What is cyproterone acetate (Cyprostat®)?

Cyproterone acetate (cyproterone or Cyprostat®) is a hormonal therapy drug used to treat prostate cancer. It can be given alone or with other types of treatment. It is best to read this information with our information about prostate cancer

Your doctor will talk to you about this treatment and its possible side effects before you agree (consent) to have treatment.

How cyproterone works

Hormones are chemicals that our bodies make. Hormones act as messengers and help control how cells and organs work. Hormonal therapies are drugs that change the way hormones are made or how they work in the body.

Most prostate cancers need the hormone testosterone to grow. Almost all testosterone in men is made by the testicles.

Cyproterone reduces the amount of testosterone made by the body and also blocks it from reaching the cancer cells.

Cyproterone can be given:

  • on its own, with other hormonal therapies.
  • for a few weeks when taking hormonal drugs called LHRH agonists to prevent any symptoms getting worse because of a temporary rise in testosterone (called tumour flare).
  • to reduce hot flushes caused by other prostate hormonal treatments.

Your doctor or nurse will explain how long you should take it for.

Taking cyproterone tablets

Cyproterone comes as tablets you can take at home. You may have cyproterone on its own, or with other drugs. Your nurse or doctor will talk to you about your treatment plan. They may advise you to avoid drinking alcohol while you are taking this treatment. This is because drinking alcohol makes cyproterone less effective.

Always take the tablets exactly as explained. This is important to make sure they work as well as possible for you. Make sure you:

  • take the tablets after meals.
  • swallow them whole with a glass of water.

If you forget to take the tablets, you should wait and take your normal dose the following day. Do not take a double dose to make up for the one you missed.

Other things to remember about your tablets:

  • Keep them in the original package and at room temperature, away from heat and direct sunlight.
  • Keep them safe and out of sight and reach of children.
  • Get a new prescription before you run out of tablets, and make sure you have plenty for holidays.
  • If your treatment is stopped, return any unused tablets to the pharmacist.

Your nurse or pharmacist may also give you other medicines to take home. Take all your medicines exactly as they have been explained to you. Do not stop taking any of your medicines unless your doctor tells you to.

About side effects

We explain the most common side effects of this treatment here. We also include some less common side effects.

You may get some of the side effects we mention, but you are unlikely to get all of them. If you are also having treatment with other cancer drugs, you may have some side effects that we have not listed here.

You will see a doctor, nurse or pharmacist regularly while you are having this treatment. Always tell them about any side effects you have. They can give you drugs to help control most side effects. They can also offer advice to help you cope.

Most side effects can be managed. But sometimes side effects are harder to control. It is important not to stop taking hormonal therapy without telling your doctor. If side effects cannot be managed, your doctor may suggest you take a different type of hormonal therapy.

Serious and life-threatening side effects

Some cancer treatments can cause severe side effects. Rarely, these may be life-threatening. Your cancer doctor or nurse can explain the risk of these side effects to you.

Contact the hospital

Your nurse will give you telephone numbers for the hospital. If you feel unwell or need advice, you can call them at any time of the day or night. Save these numbers in your phone or keep them somewhere safe.

More information

We cannot list every side effect for this treatment. There are some rare side effects that are not listed. You can visit the electronic Medicines Compendium (eMC) for more detailed information.

Common side effects

Hot flushes and sweats

Hot flushes are a common side effect of this treatment. During a flush, your neck and face may feel warm and look red. Flushes may last from a few seconds up to 10 minutes. You may have sweats and then feel cold and clammy. Some people feel anxious or irritable during a hot flush.

There are things you can do to try to reduce flushes:

  • Wear clothes made from natural fabrics, such as cotton.
  • Wear layers of clothes that you can remove if you feel hot.
  • Use cotton bed sheets and have layers of bedding that you can remove if you feel hot.
  • Keep room temperatures cool or use a fan.
  • Have cold drinks rather than hot ones. Try to avoid drinks with caffeine in them.

You may have fewer hot flushes and sweats as your body adjusts to hormonal treatment. Or your doctor can prescribe drugs to help. Flushes and sweats usually stop a few months after treatment finishes, but some people continue to have them.

You can read more about coping with hot flushes.

Sexual effects

Most men lose their sex drive and have erection problems during hormonal therapy. Things often return to normal after you stop taking the drug. But some men continue to have problems after treatment is over. Your doctor can prescribe treatments to help with erection problems. But these treatments will not increase your sex drive.

