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Supplements and Blood Thinners: What to Avoid With Warfarin, Eliquis and Xarelto

Some supplements change how blood thinners work, so clear each one with your prescriber or pharmacist. On warfarin, keep vitamin K intake steady; vitamin K2 pills and St John's wort weaken warfarin (grade C and B). On apixaban or rivaroxaban, St John's wort lowers drug levels (grade B). Vitamin E raised bleeding strokes (grade B). Fish oil didn't raise bleeding in trials of people mostly not on blood thinners (grade A), but it is untested with apixaban.

Published How we grade evidenceEditorial policy

The short version

  • Grade B. St John's wort weakens blood thinners. It cut warfarin's effect on the INR clotting test (Jiang 2004) and left about a quarter less rivaroxaban in the blood (Scholz 2021).
  • Grade C. Vitamin K2 pills lowered the INR on a warfarin-type drug at doses below a typical pill (Theuwissen 2013). On warfarin, the advice is a steady vitamin K intake, not avoiding it (NIH ODS).
  • Grade A. In 11 large trials of people mostly not on blood thinners, fish oil did not raise bleeding; high-dose purified EPA, a prescription form, raised it a little. It has not been tested with apixaban or rivaroxaban (Javaid 2024).
  • Grade B. Vitamin E raised bleeding strokes by 22% in a meta-analysis of trials (Schürks 2010).
  • A 2022 review links ginkgo, turmeric, glucosamine and melatonin to bleeding in people on blood thinners, and garlic to bleeding in surgery (Hatfield 2022); dong quai more than doubled the INR in a case report (Page 1999).
SupplementWhat studies foundWhich blood thinnersGrade
St John's wortLowers drug effect or levelWarfarin, rivaroxaban; apixaban label says avoidB
Vitamin K or K2 pillsLowers the INR; steady intake mattersWarfarin and similar drugsC
Vitamin E22% more bleeding strokes in the general populationAny (adds to bleeding)B
Fish oilNo extra bleeding in trials of people mostly not on blood thinners; more with high-dose EPANot studied in people on anticoagulantsA
GinkgoNo change in clotting tests; reviews still list it as a bleeding riskAnyB
CranberryMixed: no change with juice, INR up with capsulesWarfarinC
GarlicNo extra bleeding with aged extract on warfarinWarfarinC
Glucosamine, dong quaiINR rises in case reportsWarfarinD

Which supplements should you avoid on blood thinners?

Blood thinners (anticoagulants) come in two kinds. Warfarin works by blocking vitamin K, so vitamin K and anything that changes how warfarin is cleared can move the INR, the blood test that tracks it. Apixaban (Eliquis), rivaroxaban (Xarelto), dabigatran and edoxaban, called DOACs (direct oral anticoagulants), don't depend on vitamin K. With them, the worries are supplements that add to bleeding and ones that lower the drug level.

A 2021 review found 78 herbs, foods and supplements reported to interact with warfarin, most by strengthening it, with bleeding up to fatal brain bleeds in some reports (Tan 2021). Good trials are scarce: a 2025 review of food and herbal interactions with all oral blood thinners found few randomized trials, small studies and conflicting results (Talasaz 2025). So most of what follows rests on small studies and case reports, and the safest rule is to clear every supplement with your prescriber or pharmacist. This guide covers anticoagulants; if you take aspirin or clopidogrel, ask your pharmacist about the same list.

Should you avoid vitamin K on warfarin?

No, keep it steady. NIH's Office of Dietary Supplements says that if you take warfarin, it is very important to get about the same amount of vitamin K each day (NIH ODS). A systematic review of 2 diet trials and 9 observational studies found conflicting evidence that food vitamin K moves the INR, and some studies suggested a minimum intake helps keep it stable (Violi 2016).

Grade C that vitamin K pills change warfarin's effect. Low-dose vitamin K has been tested as a deliberate add-on, under clinic care, to steady the INR. In 200 clinic patients on a warfarin-type drug, it barely changed time in the target range, though more people reached the most stable control (Rombouts 2007); pooling 4 such studies (678 people), a meta-analysis found a small benefit but not enough evidence to support routine use (Kramps 2013). Taken on your own, vitamin K2 is a different matter. In healthy volunteers on acenocoumarol, a warfarin-type drug, as little as 10 mcg a day of the K2 form MK-7, less than a usual 45 mcg pill, lowered the INR enough for hematologists to judge it clinically relevant in at least 40% of them (Theuwissen 2013). Don't start or stop vitamin K, vitamin K2 or a multivitamin that contains it without telling your anticoagulation clinic. Our vitamin K2 page has more.

Does St John's wort interact with blood thinners?

Grade B. Yes: it lowers their effect. In 12 healthy men, 2 weeks of St John's wort sped up warfarin's clearance and cut its effect on the INR (Jiang 2004). With rivaroxaban, it lowered drug exposure by 24% and the anti-clotting effect by 20% (Scholz 2021), and a review of DOAC interactions says people on these drugs should avoid St John's wort products (Grześk 2021). The apixaban label says to avoid it, because it lowers apixaban levels (FDA label); too little blood thinner raises the risk of a clot or stroke. More in can I take St John's wort with Eliquis?.

Is fish oil safe with blood thinners?

Grade A that fish oil didn't raise bleeding in trials of people mostly not on blood thinners. A 2024 meta-analysis of 11 randomized trials (120,643 people) found no more bleeding with omega-3s than without, including brain and gut bleeds. High-dose purified EPA, a prescription form, raised the relative risk by 50%, an absolute rise of 0.6% (Javaid 2024). Taking aspirin-type (antiplatelet) medicines did not change the result, but the review gives no separate results for people on anticoagulants, and no study has tested fish oil with apixaban or rivaroxaban; see can I take fish oil with Eliquis? and ask your prescriber.

