the main enzyme that breaks down both of them (CYP2D6) in the lab; however, in a study in healthy volunteers, this enzyme's activity did not change. Tell your doctor about the medicines you take.

PMID 21821735, PMID 37313955, Atomoxetine prescribing information §12.3, dailymed.nlm.nih.gov, Vortioxetine prescribing information §12.3, dailymed.nlm.nih.gov

Agomelatine: No study has looked at agomelatine and CBD together. Agomelatine is broken down almost entirely by the CYP1A2 enzyme; approved CBD raised the blood level (AUC) of caffeine, which is broken down the same way, about 2-fold. Both medicines can raise liver enzymes. Tell your doctor about CBD; it matters that they know this when looking at your liver tests.

PMID 33951339, FDA Epidiolex label §5.1, §7.2 (05/2026), EMA Valdoxan SmPC 4.5

Benzodiazepines, sleep medicines and sedatives: Drowsiness and sedation may increase together with CBD. Talk to your doctor before using them together.

Alprazolam, trazodone, buspirone: No study has looked at these medicines and CBD together. The data on the enzyme that breaks them all down (CYP3A4) conflict: approved CBD (750 mg twice a day) did not affect this enzyme, while a single dose of a CBD-dominant extract raised the blood level of midazolam, which is broken down the same way, by 56%. Drowsiness and sedation may increase when they are taken together. Tell your doctor.

DailyMed Epidiolex label 7.4, EMA Epidyolex SmPC 4.4

FDA Epidiolex label §7.4 and §12.3 (05/2026), PMID 37313955, Alprazolam prescribing information §12.3, dailymed.nlm.nih.gov, Trazodone prescribing information §12.3, dailymed.nlm.nih.gov, Buspirone prescribing information (Drug Interactions), dailymed.nlm.nih.gov

Benzodiazepines, sleep medicines and sedatives: Drowsiness and sedation may increase together with CBD. Talk to your doctor before using them together.

Clonazepam: In 45 people with epilepsy taking approved CBD, clonazepam blood levels did not change as the CBD dose went up. Still, drowsiness may increase when they are taken together; tell your doctor.

DailyMed Epidiolex label 7.4, EMA Epidyolex SmPC 4.4

PMID 37593907

Benzodiazepines, sleep medicines and sedatives: Drowsiness and sedation may increase together with CBD. Talk to your doctor before using them together.

Diazepam: No study has measured diazepam blood levels with CBD. One of the enzymes that break down diazepam (CYP2C19) is slowed by CBD: approved CBD raised the blood level of a clobazam breakdown product, which is broken down by this enzyme, about 3-fold. In epilepsy, the safety and effect of diazepam used as a nasal spray during a seizure did not change with CBD. Drowsiness may increase when they are taken together; tell your doctor.

DailyMed Epidiolex label 7.4, EMA Epidyolex SmPC 4.4

FDA Epidiolex label §12.3 (05/2026), PMID 37313955, PMID 37210793, Diazepam prescribing information (Clinical pharmacology), dailymed.nlm.nih.gov

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

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

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

Alprazolam, trazodone, buspirone: No study has looked at these medicines and CBD together. The data on the enzyme that breaks them all down (CYP3A4) conflict: approved CBD (750 mg twice a day) did not affect this enzyme, while a single dose of a CBD-dominant extract raised the blood level of midazolam, which is broken down the same way, by 56%. Drowsiness and sedation may increase when they are taken together. Tell your doctor.

FDA Epidiolex label §7.4 and §12.3 (05/2026), PMID 37313955, Alprazolam prescribing information §12.3, dailymed.nlm.nih.gov, Trazodone prescribing information §12.3, dailymed.nlm.nih.gov, Buspirone prescribing information (Drug Interactions), dailymed.nlm.nih.gov

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

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

Antipsychotics: No published study has measured antipsychotic blood levels with CBD. In schizophrenia studies, CBD (600–1000 mg a day) added for 6 weeks to the antipsychotic being taken was generally well tolerated; in one study, drowsiness was more common in those taking CBD. Drowsiness may increase when they are taken together; tell your doctor.

