Flutamide is a type of hormone therapy. It is a treatment for advanced prostate cancer.

How flutamide works

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

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

How 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. 

Taking your tablets

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.

When you have flutamide

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

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. 

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 have blood tests before and during your treatment. They check your levels of blood cells and other substances in the blood. They also check how well your liver and kidneys are working.

Side effects

How often and how severe the side effects are 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 and the possible treatments for men and women. 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

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

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, such as if you've had 4 or more loose watery poos (stools) in 24 hours. Or if you can't drink to replace the lost fluid. Or if it carries on for more than 3 days.

Your doctor may give you anti diarrhoea medicine to take home with you after treatment. Eat less fibre, avoid raw fruits, fruit juice, cereals and vegetables, and drink plenty to replace the fluid lost.

Feeling or being sick

Feeling or being sick is usually well controlled with anti sickness medicines. Avoiding fatty or fried foods, eating small meals and snacks, drinking plenty of water, and relaxation techniques can all 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 treating 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
  • liver changes
  • difficulty sleeping (insomnia)
  • increased appetite
  • inflammation of the liver (hepatitis)

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:

  • herpes zoster virus
  • 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
  • heart changes such as high blood pressure or fluid build up (oedema)
  • lung changes
  • non-specific abdominal disorders, constipation, ulcer-like pain, dyspepsia, colitis, upset stomach
  • heartburn
  • skin changes such as a rash
  • change in hair growth pattern and loss of hair (head)
  • muscle cramps
  • feeling thirsty

Coping with side effects

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

What else do I need to know?

Other medicines, foods and drink

Cancer drugs can interact with some other medicines and herbal products. Tell your doctor or pharmacist about any medicines you are taking. This includes vitamins, herbal supplements and over the counter remedies.

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 father a child 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

Always tell other doctors, nurses, pharmacists or dentists that you’re having this treatment if you need treatment for anything else, including teeth problems.


You should not drink large amounts of alcohol when you are taking flutamide.


Speak to the team looking after you if you have an intolerance to some sugars (lactose intolerance).

More information about this treatment

For further information about this treatment go to the electronic Medicines Compendium (eMC) website.

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

This page is due for review. We will update this as soon as possible.

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