Does Ashwagandha Interact With Warfarin?

Answer

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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.