Cayenne Pepper and Warfarin

According to, peppers are among the most commonly used spices in the world, and people in some Southeast Asian countries consume an average of 5 g red pepper per day 1. However, a major safety concern is the potential for an interaction between cayenne pepper and some medicines, including warfarin 3. Interactions with warfarin are potentially serious because small changes in warfarin blood levels can have harmful effects. Consult with your doctor before using cayenne peppers medicinally.

Is This an Emergency?

If you are experiencing serious medical symptoms, seek emergency treatment immediately.

About Warfarin

Warfarin is in a category of medicines called anticoagulants, which means it slows the body’s blood clotting process. You may be taking warfarin if you have blood clots in your veins or lungs. Warfarin is also used by people who have an irregular heart rhythm called atrial fibrillation, which can cause dangerous blood clots to form in the body. It is also prescribed to prevent stroke in some people.

How It Works

The active component in cayenne peppers is capsaicin. Capsaicin works to alleviate pain by blocking a chemical called substance P, which is responsible for transmitting pain messages to the brain. When substance P is inhibited, pain signals no longer go to the brain and the person experiences pain relief. Capsaicin produces only a short-term effect on substance P, so people need to keep taking it to sustain the pain relief.

Interaction With Warfarin

A report published in “American Journal of Health-System Pharmacy” in 2000 supported the interaction between warfarin and capsaicin 34. Cayenne pepper increases the time blood needs to clot, and when taken with anticoagulant medicines like warfarin, the effect of the medicine may be intensified, says This increases the risk of uncontrolled bleeding, which can present as symptoms such as bloody urine or stool, spitting up blood, unusual bruising and continued bleeding from minor cuts.

Other Considerations

You may experience a similar effect if you take cayenne pepper with other herbs that decrease blood clotting, such as:

  • garlic
  • ginger
  • ginkgo
  • ginseng
  • horse chestnut
  • red clover
  • saw palmetto