Do ginkgo, turmeric, garlic or vitamin E raise bleeding?

  • Vitamin E, grade B. In the 7 trials that reported total stroke, it was unchanged with vitamin E, but in the 5 that reported them, bleeding (haemorrhagic) strokes rose by 22%, or one extra bleeding stroke per 1,250 people taking it (Schürks 2010). These were people in general, not people on blood thinners.
  • Ginkgo, grade B for no change in clotting tests. A meta-analysis of placebo-controlled trials of standardized extract found no change in platelet clumping or clotting times (Kellermann 2011), and in 12 healthy men ginkgo did not change warfarin's INR (Jiang 2005). Even so, reviews list ginkgo among supplements linked to bleeding in people on blood thinners (Tan 2021; Hatfield 2022).
  • Turmeric: a 2022 review ties turmeric to bleeding among people taking anticoagulants (Hatfield 2022), while a 10-day study of a curcumin product found no INR change on warfarin or dabigatran (Hu 2018). Nothing has been published with apixaban; see can I take turmeric with Eliquis?.
  • Garlic, grade C. In 48 people on warfarin, aged garlic extract for 12 weeks caused no extra bleeding (Macan 2006), and garlic did not change warfarin's effect in 12 healthy men (Mohammed Abdul 2008). The 2022 review still ties garlic to bleeding during surgery (Hatfield 2022).

What about cranberry, glucosamine and dong quai with warfarin?

  • Cranberry, grade C. In 30 people on warfarin, a daily 240 mL glass of cranberry juice for 2 weeks did not change warfarin levels and the INR differed on only one day (Ansell 2009). In 12 healthy men, a 2-week cranberry product raised the INR over time by about 30% (Mohammed Abdul 2008). A 2025 review judged up to a glass of juice a day safe with warfarin (Talasaz 2025); other cranberry products are less clear.
  • Glucosamine, grade D. A man stable on warfarin for 5 years saw his INR climb after raising his glucosamine-chondroitin, and the authors found 20 similar reports in an FDA database (Knudsen 2008).
  • Dong quai: in a case report, a woman stable on warfarin took dong quai for 4 weeks, and her INR more than doubled (Page 1999).

Can you take magnesium, B12, collagen or CoQ10 with Eliquis?

We found no studies or case reports of magnesium, vitamin B12, vitamin D, collagen or CoQ10 interacting with apixaban or rivaroxaban. That is an absence of evidence, not proof of safety, and the 2025 review notes how little anyone has tested (Talasaz 2025). Show your pharmacist the label, because blends often add vitamin K, vitamin E, fish oil or herbs, and check your stack against the upper limits.

What we'd skip on a blood thinner

Safety and interactions

  • Tell your prescriber, anticoagulation clinic or pharmacist before you start, stop or change any supplement. On warfarin, ask whether you need an extra INR check.
  • Change one product at a time, and keep the dose steady.
  • Before surgery or a dental procedure, tell the team every supplement you take; a 2022 review suggests stopping supplements you don't need 2 weeks ahead of surgery (Hatfield 2022). Don't stop your blood thinner unless the team tells you to.
  • Most supplements have never been tested with DOACs. "Not studied" is not the same as "safe".

When to see a doctor

Get emergency care for:

  • black or bloody stools, vomiting or coughing up blood;
  • a sudden severe headache, confusion, weakness on one side, or trouble speaking;
  • a fall or head injury while on a blood thinner;
  • chest pain, sudden breathlessness, or a swollen painful leg, which can mean a clot.

See your doctor soon for:

  • unusual bruising;
  • nosebleeds or gum bleeding that won't stop;
  • pink or brown urine;
  • an INR outside your range.

Don't stop a prescribed medicine on your own; ask the prescriber or pharmacist.

FAQ

What supplements should you not take with Eliquis? St John's wort, because it lowers apixaban levels and the apixaban label says to avoid it. Supplements that may add to bleeding, such as vitamin E, ginkgo and turmeric, need your prescriber's OK first. Most other supplements have never been tested with apixaban.

Can you take fish oil with blood thinners? In 11 large trials of people mostly not on blood thinners, fish oil did not raise bleeding (grade A). It has not been tested with apixaban or rivaroxaban, and high-dose prescription EPA raised bleeding a little, so ask your prescriber first.

Can I take vitamin K2 with warfarin? Not on your own. As little as 10 mcg a day of K2 lowered the INR in volunteers on a warfarin-type drug (grade C). Your anticoagulation clinic may add vitamin K on purpose, and then the key is a steady daily amount.

Is magnesium safe with blood thinners? We found no studies or case reports of magnesium interacting with apixaban or rivaroxaban. That is not proof of safety, so ask your pharmacist.

Do I have to avoid green vegetables on warfarin? No. NIH advises a steady vitamin K intake each day, not avoiding it, and studies on food vitamin K and the INR conflict.

Sources

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  2. Scholz I, et al. Effects of Hypericum perforatum (St John's wort) on the pharmacokinetics and pharmacodynamics of rivaroxaban in humans. Br J Clin Pharmacol. 2021. PubMed 32959922 · doi:10.1111/bcp.14553
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  4. Javaid M, et al. Bleeding Risk in Patients Receiving Omega-3 Polyunsaturated Fatty Acids: A Systematic Review and Meta-Analysis of Randomized Clinical Trials. J Am Heart Assoc. 2024. PubMed 38742535 · doi:10.1161/JAHA.123.032390
  5. Schürks M, et al. Effects of vitamin E on stroke subtypes: meta-analysis of randomised controlled trials. BMJ. 2010. PubMed 21051774 · doi:10.1136/bmj.c5702
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