What are alternative therapies?

Alternative therapies are different from complementary therapies. They are used instead of conventional medical treatments. They may claim to actively treat or even cure cancer. But there is no scientific proof to support these claims.

No alternative therapies have ever been proven to cure cancer or slow its growth. We do not advocate alternative therapies.

There have been cases where false claims about alternative therapies have led some people to refuse conventional treatments that could have helped them. No reputable alternative therapist will claim to be able to cure cancer.

Why do some people consider alternative therapies?

Some people try alternative therapies because they feel that conventional medical treatment cannot help them or could be harmful.

Cancer treatments and unpleasant side effects can be frightening. However, many people with early cancer can be cured by conventional medical treatments.

If you have been told by your doctors that the cancer cannot be cured, you may find it very hard to accept. However, if a cancer cannot be cured by conventional medical treatment, it is equally true that it won’t be cured with alternative treatment. Some could be very harmful.

Why can alternative therapies sound convincing?

  • Misleading advertising

    Alternative therapies are sometimes very cleverly marketed. This means that when you read about them or are told about them, they sound very effective.

    Therapists may use scientific language to make their claims sound more convincing. But many are based on unproven or disproven theories of how cancer begins or stays in the body.

  • Unreliable evidence

    Claims may be based on the therapy’s results when it is tested on cancer cells in a laboratory. But this can differ greatly from how the therapy will affect a person with cancer.

    Very few suppliers of alternative medicines have carried out scientifically-controlled clinical trials for their products.

  • Individual stories

    Many alternative therapies rely on individuals’ stories or testimonials as evidence that they work. This is called anecdotal evidence and is the least reliable type of evidence.

    It is usually not possible to check whether the effect described is due to the treatment or something else. It is also not possible to check that the person’s story is true, or that the person even existed or had cancer.


If you are considering alternative therapies

If you are considering using alternative therapies, talk to your doctor for advice and support. Alternative therapies can be expensive and some can cause serious side effects.

If you decide to use an alternative therapy, it is important to check it is safe. Always check the credentials of the therapist.

There are many types of alternative therapy. The alternative therapies most well-known by people with cancer are below, but there are many others. If you would like to talk to someone about alternative therapies, you can contact us on 0808 808 00 00.

Amygdalin (Laetrile®, vitamin B17)

Amygdalin is a compound found in bitter almonds, peach stones and apricot stones. When amygdalin is processed by the body, it can be changed to cyanide, a type of poison.

A man-made form of amygdalin is called laetrile. It is also called vitamin B17, although it is not a vitamin.

If you are thinking of taking laetrile, talk to your cancer doctor.

  • Why some people use laetrile
    Many websites that sell laetrile claim it can slow or stop the growth of cancer. They also claim it can poison cancer cells, without damaging normal cells and tissues. But there is no medical evidence to support this.

A review of studies looking at the outcomes for people with cancer taking Laetrile found no evidence that it can control or cure cancer.

  • Possible side effects of laetrile
    Laetrile can have serious side effects. Some people have had cyanide poisoning while taking it and several people have died as a result.

The sale of laetrile has been banned by the European Commission and by the Food and Drugs Administration (FDA) in the USA. If you buy laetrile, there is no way of knowing what it contains, or if it is contaminated with other substances.

Essiac® (Vitaltea®, Flor-essence®)

Essiac is taken as a drink and sold as a nutritional supplement.

It is important to talk to your cancer doctor before you take Essiac during cancer treatment, or with any other medicines.

  • Why some people use Essiac
    Some websites claim Essiac can slow down the growth of cancer, or even cure it. But there is no medical evidence that taking Essiac helps treat cancer or improve your quality of life.
  • Possible side effects of Essiac
    Essiac interferes with an enzyme in the body that regulates hormones and vitamin D. It also has an effect on how the body deals with toxins. This may mean taking Essiac with other treatments could make them less effective or increase side effects.

Metabolic therapy

Metabolic treatments vary from one therapist to another. One of the most well-known is called Gerson therapy. This may include:

  • a diet of raw fruit and vegetables
  • no processed foods or salt
  • vitamins and minerals
  • enzymes or chemicals
  • coffee enemas.

If you have any questions about alternative diets or are thinking of following one, get advice from your doctor, specialist nurse or dietitian.

  • Why some people use metabolic therapies
    Metabolic therapists claim they can treat cancer by removing toxins and strengthening the immune system. No medical evidence has shown that either of these claims are true.

One study compared the results of using a metabolic therapy with chemotherapy. It found that the patients who had the chemotherapy survived three times longer and had better quality of life than those who chose metabolic therapy.

  • Possible side effects of metabolic therapy
    Possible side effects of metabolic or Gerson therapy include nausea, vomiting, stomach cramps, a high temperature and headaches. The high levels of hormones and extracts used can sometimes make people feel unwell. Risks of using coffee enemas include infections. They can also cause serious damage to the large bowel.

Diets that claim to treat cancer

Diets that claim to treat cancer

There are a number of diets, as well as the Gerson diet (above), that claim to treat cancer. Talk to your cancer doctor, nurse or dietitian before cutting out any food group from your diet.


  • Why some people use diets to treat cancer
    Some diets claim to rid the body of toxins. Many of these diets are vegetarian or vegan. They involve eating food that is raw, sugar-free and low in salt. Sometimes vegetable or fruit juices, and high doses of vitamins, minerals or enzymes are used.

Other diets are based on claims that some foods ‘feed’ cancer or affect the pH (acidity) of the body.

There is no medical evidence that these diets can cure cancer or help people with advanced cancer live longer.

  • Possible side effects of diets that claim to treat cancer
    If you choose to follow a diet that cuts out particular types of food, it is important to make sure you aren’t missing out on important nutrients.

Diets that are high in fibre and low in calories and protein are not appropriate for people who have problems maintaining their weight because of cancer or its treatment.

Megavitamin therapy

This type of alternative therapy involves taking very large doses of vitamins. High-dose vitamin C is one of the most common types of megavitamin therapy.

However, there is no evidence that taking large doses of vitamins is helpful in treating cancer.

It is important to tell your cancer doctor before having high doses of vitamin C during, or within a few weeks of, cancer treatment.

  • Possible side effects of megavitamin therapy
    High-dose vitamin C can make many cancer treatment drugs less effective. These include cisplatin, doxorubicin, imatinib and vincristine. It may also interfere with how radiotherapy works.

High-dose vitamin C may also interact with some complementary and alternative therapies.

High-dose vitamin C is not suitable for people who have kidney problems, iron overload (haemachromatosis) or a lack of G6PDH (an enzyme which helps red blood cells work properly).

Getting a second opinion

If your doctor tells you that further treatment will not help to control the cancer, you may understandably find it very hard to accept. In this situation, it can help to have a second medical opinion.

The second doctor may be able to offer you another type of conventional treatment. Or they may confirm what you have already been told.

This may help you to accept that everything that may help has been tried. If you still want to have treatment, you could ask if there are any cancer research trials that might be appropriate for you.

Information about coronavirus

We understand that people are worried about coronavirus (COVID-19). You may have questions about the different vaccines, or you may be worried about how the pandemic will affect your cancer treatment. We have detailed information about coronavirus and cancer treatment here.

Talk to an expert

We know cancer throws a lot your way, and right now, the coronavirus pandemic is making it even tougher. If you're worried about something, and you need to talk to someone, whatever is on your mind, we're here to listen.

To speak to our experts, you can:

Find out more about the Macmillan teams that are here to support you.