Last updated: 11 November 2026
CBD can interact with some blood thinners. The clearest evidence is with warfarin: in case reports, INR rose after people started prescription CBD, and their warfarin dose had to be cut. For apixaban, rivaroxaban, clopidogrel and aspirin the risk is mostly theoretical. Check with your GP, anticoagulant clinic or pharmacist before starting CBD.
Below: each blood thinner, other supplements to watch and the bleeding signs that need help. This is general information, not medical advice.
Can you take CBD with blood thinners?
Only after checking with whoever looks after your blood thinner. Warfarin has the most evidence of an interaction: case reports show INR rising when prescription CBD was started, needing warfarin dose cuts of about 20% to 30%. For newer blood thinners and antiplatelets there are no published studies, so any risk is based on how the medicines are processed.
The Food Standards Agency (FSA) advises, as a precaution, that people taking any medication should not use CBD unless under medical direction. For other medicines, see which medicines interact with CBD.
Blood thinners and CBD: what is known
Strength of evidence: moderate means case reports in people; limited means prediction from how the medicine is processed, with no studies of CBD.
| Medicine | How it is handled | What is known with CBD | Evidence | What to do |
|---|---|---|---|---|
| Warfarin | Mainly CYP2C9, plus CYP3A4 and others | INR rose in case reports at high prescription doses; warfarin cut by about 20% to 30% | Moderate (very low-quality evidence) | Tell your anticoagulant clinic first and expect extra INR checks |
| Apixaban, rivaroxaban (DOACs) | CYP3A4 and the gut pump P-gp | No studies. CBD affects gut P-gp, so a rise is possible in theory | Limited | Ask your GP or pharmacist first |
| Edoxaban, dabigatran (DOACs) | Mainly P-gp | No studies. Levels could rise in theory by the P-gp route | Limited | Ask your GP or pharmacist first |
| Clopidogrel (antiplatelet) | Activated by CYP2C19 | No studies. CBD blocks CYP2C19, so clopidogrel could work less well in theory | Limited | Ask your prescriber first, especially if you have a stent |
| Ticagrelor (antiplatelet) | CYP3A4 and P-gp | No studies | Limited | Ask your GP or pharmacist first |
| Low-dose aspirin | Broken down mainly by other enzymes, not the CYP route | No known interaction | Limited | Check with a pharmacist, especially if you take other blood thinners too |
iThis isn’t a complete list. Always check your own medicines with a pharmacist.
Can you take CBD with warfarin?
Only with your anticoagulant clinic’s agreement and closer INR checks. Warfarin is broken down mainly by CYP2C9, an enzyme CBD blocks in lab tests, and the Epidyolex product information names warfarin as a medicine whose levels CBD may raise.
The evidence in people comes from case reports. In one, a patient’s INR climbed to 6.86 as prescription CBD was increased, and his weekly warfarin dose had to be cut by 30%. In another, a 46-year-old man needed a warfarin cut of nearly 20% to keep his INR in range. A 2023 systematic review found seven such reports and rated the evidence very low quality, with CBD doses above 600mg a day where known.
What to do: tell your anticoagulant clinic before you start, keep the amount steady, and tell them if you stop, as INR could fall again. The NHS also says to avoid St John’s wort, vitamin K supplements and cranberry products on warfarin.
CBD with apixaban or rivaroxaban
No studies or case reports have looked at CBD with apixaban or rivaroxaban. Both are processed partly by CYP3A4 and carried by a pump in the gut wall called P-gp. CBD didn’t change CYP3A4 activity in a study in healthy volunteers, but it raised the transplant medicine everolimus about 2.5-fold through the P-gp route, so a rise is possible in theory.
There is no routine blood test like INR to show a change, and the NHS asks you to tell your doctor or pharmacist about any supplements before taking apixaban. Edoxaban and dabigatran rely more on P-gp, so the same caution applies.
Can you take CBD with clopidogrel?
Ask your prescriber first. Clopidogrel is inactive until the liver enzyme CYP2C19 turns it into its active form. The MHRA advises against taking omeprazole or esomeprazole with clopidogrel because they block CYP2C19 and reduce the active medicine.
CBD also blocks CYP2C19 in people, so in theory it could make clopidogrel less effective. No study has tested this, and supplement amounts are far below the doses studied. After a heart attack or stent, clear it with your cardiology team or GP, and never stop clopidogrel on your own.
