The safety of herbal products and medicines

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 commonly used complementary and alternative therapies used by people with cancer. Some studies show that up to 6 out of 10 people with cancer (60%) use herbal medicine alongside conventional medical treatment. In this section of CancerHelp UK we have detailed information about herbal medicine 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 might help to prevent or relieve some symptoms of cancer and side effects of treatment. But they are not necessarily completely safe to use. Some herbal remedies can have serious and dangerous side effects.

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 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 treatments from your doctor, such as chemotherapy, radiotherapy, or hormone therapy. They may make the cancer treatments work less well or they may increase the effect, which could harm you. So we need results from large clinical trials to show which herbs are safe to use alongside conventional treatment. There is detailed information on what we currently know about the safety of herbal medicines on our herbal medicines page.

Remember that it is very important to tell your doctor about any herbal remedies you are thinking of taking, or are already using. Especially if you are having chemotherapy or radiotherapy, or are due to have surgery.