PMID 29241357, PMID 29619533, FDA Epidiolex label §7.4 (05/2026)

Antipsychotics: No published study has measured antipsychotic blood levels with CBD. In schizophrenia studies, CBD (600–1000 mg a day) added for 6 weeks to the antipsychotic being taken was generally well tolerated; in one study, drowsiness was more common in those taking CBD. Drowsiness may increase when they are taken together; tell your doctor.

PMID 29241357, PMID 29619533, FDA Epidiolex label §7.4 (05/2026)

Antipsychotics: No published study has measured antipsychotic blood levels with CBD. In schizophrenia studies, CBD (600–1000 mg a day) added for 6 weeks to the antipsychotic being taken was generally well tolerated; in one study, drowsiness was more common in those taking CBD. Drowsiness may increase when they are taken together; tell your doctor.

PMID 29241357, PMID 29619533, FDA Epidiolex label §7.4 (05/2026)

Antipsychotics: No published study has measured antipsychotic blood levels with CBD. In schizophrenia studies, CBD (600–1000 mg a day) added for 6 weeks to the antipsychotic being taken was generally well tolerated; in one study, drowsiness was more common in those taking CBD. Drowsiness may increase when they are taken together; tell your doctor.

PMID 29241357, PMID 29619533, FDA Epidiolex label §7.4 (05/2026)

Antipsychotics: No published study has measured antipsychotic blood levels with CBD. In schizophrenia studies, CBD (600–1000 mg a day) added for 6 weeks to the antipsychotic being taken was generally well tolerated; in one study, drowsiness was more common in those taking CBD. Drowsiness may increase when they are taken together; tell your doctor.

Clozapine: No study has looked at clozapine and CBD together. Clozapine is broken down mainly by CYP1A2, and also by CYP2D6 and CYP3A4; approved CBD raised the total amount in the blood of caffeine, which is broken down by CYP1A2, about 2-fold. The clozapine prescribing information recommends close monitoring of the patient, and lowering the clozapine dose if needed, when it is combined with weak or moderate CYP1A2 inhibitors such as caffeine and birth control pills. Do not start without talking to your psychiatrist.

PMID 29241357, PMID 29619533, FDA Epidiolex label §7.4 (05/2026)

PMID 33951339, FDA Epidiolex label §7.2 (05/2026), Clozapine prescribing information §2.7 and §7.1, dailymed.nlm.nih.gov

Antipsychotics: No published study has measured antipsychotic blood levels with CBD. In schizophrenia studies, CBD (600–1000 mg a day) added for 6 weeks to the antipsychotic being taken was generally well tolerated; in one study, drowsiness was more common in those taking CBD. Drowsiness may increase when they are taken together; tell your doctor.

PMID 29241357, PMID 29619533, FDA Epidiolex label §7.4 (05/2026)

Lithium: In a 13-year-old patient who had taken the same dose of lithium for a long time, lithium toxicity developed a few weeks after CBD was started (blood level 2.4 mmol/L; earlier levels 1–1.3); it resolved when lithium was stopped. The patient was also taking other medicines and drinking little fluid; CBD's role was rated "possible", and the cause is not known. Do not start without talking to your psychiatrist.

PMID 32851114, PMID 39719830

Methylphenidate: In healthy volunteers, 3 days of high-dose approved CBD (750 mg twice a day) raised the blood level of methylphenidate by about 9% on average; the researchers found this difference clinically unimportant. How large the effect is with long-term use, or with products containing THC, is not known. If you take an ADHD medicine, tell your doctor about CBD.

PMID 36467779, PMID 35512806

Atomoxetine, vortioxetine: No human study has looked at these medicines and CBD together. CBD slowed the main enzyme that breaks down both of them (CYP2D6) in the lab; however, in a study in healthy volunteers, this enzyme's activity did not change. Tell your doctor about the medicines you take.

PMID 21821735, PMID 37313955, Atomoxetine prescribing information §12.3, dailymed.nlm.nih.gov, Vortioxetine prescribing information §12.3, dailymed.nlm.nih.gov

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)

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)

Tacrolimus: If you take tacrolimus, CBD can markedly raise the medicine's blood level: in a controlled study in healthy volunteers taking approved CBD, the total amount of tacrolimus in the blood rose about 3-fold; a similar rise was reported in a patient taking CBD for epilepsy. The tacrolimus prescribing information recommends close monitoring of blood levels with CBD, and lowering the dose if needed. Do not start without talking to your transplant team.

