Could the Herbs You’re Taking Cause Life-Threatening Bleeding?

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Blood Thinners

Some herbs like gingko biloba (pictured here) can thin the blood,
increasing the risk of excessive bleeding.

According to research performed at the Intermountain Medical Center in Salt Lake City, nearly half of older adults take herbal supplements regularly, yet most fail to tell their doctors about it. The supplements are natural, after all, so many believe they are completely harmless. Unfortunately, that’s not always the case.

Many herbs have the potential to not only interfere with other medications, but to increase the severity of side effects and cause excessive and even life-threatening bleeding. If an elderly woman taking a blood-thinning drug like warfarin, for example, started taking an herbal supplement as well, she could suffer serious consequences.

“The supplement could stimulate the liver to metabolize warfarin more effectively so she would end up with inappropriate low levels and risk the formation of a blood clot,” said Harvard Medical School cardiologist Elliott Anman, M.D., “or conversely, the supplement could increase the anticoagulant effect of the warfarin excessively and boost bleeding risk. Neither is good.”

Worse, many physicians don’t know what the side effects may be of taking certain herbs. According to a 2010 survey, over three-quarters of doctors themselves stated they were just as poorly informed about herbal medicines as the general public. Almost half rated their own knowledge as “quite” or “very” poor, and many said they rarely ask when reviewing patients’ medications whether they are taking herbal supplements.

That means that the general public needs to educate themselves, and be sure to speak up about the herbs they’re taking whenever they’re facing a medical procedure or fulfilling a new prescription.

Herbs That Can Increase Risk of Bleeding

Though there are many potential risks when taking herbal medications, in this post, we’ll focus on those that can exacerbate bleeding, or interfere with blood-thinning medications, since these are some of the most prescribed medications in the U.S. today.

To help reduce the risk of a heart attack or stroke, millions of Americans take blood-thinning medications like warfarin (Coumadin) and Pradaxa. These medications interfere with the body’s own ability to form blood clots, which makes it less likely that a clot will form and cause potentially deadly health problems. Because they interfere with clotting, however, these drugs can also increase the risk of excessive bleeding. Some patients taking Pradaxa, for example, have suffered gastrointestinal bleeding that led to death.

According to a 2010 study, of the 100 commonly used herbal and dietary supplements, 69 interfere with the effectiveness of warfarin. In fact, those participants combining the two were more often to experience problems, like higher rates of unexplained bleeding and a greater need for blood transfusions.

It’s paramount that patients taking these (and other) medications not compound the risk with herbs that can contribute to the blood-thinning properties of the anticoagulant. Potentially harmful herbs for those on blood-thinning medications include:

  • Gingko biloba
  • Garlic
  • Ginseng
  • Fish oil
  • Dong quai
  • Feverfew
  • Chamomile
  • Ginger
  • Nettle
  • Cayenne pepper
  • Bromelain

This is only a partial list of some of the herbs most likely to contribute to the blood thinning effects of medications. Some are more powerful than others, while diet, activity, and the dose of your medication can also play a part in your risk of bleeding.

Bottom Line

If you’re taking medications to “thin” your blood or reduce the risk of clots, you may want to check with a naturopath to see if there are other ways to control your risk of heart disease and stroke. Maybe there’s an alternative to prescription medications? Some people may be to go the natural route when reducing the risk of blood clots. A trained physician can help you combine a number of blood-thinning herbs to potentially achieve the same protection as a medication.

Next, tell your doctor about the herbs you’re taking. Regularly check your blood to see how your herbs may be affecting clotting ability. Those patients taking warfarin generally receive blood monitoring anyway, so you can talk to your doctor about your results and modify your dosage of the medication or the herbs to stabilize your bleeding risk.

Whatever you choose to do, the main thing is to be aware of the potential blood-thinning affects of certain herbal supplements. You don’t necessarily have to stop taking them—you just want to regularly monitor their effects so you’re not putting yourself at unnecessary risk.

Do you take blood-thinning medications and blood-thinning herbs? How do you manage the risks?

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Nissa Simon, “Most Patients Don’t Tell Their Doctors They Take Supplements,” AARP Bulletin, November 16, 2010,

Crystal Phend, “Herbal Medicines a Mystery to Most Doctors,” MedPage Today, April 7, 2010,

Intermountain Medical Center (2010, November 15). Danger of combining warfarin with herbal and dietary supplements revealed. ScienceDaily. Retrieved June 10, 2013, from­ /releases/2010/11/101115110955.htm.

Colleen M. Story

Colleen M. Story

Colleen M. Story, a northwest-based writer, editor, and ghostwriter, has been creating non-fiction materials for individuals, corporations, and commercial magazines for over 17 years. She specializes in the health and wellness field, where she writes and ghostwrites books, e-books, blogs, magazine articles, and more.

Colleen is the founder of Writing and Wellness. Her fantasy novel, “Rise of the Sidenah,” was released with Jupiter Gardens Press in September 2015. Her literary novel, “Loreena’s Gift,” is forthcoming in spring 2016 from Dzanc Books. She lives in Idaho.

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