CBD and Blood Thinners (e.g. Warfarin, Eliquis)
David ReichUpdated:Key points at a glance:
CBD may influence the way blood thinners work. With warfarin, CBD can inhibit the enzyme CYP2C9, which may slow down the breakdown of the medicine. This can be associated with a rise in INR and a potentially increased risk of bleeding. For Eliquis (apixaban), a possible interaction is discussed via CYP3A4 and P‑gp, although the available data are limited. Similar considerations apply to phenprocoumon. The recommended approach is to consult a doctor. For those taking warfarin, INR is often checked before starting CBD and again after 3 to 7 days. For those taking Eliquis, attention should be paid to any signs of bleeding.
CBD is often mentioned in connection with possible health‑related uses, but it is important to consider potential interactions with other medicines, particularly blood thinners such as warfarin and Eliquis (apixaban). If you are taking anticoagulants, safety and close medical supervision are essential.
CBD and blood thinners (warfarin, Eliquis): short answer
CBD may increase the effect of warfarin because it can inhibit its breakdown via CYP2C9. Possible result: INR increase and a higher tendency to bleed. With Eliquis (apixaban) the risk is currently theoretical (CYP3A4/P‑gp), and clinical data are limited. Only start CBD after consulting your doctor. While taking warfarin: check INR before and 3–7 days after starting CBD; while taking Eliquis: watch for signs that could indicate bleeding.
What are warfarin and Eliquis?
Warfarin and Eliquis are two commonly used blood thinners (anticoagulants) that are prescribed to reduce the risk of blood clots and stroke. Warfarin, also known under the brand names Coumadin and Jantoven, is widely used. Eliquis, whose active substance is apixaban, is also used in many countries.
How do warfarin (VKOR) and Eliquis (factor Xa) work?
Warfarin (Coumadin, Jantoven)
Warfarin inhibits vitamin K epoxide reductase (VKOR). As a result, the activity of the vitamin K‑dependent clotting factors II, VII, IX and X is reduced – the clotting process is slowed down.
Eliquis (apixaban)
Apixaban is a direct factor Xa inhibitor. It blocks factor Xa in the coagulation cascade and acts independently of vitamin K.
Warfarin reduces vitamin K‑dependent clotting factors (via VKOR), while Eliquis (apixaban) directly blocks factor Xa. Both slow blood clotting, but via different mechanisms, which matters when considering CBD interactions.
What is CBD and how does it work in the body?
CBD (cannabidiol) is one of many compounds found in the cannabis plant. It is discussed as an option in a range of contexts and interacts with the body’s endocannabinoid system, a complex system involved in many important processes, including mood, sleep and appetite.
Read our article here on how CBD works in the body
How CBD affects drug metabolism (CYP enzymes and P‑gp)
CBD can inhibit drug‑metabolising enzymes in the liver, especially CYP2C9 and CYP3A4. CBD can also to some extent influence the transport protein P‑glycoprotein (P‑gp). These mechanisms are relevant for anticoagulants:
- Warfarin is mainly broken down via CYP2C9 (S‑enantiomer) and CYP3A4/CYP1A2 (R‑enantiomer).
- Apixaban (Eliquis) is metabolised via CYP3A4/5 and is a substrate of P‑gp.
If breakdown is inhibited, drug levels can increase – with a potentially higher bleeding tendency. This is a key pathway for CBD drug interactions with prescription medicines.
Interactions between CBD and blood thinners
CBD and warfarin: documented interaction (CYP2C9)
For CBD and warfarin, there are published case reports of interactions. By inhibiting CYP2C9, CBD can increase warfarin levels, raise the INR and thereby increase the tendency to bleed. Case reports describe a marked INR rise after starting CBD oil, in some instances with a need to reduce the warfarin dose.
CBD and Eliquis (apixaban): theoretical interaction (CYP3A4/P‑gp)
For CBD and Eliquis or CBD and apixaban, the data are currently limited. Apixaban is broken down via CYP3A4/5 and is a P‑gp substrate. Strong inhibitors of these pathways (for example ketoconazole, itraconazole, ritonavir) can substantially increase apixaban levels. CBD is not considered a strong inhibitor; however, a theoretically plausible increase in levels cannot be ruled out, especially at higher CBD doses or with full‑spectrum products.
Note on phenprocoumon
In some regions, phenprocoumon (for example Marcumar) is prescribed instead of warfarin. The interaction logic via CYP2C9 is similar – close INR monitoring when starting CBD is also advisable here.
CBD can inhibit liver enzymes (CYP2C9, CYP3A4) and affect P‑gp. With warfarin and phenprocoumon, interactions are documented and can raise INR. With Eliquis (apixaban), the interaction is theoretically possible via CYP3A4/P‑gp, but clinical evidence is still limited.
