Hormone drug: Cyproterone acetate (Brand name: Cyprostat®)
The information on this page comes from our Tool Kit fact sheet on Cyproterone. To order your own tailored copy of the Tool Kit, visit our publications page. You can also download and print a PDF version of this fact sheet.
This page is for men who are about to start, or are already taking, cyproterone to control their prostate cancer. It explains how the drug is taken, why it is used and what side effects it may cause. Read our Hormone therapy pages for more information about how hormone therapy is used to treat prostate cancer. We hope these pages will help you to make decisions about your treatment. They should be used together with the information that comes with your medicine and the advice of your specialist team or pharmacist.
- What is cyproterone acetate?
- How do I take cyproterone acetate?
- What happens if I miss an injection?
- What are the side effects?
- More information
What is cyproterone acetate?
Cyproterone acetate is a form of hormone therapy called an anti-androgen. It comes as 50mg and 100mg tablets. One brand name for this drug is cyprostat ®.
Cyproterone acetate and all anti-androgens work by stopping testosterone from reaching the cancer cells. Without testosterone the prostate cancer cells are not able to grow. Cyproterone acetate will not cure prostate cancer but it can keep the cancer under control.
How do I take cyproterone?
You should try and take your cyproterone acetate tablets after meals. The amount you take will depend on why you need the drug. There are three main reasons for taking cyproterone acetate.
Flare
If you are about to start treatment with another type of hormone therapy called an LHRH agonist, you may take cyproterone acetate. This is to prevent the body’s normal response to the first injection of this drug, which is to produce testosterone. This temporary rise in testosterone could cause the cancer to grow more quickly for a short time. This is known as a flare. An anti-androgen tablet like cyproterone acetate can help to prevent this flare from happening.
To prevent flare, you may take a total of 300mg of cyproterone acetate each day for up to three weeks after your first LHRH agonist injection. If you have problems with side effects after taking cyproterone acetate, this dose may be reduced to 200mg a day. You will take the tablets two or three times a day after meals.
Treatment of prostate cancer
Occasionally some men may take cyproterone acetate on its own to slow down the growth of the cancer. Other men take cyproterone acetate together with an LHRH agonist. This is often because an LHRH agonist on its own or surgery to remove the testicles (orchidectomy) is no longer controlling the cancer. You will need to take a total of between 200mg and 300mg each day, divided into two or three doses after meals.
Treatment of hot flushes
Cyproterone acetate may be used to treat hot flushes caused by other hormone treatments (LHRH agonists or orchidectomy). To start with you may take 50mg once a day, which can be increased to 100mg or 150mg if needed. Some specialist teams may do things differently.
What are the side effects?
Like all drugs, cyproterone acetate can cause side effects in some men. The risk of side effects may vary depending on the dose you are taking. We have listed the most common ones 1 here but you should tell your specialist team if you notice any other changes while you are having treatment.
Some men get very few side effects and others get more. Many side effects will only last for as long as you are taking the drug. However, if you take cyproterone acetate for a long period of time, it may take several months after you finish treatment for the side effects to stop.
You can find out more about the side effects of hormone therapy and ways that you can manage them by reading our booklet Living with hormone therapy: A guide for men with prostate cancer. |
Before you take cyproterone acetate, you should tell your doctor if:
- You have liver problems. Higher doses of cyproterone acetate (200mg to 300mg) can affect how well your liver works after several months of treatment. You will have regular blood tests to check your liver for as long as you are taking the drug.
- You are a heavy drinker. You may not be able to take cyproterone acetate, as alcohol may stop it from working properly. 1
- You have any problems with your blood, heart or circulation
- You have a history of blood clots, strokes or heart attacks, sickle-cell anaemia or severe diabetes that affects your blood circulation. This is because cyproterone acetate has caused blood clots in some men.
You should also let your specialist team know if you are taking any prescription or over-the-counter medicines.
Loss of sex drive
Cyproterone acetate may cause you to lose your sex drive (libido) for as long as you are taking the drug. After you have been taking cyproterone acetate for a few months your sperm count is likely to drop. You will probably not be able to make anyone pregnant but it is important to remember that this does not happen straight away. You should still use contraception if you want to avoid having children. Cyproterone acetate may cause some of your sperm to become abnormal in shape. Some experts believe that abnormal sperm might possibly lead to babies being born with abnormalities, but we do not know this for sure1. Speak to your specialist team if you are thinking of having children.
Weight changes
You may either put on or lose weight if you take cyproterone acetate for a long period of time.
Anxiety and depression
Cyproterone acetate affects your hormone levels and this can cause mood swings. If you have depression, cyproterone acetate can make your symptoms worse. Your specialist team can offer support and advice.
Breast swelling and tenderness
Some men may experience breast swelling (gynaecomastia) and tenderness in the breast area. This can affect one or both breasts and can range from mild sensitivity to ongoing pain. The amount of swelling can also vary from a small amount to a more noticeable enlarged area.
Tiredness
You may feel tired when you start to take cyproterone acetate. You may find that your tiredness improves over time but many men find that regular exercise gives them more energy and helps them to cope with treatment. 2
| Reporting unusual side effects: The Yellow Card Scheme If you think you are experiencing a side effect from your medication that is not mentioned in the information leaflet that comes with it, then you can report it using the Yellow Card Scheme. This is run by the Medicines and Healthcare products Regulatory Agency (MHRA). They will investigate and if they find a problem with a medication then the MHRA will take action to protect the public. There are three ways you can report a side effect: |
How long will I need to take cyproterone?
The length of time you take cyproterone acetate for depends on why you are taking it and how well it is working. Due to its effects on the liver, it is unlikely that you will take cyproterone acetate for more than a few months. Speak to your specialist team or call our confidential Helpline for information on other treatments that can be used if hormone therapy is no longer controlling the cancer.
More information
To find out more about hormone therapy you can read:
- The hormone therapy pages. They give an overview of different types of hormone therapy.
- The booklet Living with hormone therapy: A guide for men with prostate cancer. This includes more detailed information on side effects and ways to manage them.
Reviewed by:
- Mr Simon F Brewster, Consultant Urological Surgeon, Churchill Hospital, Oxford and Honorary Senior Clinical Lecturer in Surgery, University of Oxford
- Bruce Turner, Uro-oncology Nurse Practioner, Homerton University Hospital NHS Foundation Trust and Whipps Cross University Hospital NHS Trust, London
- Deborah Victor, Urology Cancer Clinical Nurse Specialist, Royal Cornwall Hospitals NHS Trust, Truro
- Cathryn Woodward, Consultant Clinical Oncologist, Addenbrooke’s Hospital, Cambridge
- The Prostate Cancer Charity Information Volunteers
- The Prostate Cancer Charity Support & Information Specialist Nurses/li>
Written and edited by:
The Prostate Cancer Charity Information Team
References used in the production of this page.
1. Summary of Product Characteristics: Cyprostat 50/100mg. Bayer HealthCare September 2009. Available at: http://emc.medicines.org.uk
2. Segal RJ, Reid RD, Courneya KS et al. Resistance training in men receiving androgen deprivation therapy for prostate cancer. Journal of Clinical Oncology 2003; 21: 1653-1659.