Cyproterone acetate (Cyprostat)

Cyproterone is a type of hormone therapy and is also known by its brand name Cyprostat. You might have it is as a treatment for prostate cancer:

  • that has spread to other parts of the body (advanced)
  • if you can’t have surgery or other medicine to treat your cancer
  • to treat hot flushes

How it works

Prostate cancer cells depend on the hormone testosterone in order to grow. Cyproterone lowers levels of testosterone in the body and also blocks testosterone from reaching the cancer cells. It slows or stops the growth of prostate cancer. 

How you have it

You take cyproterone acetate either on its own, or with another type of drug for prostate cancer called a luteinising hormone (LH) blocker. 

You take cyproterone acetate as a tablet 1 to 3 times a day. This depends on why you are taking it. Take it with a drink after meals. Try to take it at evenly spaced times during the day.

When you stop taking cyproterone you need to reduce the amount (dose) gradually. Your doctor will tell you exactly how to do this.

Taking your tablets or capsules

You must take tablets and capsules 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 have missed a dose.

When you have cyproterone acetate

You take cyprotene cyproterone acetate for as long as it is working, and the side effects aren’t too bad.

Tumour flare reaction

You might have cyproterone acetate with a luteinising hormone blocker to stop a flare reaction. When you first start taking LH blockers you make more testosterone for the first few days or weeks, which increases the symptoms of the prostate cancer. Cyproterone acetate helps to reduce any cancer symptoms caused by this temporary increase in testosterone.,

You take cyprotene cyproterone acetate for a few days before starting the luteinising hormone 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:

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. 

Erection problems

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.

Reduced sperm and ejaculate

Talk to the team looking after you about this before starting treatment.

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:

  • breast tenderness and swelling
  • tiredness and weakness (fatigue)
  • depression or mood changes
  • hot flushes or sweats
  • swelling in parts of the body (fluid build up)
  • weight changes
  • liver changes (you will have regular blood tests to check for this)
  • shortness of breath

Rare side effects

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

  • skin rash
  • an allergic reaction that can cause a rash, shortness of breath, redness or swelling of the face and dizziness
  • a second cancer called liver cancer

Other side effects

There isn't enough information to work out how often these side effects might happen. You might have one or more of them. They include:

  • blood clots that can be life threatening; signs are pain, redness and swelling where the clot is. Feeling breathless can be a sign of a blood clot in the lung. Contact your advice line or doctor straight away if you have any of these symptoms
  • weakening of the bones (osteoporosis)
  • breathlessness and looking pale (due to low number of red blood cells)
  • dryness of the skin, scalp and hair
  • risk of developing a brain tumour (meningioma)

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.


Drinking excessive amounts of alcohol can reduce the effect of this drug. 

Lactose intolerance

This drug contains lactose (milk sugar). If you have an intolerance to lactose, contact your doctor before taking this medicine.

Treatment for other conditions

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

If you have diabetes

This drug may affect your blood sugar levels if you have diabetes. You need to check your blood sugar more often when you are having this treatment.


It is important not to father a child while you are having treatment with this drug and for a few months afterwards. This drug may harm a baby developing in the womb. Talk to your doctor or nurse about effective contraception before starting treatment. 


This drug can cause infertility in some men, but it is usually temporary. Fertility can return some months after treatment ends but the time it takes can vary. The effects of long term treatment on fertility is not known.

Talk to your doctor before starting treatment if you think you may want to have a baby in the future.

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.

Related links