Check for potential CBD interactions with other prescription medicines here:
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Comparison: CBD and blood thinners (overview)
| Medicine | Mode of action | Metabolism | Interaction with CBD | What to do? |
|---|---|---|---|---|
| Warfarin | VKOR inhibitor | Mainly CYP2C9 (S‑), CYP3A4/1A2 (R‑) | CBD may increase levels/INR | Check INR before/after starting CBD, inform your doctor |
| Eliquis (apixaban) | Factor Xa inhibitor | CYP3A4/5, P‑gp | Risk theoretical; data limited | Watch for bleeding, avoid strong CYP3A4/P‑gp inhibitors |
Recognising risks: signs of bleeding and monitoring
If you are combining CBD with warfarin, phenprocoumon or Eliquis, monitoring for signs of bleeding is important:
- Unusual bruising, frequent nosebleeds or bleeding gums
- Pink/red urine, black (tarry) stools
- Prolonged nosebleeds, coughing up blood
- Sudden severe headaches, dizziness, weakness, speech or visual disturbances
Warfarin/phenprocoumon: Keep within the INR target range, attend regular checks, keep vitamin K intake consistent.
Eliquis: No INR checks are required, but adherence to the prescribed regimen is essential, and care is needed when using additional CYP3A4/P‑gp inhibitors or inducers.
Safe use of CBD with blood thinners: 5‑step checklist
- Inform your doctor: Share which anticoagulant you take (warfarin, phenprocoumon, Eliquis/apixaban), the dose, indication, and the CBD product and dose you are considering.
- Baseline assessment: Warfarin/phenprocoumon → check INR before starting CBD. Eliquis → review your full medicine list (including supplements) for CYP3A4/P‑gp interactions and note any existing bleeding symptoms.
- Start low, go slow: Begin with a low CBD dose and increase slowly using a consistent product at a consistent time of day. See the CBD dosage guide.
- Monitoring: Warfarin/phenprocoumon → check INR after 3–7 days and with every CBD dose change, as advised by your doctor. Eliquis → closely watch for signs of bleeding and review other CYP3A4/P‑gp inhibitors with your healthcare provider.
- If something changes: If you notice anything unusual (for example new bleeding, bruising, dizziness or black stools), pause CBD and seek medical advice; medicine doses may need adjustment.
Use CBD with blood thinners only under medical supervision: document your medicines, start with a low CBD dose, monitor INR where relevant, and watch carefully for signs of bleeding or other changes.
When you should seek urgent medical help
- Severe, persistent bleeding or large, unexplained bruises
- Black, tarry stools or blood in your urine
- Sudden severe headaches, dizziness, weakness, speech or visual disturbances
Side effects of CBD
CBD (cannabidiol) is generally reported as being well tolerated. Commonly reported effects include tiredness, diarrhoea, changes in appetite/weight and dry mouth. At higher doses, CBD can raise liver enzyme values (ALT/AST), particularly in combination with medicines that affect the liver. Importantly, CBD can influence CYP enzymes – this is the main pathway for CBD drug interactions with blood thinners and other prescription medicines. Topical CBD products (for example creams) usually have low systemic absorption and therefore a lower interaction potential.
Read our article here on CBD side effects
Side effects of blood thinners
Anticoagulants are important medicines but require careful monitoring. The main side effect is an increased tendency to bleed, especially if the effect is too strong, additional inhibitors (for example strong CYP3A4/P‑gp inhibitors) are used, or injuries occur. With warfarin/phenprocoumon, a stable INR target range is crucial; with Eliquis, adherence to treatment and recognition of potential bleeding signs are important.
Both CBD and blood thinners can affect how your blood clots. Anticoagulants increase bleeding risk by design, and CBD can alter drug metabolism via CYP enzymes. Combining them requires individual medical advice and ongoing monitoring.
Mini glossary
- INR: Blood value used to assess the degree of anticoagulation with warfarin/phenprocoumon.
- CYP: Liver enzymes (for example CYP2C9, CYP3A4) that metabolise medicines.
- P‑gp: Transport protein (P‑glycoprotein) that pumps substances out of cells.
Read our article here on CBD drug interactions
Conclusion: CBD with warfarin or Eliquis
CBD is discussed as an option for various complaints, but its use together with blood thinners needs caution. With warfarin/phenprocoumon, a CYP2C9‑mediated interaction has been reported – with a possible INR increase and higher bleeding tendency. With Eliquis (apixaban), the CBD interaction risk is currently theoretical (CYP3A4/P‑gp); clinical evidence is limited. Use CBD only with medical guidance, monitor values and/or symptoms, and start with a low CBD dose.
Disclaimer: This article is for information purposes only and does not replace medical advice. Do not change medicines or dosages without consulting your doctor. No claims are made regarding the treatment or cure of illnesses.