Flutamide is a type of hormone therapy Open a glossary item. It is a treatment for advanced (metastatic) prostate cancer.

You pronounce flutamide as floo-ta-mide.

How does flutamide work?

Prostate cancer needs the male hormone testosterone to grow. Testosterone is also called an androgen Open a glossary item

Flutamide is a type of hormone drug called an anti androgen Open a glossary item. It stops testosterone from reaching the cancer cells. This can slow the growth of your cancer and may shrink it. 

How do you have flutamide?

Flutamide is a tablet. You take it 3 times a day.

You should swallow the tablet whole with a glass of water. 

Take your flutamide tablets after food.

You must take tablets according to the instructions your doctor or pharmacist gives you.

You should take the right dose, not more or less.

Talk to your healthcare team before you stop taking a cancer drug, or if you miss a dose.

How often do you have flutamide?

You might have flutamide before or during other hormone treatments called luteinising hormone (LH) blockers Open a glossary item (such as goserelin, leuprorelin and triptorelin). LH blockers work by lowering the level of testosterone (the male sex hormone). It stops the release of luteinising hormone from the pituitary gland. Open a glossary item

You need to take flutamide before you start some other types of hormone treatment because they can take a few weeks to lower your testosterone. During this time they can make your symptoms worse. This is called tumour flare Open a glossary item

If you are having flutamide to stop a flare reaction, you take it for a few days before starting the LH blocker, and stay on it for about 4 to 6 weeks. 


You nay have blood tests before and during treatment.

What are the side effects of flutamide?

Side effects can vary from person to person. They also depend on what other treatment you are having. 

When to contact your team

Your doctor, nurse, or pharmacist will go through the possible side effects. They will monitor you closely during treatment and check how you are at your appointments. Contact your advice line as soon as possible if:

  • you have severe side effects 

  • your side effects aren’t getting any better

  • your side effects are getting worse

Early treatment can help manage side effects better.

We haven't listed all the side effects here. Remember it is very unlikely that you will have all of these side effects, but you might have some of them at the same time.

Common side effects

These side effects happen in more than 10 in 100 people (more than 10%). You might have one or more of them. They include:

Hot flushes 

We have some tips for coping with hot flushes in men. This information also includes some of the possible treatments. Talk to your doctor if your hot flushes are hard to cope with. They might be able to prescribe you some medicines.

Loss of interest in sex (libido)

Talk to your doctor if you have this. You might be able to have some treatments to help with low libido. 

Unable to get an erection (impotency)

You might have problems getting an erection (impotence). Talk to your doctor or nurse if you have problems getting an erection. There are treatments that can help, such as medicines, vacuum pumps and injections or pellets. Your doctor or nurse can refer you to a specialist in this area.

Breast swelling (Gynaecomastia)

Talk to the team looking after you about this. You might also have breast pain or some milk leaking from the breasts.


Contact your advice line if you have diarrhoea. For example, in one day you have 2 or more loose bowel movements than usual. If you have a stoma, you might have more output than normal. Your doctor may give you anti diarrhoea medicine to take home with you after treatment.

Try to eat small meals and snacks regularly. It’s best to try to have a healthy balanced diet if you can. You don’t necessarily need to stop eating foods that contain fibre. But if your diet is normally very high in fibre, it might help to cut back on high fibre foods such as beans, nuts, seeds, dried fruit, bran and raw vegetables. 

Drink plenty to try and replace the fluid lost. Aim for 8 to 10 glasses per day.

Feeling or being sick

Feeling or being sick is usually well controlled with anti sickness medicines. It might help to avoid fatty or fried foods, eat small meals and snacks and take regular sips of water. Relaxation techniques might also help.

It is important to take anti sickness medicines as prescribed even if you don’t feel sick. It is easier to prevent sickness rather than treat it once it has started.

Occasional side effects

These side effects happen in between 1 and 10 out of every 100 people (between 1 and 10%). You might have one or more of them. They include:

  • tiredness and weakness (fatigue)
  • drowsiness
  • temporary changes to how the liver works
  • difficulty sleeping (insomnia)
  • increased appetite
  • inflammation of the liver (hepatitis) causing itching, dark urine, yellowing of the skin or whites of the eyes

Rare side effects

This side effects happens in fewer than 1 in 100 people (fewer than 1%). You might have one or more of them. They include:

  • shingles (herpes zoster)
  • breathlessness and looking pale
  • bruising, bleeding gums or nosebleeds
  • low levels of white blood cells
  • lupus-like syndrome
  • loss of appetite
  • anxiety and depression
  • dizziness and headache
  • blurred vision
  • changes to how well the heart works
  • chest pain
  • high blood pressure
  • inflammation of the lungs
  • skin changes such as a rash, itching and hives
  • constipation
  • ulcer-like pain such as a burning or gnawing feeling in the tummy
  • upset stomach
  • swelling especially of the arms, legs and genitals
  • inflammation of the bowel
  • heartburn and indigestion
  • changes to how well the hair grows and loss of hair
  • muscle cramps and pain
  • joint pain
  • feeling thirsty
  • an increase of testosterone, creatinine and urea in the blood
  • thinning of the bones (osteoporosis)
  • problems passing urine, pain when passing urine and changes to the colour of the urine
  • nerve problems

Coping with side effects

We have more information about side effects and tips on how to cope with them.

What else do you need to know?

Other medicines, foods and drink

Cancer drugs can interact with medicines, herbal products, and some food and drinks. We are unable to list all the possible interactions that may happen. An example is grapefruit or grapefruit juice which can increase the side effects of certain drugs.

Tell your healthcare team about any medicines you are taking. This includes vitamins, herbal supplements and over the counter remedies. Also let them know about any other medical conditions or allergies you may have.

Pregnancy and contraception

This treatment may harm a baby. So it is important not to father a child while you are having treatment and for a few months afterwards. Talk to your doctor or nurse about effective contraception before starting treatment.

Loss of fertility

You may not be able to get someone pregnant after treatment with this drug. Talk to your doctor before starting treatment if you think you want to have a baby in the future. You may be able to store sperm before starting treatment.

Treatment for other conditions

If you are having tests or treatment for anything else, always mention your cancer treatment. For example, if you are visiting your dentist.

More information about this treatment

For further information about this treatment and possible side effects go to the electronic Medicines Compendium (eMC) website. You can find the patient information leaflet on this website.

You can report any side effect you have to the Medicines Health and Regulatory Authority (MHRA) as part of their Yellow Card Scheme.

Related links