Herbs and Chemotherapy

Question:

Can herbs interact with any of the chemotherapy drugs?

Answer:

The use of herbals in medicine dates back thousands of years. Herbal supplements sold to consumers are considered to be a "food" by the FDA, and therefore are not subject to the same testing, manufacturing, and labeling standards as prescription drugs. At the present time, the use of herbs together with chemotherapy has not been well studied. Currently there is not consistent and reliable information to determine if herbal supplements are safe or effective for someone with cancer. Moreover, the research on herbs that has been conducted uses a different form than what is available over the counter. In addition, there is potential for dangerous interactions between herbal supplements and chemotherapy. Many oncologists therefore advise their patients to avoid taking herbal supplements during chemotherapy.

Herbs can interact with chemotherapy drugs through a variety of different mechanisms.  Herbals are active compounds that require metabolism along the same pathways that chemotherapy and other prescription drugs require. As a result of this, herbs can change the way our bodies process medications. Some herbs can interfere with the metabolism of medications making them less effective. Other herbs may worsen the adverse effects and cause toxicity, by slowing down the metabolism of the chemotherapy.

Anticoagulants, such as warfarin, have a very narrow therapeutic range. They can cause adverse effects and are known to interact with other medications and dietary supplements.  Ginger, garlic, and turmeric are a few examples of herbs that can interfere with anticoagulants, increasing the risk of bleeding. In addition, some herbal supplements can cause excess bleeding and should be stopped if you are planning to have surgery.

Culinary herbs, on the other hand, when used in small quantities for flavoring, are generally safe. However, consuming large amounts for prolonged period of time may have adverse effects.  A registered dietitian can assist you to develop an individual plan that will support your health before, during, and after treatment.

It is critical that you discuss your interest in taking all complementary therapies with your medical team in order to avoid dangerous interactions

The original question and answer were generously donated by Diana Dyer, MS, RD a cancer survivor, registered dietitian, organic garlic farmer, and the author of "A Dietitian's Cancer Story: Information & Inspiration for Recovery & Healing from a 3-time Cancer Survivor.

Question and Answer updated by Lori Wyble, on behalf of the ON DPG

Page Updated: February 2014