Weight gain

You may put on weight, or your ankles and legs may become swollen. This is due to fluid building up. Tell your doctor or nurse if this happens. The swelling will get better after your treatment ends.

Mood changes

You may have some mood changes during this treatment. You may feel low or depressed. Let your doctor or nurse know if you notice any changes.

Breast swelling or tenderness

This treatment may cause swelling and tenderness of your breast tissue. This is called gynaecomastia. Your doctor can give you advice on preventing and treating this.

Tiredness

Feeling tired is a common side effect. Try to pace yourself and plan your day so you have time to rest. Gentle exercise, like short walks, can give you more energy. If you feel sleepy, do not drive or operate machinery.

Breathlessness

You may feel slightly short of breath while you are taking this treatment. Tell your doctor or nurse if this happens. This should stop when the treatment finishes.

Effects on the liver

Treatment may affect how your liver works. This is usually mild. You will have blood tests to check how well your liver is working. Tell your doctor if you notice any yellowing of your skin or eyes.

Very rarely, this treatment may increase the risk of developing a new cancer in the liver.

Raised blood sugar levels

This treatment can raise your blood sugar levels. If you have a raised blood sugar level, you may:

  • feel thirsty
  • need to pass urine (pee) more often
  • feel tired.

Tell your doctor or nurse if you have these symptoms.

If you have diabetes, your blood sugar levels may be higher than usual. Your doctor will talk to you about how to manage this. You may need to change your insulin or tablet dose.

Less common side effects of cyproterone

Anaemia (low number of red blood cells)

This treatment can reduce the number of red blood cells in your blood. These cells carry oxygen around the body. If the number of red blood cells is low, you may be tired and breathless. Tell your doctor or nurse if you feel like this. If you are very anaemic, you may need a drip to give you extra red blood cells. This is called a blood transfusion.

Skin changes

This treatment may affect your skin. It may cause a rash, which might be itchy. Your doctor or nurse can tell you what to expect. If your skin feels dry, try using an unperfumed moisturising cream every day.

Always tell your doctor or nurse about any changes to your skin. They can give you advice and may prescribe creams or medicines to help. Skin changes usually improve when treatment finishes.

Hair changes

There may be changes to how your hair grows and it may also be drier. For example, the hair on your head may thicken or you may lose some body hair.

Allergic reaction

Some people have an allergic reaction while having this treatment. Signs of a reaction can include:

  • feeling hot or flushed
  • a skin rash
  • itching
  • shivering
  • feeling dizzy
  • a headache
  • feeling breathless.
  • pain in your back, tummy or chest.

If you feel unwell or have any of these signs, tell a doctor or nurse straight away. Do not take any more of this treatment until you have spoken to them.

Meningioma

When this treatment is taken for a long time, there is a very rare risk of developing a type of brain tumour called a meningioma. Your cancer doctor or nurse can give you more information.

Other information about cyproterone

Blood clot risk

Cancer and some cancer treatments can increase the risk of a blood clot. Symptoms of a blood clot include:

  • pain, redness or swelling in a leg or arm
  • breathlessness
  • chest pain.

If you have any of these symptoms, contact a doctor straight away.

A blood clot is serious, but can be treated with drugs that thin the blood. Your doctor or nurse can give you more information.

Problems with lactose

These tablets contain a type of sugar called lactose. If you have been told by a doctor that you cannot digest some sugars or are lactose intolerant, talk to your doctor before taking this drug.

Other medicines

Some medicines can affect how this treatment works or be harmful when you are having it. Always tell your cancer doctor about any drugs you are taking or planning to take, such as:

  • medicines you have been prescribed
  • medicines you buy in a shop or chemist
  • vitamins, herbal drugs and complementary therapies.

Tell other doctors, pharmacists or dentists who prescribe or give you medicines that you are having this cancer treatment.

You can visit the electronic Medicines Compendium (eMC) for more detailed information about your treatment.

Fertility

Some drugs can affect whether you can make someone pregnant.

There may be ways to preserve your fertility. If you are worried about this, it is important to talk with your doctor before you start treatment.

Contraception

Your doctor will advise you not to make someone pregnant while having this treatment. The drug may harm the developing baby. It is important to use effective contraception during your treatment.

Medical and dental treatment

If you need medical treatment for any reason other than cancer, always tell the doctors and nurses that you are having cancer treatment. Give them the contact details for your cancer doctor so they can ask for advice.

If you think you need dental treatment, talk to your cancer doctor or nurse. Always tell your dentist you are having cancer treatment.