PMID 39601108, PMID 31012522, PMID 29579828, Tacrolimus prescribing information §5.17 and §7.3, dailymed.nlm.nih.gov

Cyclosporine: If you take cyclosporine, tell your transplant team about CBD. In a small study, cyclosporine levels stayed stable; data are limited.

PMID 29579828

Everolimus, sirolimus: In a controlled study in healthy volunteers taking approved CBD, the blood level of everolimus rose about 2.5-fold; in patients with TSC (tuberous sclerosis complex), everolimus and sirolimus levels rose in most patients when CBD was added. The prescribing information for both medicines recommends close monitoring of blood levels with CBD, and lowering the dose if needed. Do not start without talking to your doctor; your drug level should be monitored.

EMA Epidyolex SmPC 4.5, PMID 37132402, PMID 31924480, Everolimus (Afinitor) prescribing information §2.11 and §7.1, dailymed.nlm.nih.gov, Everolimus (Zortress) prescribing information §5.22 and §7.1, dailymed.nlm.nih.gov, Sirolimus prescribing information §5.21 and §7.5, dailymed.nlm.nih.gov

Everolimus, sirolimus: In a controlled study in healthy volunteers taking approved CBD, the blood level of everolimus rose about 2.5-fold; in patients with TSC (tuberous sclerosis complex), everolimus and sirolimus levels rose in most patients when CBD was added. The prescribing information for both medicines recommends close monitoring of blood levels with CBD, and lowering the dose if needed. Do not start without talking to your doctor; your drug level should be monitored.

EMA Epidyolex SmPC 4.5, PMID 37132402, PMID 31924480, Everolimus (Afinitor) prescribing information §2.11 and §7.1, dailymed.nlm.nih.gov, Everolimus (Zortress) prescribing information §5.22 and §7.1, dailymed.nlm.nih.gov, Sirolimus prescribing information §5.21 and §7.5, dailymed.nlm.nih.gov

Mycophenolate: CBD raised the total amount of mycophenolic acid in the blood by about one third (35%); at a higher CBD dose, the rise is estimated to be 58%. Tell your doctor.

EMA Epidyolex SmPC 4.5

Tamoxifen: In one case, the active breakdown product of tamoxifen (endoxifen) was found to be lower while the person was taking 40 mg of CBD a day. In a small study of 15 patients taking tamoxifen, about 50 mg a day of THC-free CBD oil lowered endoxifen by 12.6% on average; the researchers did not consider this difference important at this dose, and the effect of higher doses is not known. Do not start without talking to your oncologist.

PMID 33191836, PMID 37543688

Chemotherapy and cancer medicines: Data on interactions between CBD and cancer medicines are very limited. Talk to your oncologist before using it.

PMID 30776990, PMID 38478773

Immunotherapy (checkpoint inhibitors): In some observational studies, cannabis users had a lower response to immunotherapy or shorter survival; other studies found no difference, and the results conflict. Cause and effect has not been proven, most studies were done with cannabis containing THC, and there are no data specific to pure CBD. Guidelines advise caution; do not start without talking to your oncologist.

PMID 30670598, PMID 32872248, PMID 35454955, PMID 38610922, PMID 39737331, PMID 36535195, PMID 40184324, PMID 38478773, PMID 36872397

Strong enzyme inducers: These medicines can lower the level of CBD in the blood: with rifampin it fell by about one third. There are no direct measurements with others such as carbamazepine; the prescribing information expects a similar drop. Tell your doctor.

DailyMed Epidiolex label 7.1, EMA Epidyolex SmPC 4.5

Strong enzyme inducers: These medicines can lower the level of CBD in the blood: with rifampin it fell by about one third. There are no direct measurements with others such as carbamazepine; the prescribing information expects a similar drop. Tell your doctor.

DailyMed Epidiolex label 7.1, EMA Epidyolex SmPC 4.5

Digoxin: If you take digoxin, talk to your doctor. The package leaflet says CBD may raise the level of this medicine and recommends monitoring the level; no clinical cases have been reported.

EMA Epidyolex SmPC 4.5

Statins, birth control pills: No published human study was found that looked at these medicines and CBD together. The European patient information for approved CBD lists simvastatin among the medicines to tell the doctor about, because doses may need adjusting. It is still recommended that you tell your doctor about all the medicines you take.

