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?
Jan 17, 2024- There is no known clinically significant interaction between ashwagandha and warfarin in humans.
- While some lab studies have shown ashwagandha may have mild blood-thinning effects, there is no clinical evidence that this causes problems when combined with warfarin.
- You should still talk with your doctor before taking ashwagandha with warfarin since data on herbal supplements is limited.
Answer
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.
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.
References & sources
Glossary — Terms in This Answer
- Anticoagulant
- A substance that prevents blood from clotting or reduces the ability of blood to form clots.
- Warfarin
- A prescription blood thinner medication commonly used to prevent dangerous blood clots.
- Ashwagandha
- An herbal supplement derived from a plant traditionally used in Indian medicine.
- Drug-herbal interaction
- A reaction that occurs when a medication and an herbal supplement affect each other's effectiveness or safety.
- Antiplatelet
- A substance that prevents platelets (cells involved in blood clotting) from sticking together.
- Bench research
- Scientific experiments conducted in a laboratory using isolated cells or tissues rather than in living organisms.
- In vitro
- Scientific research conducted in a laboratory setting outside of a living organism.
- In vivo
- Scientific research conducted within a living organism, such as animal or human studies.
Dr. Brian Staiger, PharmD
Doctor of Pharmacy, board certified clinical pharmacist (BCPS), American Herbalist Guild, Medication Therapy Management certified
Brian Staiger, PharmD, BCPS, is a licensed pharmacist with more than 13 years of experience across retail pharmacy, clinical pharmacy, medication safety, pharmacy program development, and healthcare administration. He is the founder of HelloPharmacist.com, where he helps patients...
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