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Treatment Types

Talking with Your Doctor About Dietary Supplements

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No matter what kind of cancer treatment you are getting, talk with your doctor before taking any new dietary supplement . If you have been taking supplements and want to keep taking them, it’s important that your doctor knows this, too.

Gather as much information as you can on the dietary supplement you are thinking about using. Then, talk with your cancer care team about it. Ask for their professional opinion as to whether taking the supplement is safe and medically sound. Also ask how it might be safely used along with your cancer treatment.

When talking to members of your cancer care team about using supplements, ask them:

  • Could the supplement provide me with some benefit?
  • Is it safe for me to take this supplement?
  • Could the supplement cause problems with my cancer treatment or other medicines I’m taking?
  • If I can take the supplement, how much should I take? How often should I take it? How long can I take it?
  • What side effects should I watch for?

Remember to make sure that your doctors know about all other medicines, vitamins, and supplements you’re already taking, as well. Some supplements can interact with your cancer treatment. For example, antioxidant supplements, such as vitamins C and E, might reduce the effectiveness of some chemotherapy or radiation treatments.

The American Cancer Society medical and editorial content team

Our team is made up of doctors and oncology certified nurses with deep knowledge of cancer care as well as editors and translators with extensive experience in medical writing.

Supplement Your Knowledge: Dietary Supplement Education Initiative 

This site includes fact sheets and videos about dietary supplements for the public, educators and healthcare professionals. Materials for the public are available in English and Spanish.

Office of Dietary Supplements, National Institutes of Health. What You Need to Know: Dietary Supplements. Accessed at on May 11, 2021.

Last Revised: August 30, 2021

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