The safety of complementary and alternative therapies | Cancer Research UK
Cancer Research UK on Google+ Cancer Research UK on Facebook Cancer Research UK on Twitter

The safety of complementary and alternative therapies

Nurse and patients talking about cancer

This page has information about the safety of complementary and alternative therapies. There is information about


Safety of complementary therapies in cancer care

Many complementary therapies are safe to use alongside conventional cancer treatments such as radiotherapy or cancer drugs. Some complementary therapies can help to reduce symptoms and side effects and help people to feel better. But some types might not be safe in certain situations. 

Some complementary therapies might stop conventional treatments working as well as they should. For example, there is some concern that taking antioxidants during chemotherapy or radiotherapy could protect the cancer cells from being damaged by the cancer treatment. At the moment there is not enough evidence to know for sure whether antioxidants are helpful or harmful in this situation. We need more research to help us find out about the best ways to use complementary therapies.

The safety of any complementary therapy will depend on which therapy it is, and on the type of conventional treatment you are having. It is always important to talk to your doctor about any complementary therapies you are thinking of using. You need to tell your doctors before you start taking the complementary therapy, especially if you are in the middle of a course of cancer treatment. 

You can read about conventional cancer treatments.

Most cancer doctors will support patients using one or more of the many types of complementary therapies. Sometimes, doctors may recommend that you use them. It is also important to tell your complementary therapist about your cancer treatment.

Remember that therapies may have side effects. It is important to know what the possible side effects are before you start using them. To find out about the possible side effects and any precautions you may need to take with particular therapies, you can read our pages about specific therapies.


Safety of alternative cancer therapies

Despite research into various types of alternative therapy, there is no scientific or medical evidence to show that alternative therapies can help to treat or cure cancer. Some alternative therapies may be harmful and cause side effects or interfere with your conventional cancer treatment. They may cost a lot of money.

Therapists who promote alternative therapies and companies that sell the therapies can cause harm by convincing people that an alternative therapy will cure them when it can’t. This can be especially harmful if a person is also encouraged to give up their conventional cancer treatment. 

Some therapists and companies that promote alternative therapies rely on reports of individual experiences from people who say that a therapy has helped them. For scientists and cancer doctors, this is not enough. It doesn't prove anything. New therapies and potential cancer treatments need to be compared with accepted and proven ones before we can be sure of their benefit. The best way to do this is by using properly organised clinical trials just like those used for conventional cancer treatments.

Unfortunately, some alternative therapies are just money making schemes. Companies or individual people charge a lot of money for something that has not been properly tested, or has not been shown to work in clinical trials or scientific studies. This is very unfair on people with cancer, who may be very vulnerable. People in this situation may be willing to try anything if they think that there is a chance that it will help to cure them. Do be very wary of anything you find for sale on the internet.

If you are considering stopping conventional cancer treatment to try an alternative therapy it is very important that you discuss this with your treatment team first. Even when a cancer can't be cured with conventional treatments, your doctor will still be able to help to control symptoms such as pain and sickness using conventional medicine. So it is important to stay in touch with your doctor and discuss treatment possibilities with them. 

When we publish information about alternative treatments that haven’t been properly tested, we are sometimes accused of trying to prevent people with cancer from getting effective treatment. This is not what we want to do. People can end up paying a great deal of money for some of these so called cancer cures. This is one of our main concerns. Our message is

  • Be very careful
  • Make sure that you look into the information that is available
  • Talk to your own cancer doctor before you buy anything

Telling your doctor about using a therapy

If you are considering using an alternative therapy or complementary therapy it is very important to tell your cancer doctor, specialist nurse, pharmacist or GP. Many people using complementary and alternative cancer therapies don’t tell their doctors. This may be because their doctor didn’t ask them so they didn’t mention it. Or they may worry that their doctor will tell them to stop using the therapy.

You may not think that it is important for your doctor or nurse to know about these therapies. But some therapies could possibly interact with your cancer treatments and make them work less well or increase the side effects. You need to be especially careful with some dietary supplements such as vitamins, minerals and herbal products. 

If your doctor has any concerns about the type of therapy you are using they can discuss this with you. It is equally important to tell your complementary therapist about your conventional cancer treatment. 

Many health professionals feel very positive about their patients using complementary therapies. Although your doctor might not know much about the specific therapy you are using they might be able to find out more. You may be able to teach each other. Some health professionals find it helpful to have a letter from the therapist giving details about the complementary therapy.

If they think that it is safe for you to use, most cancer doctors won’t advise you to stop using complementary therapies alongside your conventional cancer treatment.

At the end of this section there is a list of suggested questions for your doctor about complementary and alternative therapies.

Remember that because there is a lack of evidence that they really work and we don't know much about the side effects, your doctor may advise you against using certain types of alternative therapies. 

Your doctor may also advise you not to use particular herbal medicines or dietary supplements because some can possibly interact with conventional cancer treatments.


Giving up conventional treatment to use an alternative therapy

If you are thinking about giving up conventional treatment to try an alternative cancer therapy, it is very important to talk to your doctor first. Of course the final decision rests with you. But your doctor can explain to you that there is evidence that conventional treatments can treat or control your cancer. There is no evidence that alternative therapies can cure or control cancer.

Your doctor will not try to stop you using something that you think might help you. They will explain the possible risks and will always act in your best interests They will also try to make sure that you have considered every possibility available to you.

Even if your doctor doesn’t agree with your decision to start an alternative therapy, they will respect it and acknowledge that using an alternative therapy is important to you. But they may suggest that you should restart your conventional treatment if the alternative therapy has had no effect on your cancer within a set time. It is important to give this some serious thought.

Remember that there is a big difference between a therapy having a physical effect on your cancer and it making you feel better.


Finding more information

The next few pages in this section have information on the safety of using

This section has pages about specific therapies with information about their possible side effects and any precautions you may need to take. 

You can also find information about the cost of the therapies.

Rate this page:
Submit rating


Rated 3 out of 5 based on 17 votes
Rate this page
Rate this page for no comments box
Please enter feedback to continue submitting
Send feedback
Question about cancer? Contact our information nurse team

No Error

Updated: 23 October 2014