The safety of herbal products and medicines | Cancer Research UK
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The safety of herbal products and medicines

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This page has information about the safety of herbal health products and medicines. You can read about


What herbal medicine is

Herbal medicine uses plants, or mixtures of plant extracts, to treat illness and promote health. It is sometimes called phytomedicine or phytotherapy. Herbal medicine is one of the most common complementary and alternative therapies used by people with cancer. 

Some studies show that many people with cancer use herbal medicine alongside conventional medical treatments such as radiotherapy, chemotherapy or biological therapy. 

You can read our detailed information about herbal medicine and cancer.


Herbal medicines and cancer

Many herbal medicine products can be bought over the counter and are marketed as natural or herbal. There is some evidence that herbal products can help to prevent or relieve some symptoms of cancer and the side effects of treatment.


Using herbal remedies during cancer treatment

Before taking any type of herbal medicine, it is very important to discuss it with your cancer doctor, specialist nurse, GP or pharmacist. Herbal products should be used carefully. They are medicines. And like any medicine they have effects on the body and can cause side effects. 

It is very important to use only herbal products that are registered under the Traditional Herbal Remedies (THR) scheme. Remedies that are registered under the scheme have a THR mark and symbol on the packaging. THR products have been tested for quality and safety. 

Some herbal remedies may interact with cancer treatments such as chemotherapy, radiotherapy, biological therapy or hormone therapy. Some herbal therapies could make particular cancer drugs work less well or they may increase the side effects. We don't yet know very much about these interactions or side effects. So we need results from large clinical trials to show which herbs are safe to use alongside conventional treatment. 

There is some information on what we currently know about the safety of herbal medicines on our herbal medicines page.

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Updated: 24 October 2014