Can you take CBD with aspirin?
iThere is no known interaction between CBD and low-dose aspirin, which is broken down mainly by enzymes other than the CYP group. The bigger bleeding risk comes from combining aspirin with other blood thinners or with painkillers such as ibuprofen, so check with a pharmacist.
Does CBD thin your blood?
We found no good evidence that CBD at supplement amounts thins the blood in people. The concern is different: CBD may change how the body handles the medicine, which could raise or lower its effect.
Does the amount of CBD matter?
Yes. Where the dose was known, the warfarin cases involved more than 600mg of CBD a day, around 60 times the FSA’s 10mg a day advice. A 2023 review suggested relevant CBD interactions are likely only above about 300mg a day. But supplement amounts haven’t been tested with blood thinners, so caution still applies. See our guide to the FSA’s 10mg advice.
Other supplements and blood thinners
Several supplements are a bigger known concern with blood thinners than CBD. Check these too:
- Turmeric, including CBD oils that contain it (our Relief CBD Oil contains turmeric and black pepper): see turmeric side effects and who should avoid it and CBD and turmeric together.
- Vitamin K, including K2, which works against warfarin: see vitamin K2 and warfarin.
- Fish oil and omega 3 at high doses: see omega 3.
- Vitamin E at high doses: see vitamin E.
- St John’s wort, which lowers levels of warfarin and DOACs: see St John’s wort interactions.
Having an operation or a dental extraction? Tell the team about any CBD as well as your blood thinner: see CBD before surgery.
What to ask your GP or anticoagulant clinic
Take the CBD product with you, or a photo of the label showing how much CBD it gives, and ask:
- Is CBD a reasonable idea with my blood thinner, and at what amount?
- On warfarin: how soon should I have an extra INR check after starting, and after stopping?
- On a DOAC or clopidogrel: what should I watch for?
Other medicines too? See CBD and antidepressants (SSRIs add to bleeding risk with blood thinners), CBD and blood pressure medication and CBD for older adults.
Bleeding warning signs
Call 999 if you have a sudden bad headache with confusion, slurred speech or weakness in an arm or leg (possible bleeding in the brain), heavy bleeding that won’t stop, or you’re vomiting or coughing up blood.
Stop CBD and call NHS 111 or your GP if you notice blood in your pee or poo, black poo, unexplained bruising, nosebleeds or bleeding gums, or after any head injury, even a minor one. Also get advice if you feel faint or severely dizzy.
For CBD’s own side effects, see CBD side effects.
If your GP or pharmacist says CBD is OK
The FSA’s 10mg a day figure is precautionary advice rather than a legal limit, set while longer-term safety research continues. At Evopure we think it is a very cautious figure, and many adults use more. If you go above it, increase slowly, and check with your GP or pharmacist first if you take any medication.
With a blood thinner, a fixed amount taken the same way every day is easiest for your clinic to plan around.
Next step
CBD Capsules Broad Spectrum
Only with your GP’s, clinic’s or pharmacist’s OK: Broad Spectrum CBD Capsules give a measured dose, one 10mg capsule, in a vegan capsule with 0% THC, alcohol-free, with no turmeric, and third-party lab tested. 30 capsules per jar.
Add Broad Spectrum CBD Capsules 10mg to bag or choose another strength
Subscribe and save 25% on your first order, then 20%. New to Evopure? Join our emails for 20% off a one-off first order. Free UK delivery over £40. The FSA advises healthy adults to take no more than 10mg of CBD a day: one 10mg capsule gives 10mg. Adults only. If you take a blood thinner or any other medicine, check with your GP, anticoagulant clinic or pharmacist first. We don’t recommend our products during pregnancy or breastfeeding.
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View productSources 10
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- Grayson L et al. An interaction between warfarin and cannabidiol, a case report. Epilepsy Behav Case Rep, 2018.
- Cortopassi J. Warfarin dose adjustment required after cannabidiol initiation and titration. Am J Health Syst Pharm, 2020.
- Smythe MA et al. Anticoagulant drug-drug interactions with cannabinoids: a systematic review. Pharmacotherapy, 2023.
- Herdegen T, Cascorbi I. Drug interactions of tetrahydrocannabinol and cannabidiol in cannabinoid drugs. Dtsch Arztebl Int, 2023.
- MHRA. Clopidogrel and proton pump inhibitors: interaction, updated advice. Drug Safety Update.
- NHS. Warfarin.
- NHS. Apixaban.
- NHS. Clopidogrel.
- Food Standards Agency (GOV.UK). Cannabidiol (CBD) guidance.
