Herbal Remedies and Cancer Treatment

One week before you have surgery or start chemotherapy or radiation therapy, you must stop taking any herbal or botanical home remedies or other dietary supplements because they can:

  • Interact with your other medications.
  • Increase or lower your blood pressure.
  • Thin your blood and increase your risk of bleeding.
  • Make radiation therapy less effective.
  • Lower the effects of medications that weaken the immune system.
  • Increase the effects of sedation or anesthesia (medications to make you sleepy).

Common Herbs and Their Effects


  • Can cause an allergic reaction, such as a rash or difficulty breathing.
  • Can lower the effect of medications used to weaken the immune system.


  • Can lower your blood pressure, fat, and cholesterol levels.
  • Can increase your risk of bleeding.

Gingko (also known as Gingko biloba)

  • Can increase your risk of bleeding.


  • Can act as a stimulant, which can decrease the effects of anesthesia or sedation (medications to make you sleepy).
  • Can increase your risk of bleeding.
  • Can lower your blood glucose (sugar) level.


  • Can make chemotherapy less effective.

St. John’s Wort

  • Can interact with medications given during surgery.
  • Can make your skin more sensitive to radiation or laser treatment.


  • Can increase the effects of anesthesia or sedation (medications to make you sleepy).

Herbal formulas

  • Many herbal formulas contain different herbs. We don’t know their side effects. You must also stop taking these products 1 week before and during treatment.

For more information about herbs and botanicals, visit the MSK Integrative Medicine Service website at www.aboutherbs.com.

This information does not cover all possible side effects. Please share any questions or concerns with your healthcare provider.

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