Does Ashwagandha Interact With Warfarin?

In our latest question and answer, the pharmacist discusses the combination of warfarin and ashwagandha.


I am currently taking warfarin. Can I also take Ashwagandha?

Asked by Anthony On Jan 17, 2024

Answered by
Medical Content Reviewed By HelloPharmacist Staff

Published Jan 22, 2024
Last updated Apr 12, 2024

Key points

  • While ashwagandha doesn't seem to significantly affect blood clotting or have a clinically significant interaction with warfarin in humans, more research, especially in humans, may be needed due to the limited data on herbal supplements.
  • Always consult a doctor before adding supplements to your medication routine.


Thanks for taking the time to reach out to us!

According to our Drug-Herbal Interaction Checker, there is no known clinically significant interaction between ashwagandha and warfarin. However, let's take a closer look at this as there are sources online that report ashwagandha having mild anticoagulant effects.

No Interaction?

Warfarin is a blood thinner, specifically an anticoagulant, known for its numerous clinically significant drug interactions. Therefore, when combining it with over-the-counter supplements or herbal products, it's crucial to determine whether an interaction can occur.

Some supplements can increase the effectiveness of warfarin, raising the risk of bleeding events, while others can decrease its effectiveness, leading to negative outcomes.

Additionally, some supplements have blood-thinning effects on their own, which can be additive when combined with warfarin.

Regarding ashwagandha, it does not appear to significantly affect blood clotting, and there is no known clinically significant interaction with warfarin in humans.

It's important to note that while some animal studies have reported mild anticoagulant effects, there is no evidence of clinically significant anticoagulant effects in humans. A study published in 2022 by Baylor University Medical Center Proceedings reported as much:

Some supplements showed anticoagulant or antiplatelet properties in level 5 evidence (bench research), but we could find no clinical evidence for or against bleeding in these supplements. These supplements include ashwagandha, black pepper, dandelion, evening primrose, feverfew, honey, lavender, and lion’s mane.

Proc (Bayl Univ Med Cent). 2022; 35(6): 802–807.

The term 'bench research' refers to scientific research conducted in a laboratory setting, otherwise known as 'in vitro' research, rather than in animals or humans, which is known as 'in vivo' research.

Since there is no evidence to support ashwagandha causing blood thinning in humans to a clinically significant degree, and no evidence of an interaction with warfarin, that's why our interaction checker does not report an interaction.

Additional Thoughts

Although there have been no reported interactions between ashwagandha and warfarin in humans, it's important to remember that data on herbal supplements is generally somewhat limited, especially when compared to prescription medication.

As ashwagandha has shown at least a mild anticoagulant effect in some lab and animal trials, further trials in humans may be needed to better understand any risks.

As always, be sure to talk to your doctor about any supplement you are considering adding to your current medication so you can be appropriately monitored.


  • Adaptogenic and cardioprotective action of ashwagandha in rats and frogs, PubMed
  • Dietary supplements and bleeding, PubMed
  • Antiplatelet, anticoagulant, and profibrinolytic activities of withaferin A, PubMed
  • Withaferin A: From Ancient Remedy to Potential Drug Candidate, PubMed

About the Pharmacist

Dr. Brian Staiger, PharmD

Dr. Brian has been practicing pharmacy for over 13 years and has wide-ranging experiences in many different areas of the profession. From retail, clinical, program development, and administrative responsibilities, he's your knowledgeable and go-to source for all your pharmacy and medication-related questions! Dr. Brian Staiger also has herbalist training and educational certificates in the field of medical ethnobotany. Feel free to send him an email at [email protected]! You can also connect with Dr. Brian Staiger on LinkedIn.

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