CBD and blood thinners: what is known for each medicine?

Medicines and the importance of their interactions

From peer-reviewed publications and drug labels: the warnings, most important first. The same warnings also appear in the interaction checker. A medicine that is not listed can still interact with CBD.

Detailed pages: Warfarin and CBD

How does the interaction happen?

Not all blood thinners interact with CBD in the same way. Warfarin is broken down in the liver by several enzymes (CYP2C9, CYP1A2 and CYP3A4); a substance that slows these enzymes can make warfarin stay in the blood longer and raise the INR (a test that shows how long blood takes to clot). The cause of the INR rise seen in the cases is not known for certain; details are on the warfarin page. (Warfarin prescribing information §7 and §12.3, PMID 29387536)

Clopidogrel is a prodrug: to work, it must be converted in the liver, mostly by the CYP2C19 enzyme, into an active breakdown product. CBD slows this enzyme. For this reason, it is thought that with CBD less of clopidogrel's active product may form and the medicine's effect on platelets may be reduced; the US product information also gives this warning. (Clopidogrel prescribing information §5.1 and §12.3, FDA Epidiolex label §7.2 (05/2026), PMID 31724188)

Still, the picture is not simple. Most of clopidogrel is converted into an inactive product by enzymes called esterases (about 85% of the breakdown products in circulation). Laboratory studies showed that CBD can also slow one of these esterases (CES1). How much the two effects together change clopidogrel's effect has not been measured in patients. (Clopidogrel prescribing information §12.3, PMID 32591414)

According to their product information, all four DOACs are carried by P-gp (a transporter protein that pumps medicines out of cells); apixaban and rivaroxaban are also broken down by the CYP3A4 enzyme. The product information for approved CBD says that the levels of some P-gp medicines taken by mouth (everolimus, sirolimus, tacrolimus, digoxin) may rise with CBD. The DOACs are not named in this list and have not been measured together with CBD; this link is therefore only theoretical. (Apixaban prescribing information §7.1, Rivaroxaban prescribing information §7.1, Dabigatran prescribing information §12.3, Edoxaban prescribing information §12.3, EMA Epidyolex prescribing information 4.5, FDA Epidiolex label §7.2 (05/2026))

What do studies and official drug information say?

Each finding shows the type of evidence it rests on. A case report describes a single patient; it does not prove cause and effect.

1. Case report

   Warfarin: INR rose in case reports (2018, 2020)

   In two epilepsy patients who started approved CBD, INR rose; to keep INR in the target range, the warfarin dose had to be lowered by about 30% and 20%. In one patient using cannabis containing THC, INR also rose to 4.6. Details of the cases, monitoring and frequently asked questions are on the warfarin page.

   Source: PMID 29387536, PMID 33016308, PMID 30326170

2. Systematic review

   All blood thinners: no data except for warfarin (2023)

   A systematic review of interactions between cannabinoids and blood thinners found only 7 cases, all involving warfarin; INR rose in 6 of them. The authors reported that there was no evidence supporting an interaction with blood thinners other than warfarin and that the quality of the available data was very low.

   Source: PMID 37740600

3. Official drug information

   Clopidogrel: the US product information says effectiveness may be reduced

   The US product information for approved CBD (05/2026) gives clopidogrel as an example of CYP2C19 medicines whose effect comes largely from an active breakdown product: when used with CBD, the blood level of this product and the medicine's effectiveness may be reduced. The European product information does not name clopidogrel. A review of cannabis interactions with blood thinners and platelet medicines also describes only a mechanism-based possibility for clopidogrel.

   Source: FDA Epidiolex label §7.2 (05/2026), EMA Epidyolex prescribing information 4.5, PMID 31724188

4. Official drug information

   Clopidogrel's package insert: medicines that block CYP2C19 reduce its effect

   Clopidogrel's product information states that omeprazole and esomeprazole, which block CYP2C19, clearly reduced clopidogrel's effect on platelets in clinical studies, and that they should not be used together with it. CBD is not on this list; whether CBD's effect is as large as that of these medicines is not known.

   Source: Clopidogrel prescribing information §5.1 and §7.2

5. Drug-level study

   A CBD-dominant cannabis extract also slowed CYP2C19 in humans (2023)

   CBD slowing CYP2C19, the enzyme that activates clopidogrel, has also been shown in humans. In 18 healthy volunteers, a single dose of a CBD-dominant cannabis extract (640 mg CBD and 20 mg THC) increased the total amount in the blood (AUC) of omeprazole, which is broken down by the same enzyme, about 3-fold. In a study with approved CBD, the active breakdown product of clobazam, which is broken down by CYP2C19, also rose about 3-fold. Clopidogrel itself was not included in these studies.

   Source: PMID 37313955, FDA Epidiolex label §7.2 and §12.3 (05/2026)

6. Systematic review

   Apixaban, rivaroxaban, dabigatran, edoxaban: no human data

   No published study or case looking at these four medicines together with CBD could be found. The product information for approved CBD does not name these medicines; it only states in general terms that levels of P-gp medicines taken by mouth may rise. This warning is based on CBD raising the level of everolimus, another P-gp medicine, about 2.5-fold in healthy volunteers. A lack of data does not mean that CBD is safe with these medicines.

   Source: PMID 37740600, FDA Epidiolex label §7.2 (05/2026), EMA Epidyolex prescribing information 4.5

What is monitored?

• Warfarin: INR is measured more often when starting CBD, when changing the amount of CBD, and when stopping CBD. Your doctor decides how often it is measured. (Warfarin prescribing information §5.1, PMID 29387536, PMID 33016308) CBD and warfarin: detailed page
• Signs of bleeding (with any blood thinner): unexpected or prolonged bleeding or bruising; bleeding gums or frequent nosebleeds; heavier than usual menstrual bleeding; red, pink or brown urine; red or tar-black stools; coughing up blood or vomit that looks like coffee grounds; headache, dizziness or weakness. If you notice any such sign, tell your doctor right away. (Apixaban patient information, Warfarin prescribing information)
• Clopidogrel: do not stop clopidogrel or change its dose on your own; the product information states that stopping the medicine early may increase the risk of a heart attack. If you want to use CBD, discuss it with the doctor who prescribed clopidogrel; your doctor will review your treatment accordingly. (Clopidogrel prescribing information §5.3 and §17, FDA Epidiolex label §7.2 (05/2026))
• What is in the product: an INR rise has also been reported with cannabis containing THC. Find out the amount of CBD and THC in the product you use from its label and its certificate of analysis. (PMID 30326170, PMID 37740600) How to read the label and certificate of analysis

Frequently asked questions

References

Last reviewed: October 27, 2026. On this date, each source was opened and checked against the related sentence.