PMID 41633759, EMA Epidyolex patient information section 2, EMA Epidyolex SmPC 5.2, Birth control pill prescribing information §7.1, dailymed.nlm.nih.gov

Blood pressure medicines and low blood pressure: CBD can lower blood pressure by a few mmHg; if you take blood pressure medicine or your blood pressure is low, dizziness and a drop in blood pressure may occur. In a study with a single dose of a CBD-dominant cannabis extract, the blood level of losartan went up, but its conversion to the breakdown product that provides most of its effect went down; the net effect of this on blood pressure is not known. Talk to your doctor.

PMID 37093160, PMID 28614793, PMID 37313955, Losartan prescribing information §12.3, dailymed.nlm.nih.gov

Blood pressure medicines and low blood pressure: CBD can lower blood pressure by a few mmHg; if you take blood pressure medicine or your blood pressure is low, dizziness and a drop in blood pressure may occur. In a study with a single dose of a CBD-dominant cannabis extract, the blood level of losartan went up, but its conversion to the breakdown product that provides most of its effect went down; the net effect of this on blood pressure is not known. Talk to your doctor.

PMID 37093160, PMID 28614793, PMID 37313955, Losartan prescribing information §12.3, dailymed.nlm.nih.gov

Propranolol: No study has looked at propranolol and CBD together. In healthy volunteers, CBD slowed some of the enzymes that break down propranolol (CYP1A2, CYP2C19); whether propranolol levels change is not known. Because CBD can lower blood pressure by a few mmHg, watch for dizziness and tell your doctor.

PMID 37313955, PMID 28614793

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

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

Strong enzyme inducers: These medicines can lower the level of CBD in the blood: with rifampin it fell by about one third. There are no direct measurements with others such as carbamazepine; the prescribing information expects a similar drop. Tell your doctor.

DailyMed Epidiolex label 7.1, EMA Epidyolex SmPC 4.5

Strong enzyme inducers: These medicines can lower the level of CBD in the blood: with rifampin it fell by about one third. There are no direct measurements with others such as carbamazepine; the prescribing information expects a similar drop. Tell your doctor.

DailyMed Epidiolex label 7.1, EMA Epidyolex SmPC 4.5

Ketoconazole: In a study with the THC/CBD mouth spray, ketoconazole raised CBD levels about 2-fold; with approved CBD taken by mouth, a similar strong medicine (itraconazole) raised CBD by less than 10%. Tell your doctor or pharmacist.

PMID 23750331, FDA Epidiolex label §12.3 (05/2026), PMID 38794183

Stomach protectors (PPIs): CBD can raise the blood level of omeprazole; no clinical importance has been reported. If you take it long term, tell your pharmacist.

PMID 37313955, EMA Epidyolex SmPC 4.5

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

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

Levothyroxine: In children with epilepsy taking levothyroxine, CBD blood levels were higher (about 2-fold in one study). If you take a thyroid medicine, tell your doctor.

PMID 33280111, PMID 37631333

Statins, birth control pills: No published human study was found that looked at these medicines and CBD together. The European patient information for approved CBD lists simvastatin among the medicines to tell the doctor about, because doses may need adjusting. It is still recommended that you tell your doctor about all the medicines you take.

PMID 41633759, EMA Epidyolex patient information section 2, EMA Epidyolex SmPC 5.2, Birth control pill prescribing information §7.1, dailymed.nlm.nih.gov

Diabetes medicines: CBD did not improve blood sugar or insulin results compared with placebo. Do not replace your diabetes medicines with CBD.

PMID 27573936, PMID 41167732

Another medicine that affects the liver: CBD itself can also raise liver enzymes: in healthy adults taking 5 mg/kg of CBD a day for 4 weeks, enzymes rose above 3 times the normal limit in 5.6% of participants. There are not enough data to judge the risk together with other medicines that can affect the liver. Tell your doctor.

EMA Epidyolex SmPC 4.4 and 4.5, FDA Epidiolex label §5.1 and §7.3 (05/2026), PMID 40622698

People taking prescription medicines: If you take medicines, talk to your doctor or pharmacist before starting CBD. The European and UK food authorities state that the safety of CBD in people taking medicines has not been established.

www.efsa.europa.eu, FSS/FSA 12.10.2023