Diet and Nutrition

Herbal Supplements: Can I Use Them During Chemotherapy?

July 25, 2017   /

I’ve taken herbs for a few years now. I am getting ready to start chemotherapy. Should I continue taking them?
You should probably stop taking your herbs before beginning chemotherapy or other cancer treatments, including surgery. Talk to your doctor or registered dietitian, and let them know what you are taking. Although many people think herbs are completely safe, they often contain active ingredients that can affect how other medications work. One concern is that herbs and other supplements can interfere with chemotherapy medications and make them less effective, or interact with medications and cause other medical problems. Some herbs can affect blood clotting, so if you have surgery the herbs could cause excess bleeding.

Which herbs can interact with my cancer treatments?
Because so many different herbal supplements and cancer medications are available, it is hard to make a specific recommendation without looking at each individual person. However, here are some examples:

  • St. John’s wort can decrease how well many medicines work in the liver, including some chemotherapy medicines
  • Many herbs, including garlic, ginger, and ginkgo, can increase the risk for excessive bleeding, which could cause a problem if you are having surgery
  • Herbs such as red clover and licorice are similar to the hormone estrogen—it is important not to use these while taking some medications prescribed for cancer survivors (always check with your doctor)  

Do some herbs enhance the immune system?
Studies on most herbs are mixed (echinacea, for example). Sometimes they are shown to enhance the immune system, while other studies disagree. Most claims made by herbal supplement manufacturers are not supported by the best scientific testing (clinical trials).

What are the other concerns and questions about herbal supplements?
Herbal supplements require no studies on safety before they are marketed. A few herbal supplements were removed from the market because of problems that were reported. Other questions pertain to:

  • The amount of active ingredients in herbal supplements
  • What dose is needed
  • Whether or not other potentially dangerous ingredients are included in the herbal supplement

What else should I know?
Making decisions about cancer treatment can seem overwhelming. Make sure you consider the possible negative effects of your supplements if you decide to continue taking them during treatment.


References and recommended readings
 American Cancer Society®. Dietary supplements: how to know what is safe. Available at: Accessed February 23, 2012.

Deng GE, Frenkel M, Cohen L, et al. Evidence-based clinical practice guidelines for integrative oncology: complementary therapies and botanicals. J Soc Integr Oncol. 2009;7:85-120.

Doyle C, Kushi LH, Byers T, et al. Nutrition and physical activity during and after cancer treatment: an American Cancer Society Guide for informed choices. CA Cancer J Clin [serial online]. 2006;56:323-353. Available at: Accessed February 23, 2012.

Mahan LK, Escott-Stump S, Raymond JL. Krause’s Food and the Nutrition Care Process. 13th ed. St Louis, MO: Elsevier Saunders; 2012:832-883.

National Institutes of Health, Office of Dietary Supplements. Dietary supplements: what you need to know. Available at: Accessed February 23, 2012.