Cyproterone (Oral Tablet, Intramuscular)

By lowering the levels of testosterone in the body, cyproterone deprives cancer cells of the hormone they need to keep growing and multiplying.


Belonging to a group of drugs known as steroidal anti-androgens, cyproterone is a medication used in the treatment of advanced stages of prostate cancer. The medication is available as both a tablet (generally in 50 mg strength), and as a long-lasting injectable. When the medication is ingested orally, daily dosages are needed, but as an injectable, only a single dosage per week is necessary. By blocking the actions of the male hormones called androgens, cyproterone deprives cancer cells of the fuel they need to sustain growth and to spread.

While cyproterone does not cure the condition, it is usually effective at slowing down the spread and growth of cancer cells. It also serves to reduce the impact of flare-ups and side effects from other treatments that are being used together with cyproterone. It is also used after surgery, to lessen the discomfort felt from the procedure.

In some unusual cases, cyproterone is also used to control hypersexuality in men who have an uncontrollable need or addiction to sex. When the medication is used for this type of treatment, the prescribing doctor will generally require a patient to sign an agreement relieving him of responsibility for subsequent patient performance.

When patients are prescribed a program of treatment which includes cyproterone, you will be given a Medication Guide which tells you exactly how to take the drug, e.g. with a meal, with water, and at the same time each day for best results. This guide should be read thoroughly by patients and the instructions contained in it should be closely adhered to, so as to avoid any problems with the medication.

Condition Treated

  • Advanced prostate cancer

Type of Medicine

  • Steroidal anti-androgens

Side Effects

There are certain side effects which appear in some patients in addition to the desirable effects achieved by the medication. If any of the side effects listed below occur after you take cyproterone, you should consult with your doctor and convey to him/her the specific type of side effect you are experiencing, as well as the severity of the discomfort.

Some of the most common side effects which appear in patients taking cyproterone are:

• Much lower sperm count
• Much lower interest in sex
• inability to achieve a state of erection
• significantly less liquid during ejaculation
• restlessness or increased agitation
• weight gains which are attributable to fluid retention
• a persistent down mood
• unusual swelling and tenderness in the area of the breasts
• more or less constant tiredness.

Some of the less common symptoms which are manifested by patients taking cyproterone include the following:

• rashes at various locations around the body
• release of whitish fluid around the nipples
• lumps which can be felt in the area of the breasts
• malignant liver tumors
• significantly weaker bones, and even osteoporosis
• extremely dry or scaly skin
• profuse sweating
• flushes of warmth at odd times
• thrombosis
• heart attack
• stroke
• swelling in the ankles or in the lower legs
• less growth of hair on the legs, arms, and back
• more growth of hair on the scalp
• general reduction in the amount of body hair
• difficulty breathing especially with shortness of breath
• liver problems, which in the most severe scenarios can be fatal, although the rare cases reported were all associated with very high dosage treatment.


Cyproterone can be administered via an intramuscular route, i.e. injected directly into the muscle, and when this approach is used, the standard adult dosage would be 300 mg injected into the muscle, once weekly.

When cyproterone is ingested orally, a standard dosage is between 200 mg and 300 mg, which would be either four or six tablets. These dosages should be divided up and spaced out through the day, so that no more than two tablets are taken at any one time. It is best to take the tablets directly after a meal, and at the same time every day so it helps you to remember to take your medication. Do not double up on doses if you happen to forget one of your normal dosage times – just wait until the next time and take that dosage. For those patients who have had testicles removed, lower dosages are commonly indicated, because less testosterone is being produced.

Your doctor may recommend a somewhat different dosage schedule, due to other medications you may be taking, your personal medical condition at the moment, and even your height and weight. Whatever your doctor recommends, should be carefully followed.


There are some medications which are known to interact with cyproterone, and when this happens either the effectiveness of cyproterone may be reduced, or the effectiveness of the other medications may be reduced. In order to avoid situations like this, it is advisable to prepare a list of all the medications you are currently taking, including vitamins, herbal supplements, over-the-counter drugs, and other prescription medications, as well as all of the dosages of each of these. Your doctor will review this list and make sure that there are no negative interactions between your current medications and cyproterone before recommending treatment with this drug.

Although this is not a complete list, the drugs below are known to interact with cyproterone to some extent:

• cholesterol-lowering medications, for instance, those known as statins
• medications which treat HIV, such as ritonavir
• tuberculosis treatment medications, for example, rifampicin
• epilepsy medications such as phenytoin
• antifungal medications including clotrimazole, ketoconazole, and itraconazole
• Hypericum perforatum, which is more commonly known as St. John's wort, and is a popular herbal remedy
• antidiabetic medications and insulin.


There are a number of precautions and warnings that should be observed by patients in a program of treatment which includes cyproterone. Some of these are serious enough that all patients taking the medication should be observed for any noticeable reactions, and some of the warnings are better categorized as disqualifications for patients taking the medication. Cyproterone should be used with considerable caution by patients with any of the following medical conditions:

• patients having liver disease or any history of liver problems
• people who have either type of diabetes
• patients who have suffered heart attacks or strokes in the past, or who have a history of heart problems
• patients who have sickle-cell anemia
• those people with a significant history of depression
• anyone who has a history of blood clots.

Cyproterone should not be used by people who have the following medical conditions:

• people who suffer from a wasting disease that causes the gradual loss of muscle and/or weight
• people who are hypersensitive to cyproterone acetate or any of the ingredients used to make it
• people who have suffered thrombosis or embolism in their past
• people under 18 years of old, whose bones and/or testes may not yet be mature
• women who are currently pregnant or think they may become pregnant
• people who have been diagnosed with tumors of the tissue layer between skull and brain, commonly known as meningiomas
• women who are breastfeeding
• people who have had liver disease or have had tumors on the liver in their past
• people with any form of cancer other than prostate cancer.

In addition to the exclusions and warnings listed above, there are some other alerts or precautions that patients using cyproterone should observe:

• if taking cyproterone in its injectable form, the injection site should be watched for any signs of irritation, including inflammation, redness, rash, or other manifestations
• you should either discontinue drinking alcohol while on this medication or drastically reduce your intake, because alcohol interferes with the effectiveness of cyproterone
• this medication can make you feel very weak or tired, and if you experience this kind of reaction, you need to avoid operating any kind of machinery or driving a motor vehicle
• be sure to make your best effort at keeping all doctor appointments while being treated with cyproterone, because your blood levels will probably be checked frequently in order to determine how effective the medication is, and your doctor will also probably need to ensure that your adrenal glands are not being negatively impacted by the drug
• after taking cyproterone for several weeks, your sperm count will drop significantly and you will probably be unable to have a pregnancy with your partner. The infertility caused by cyproterone is temporary, and in most cases, when treatment of the drug ceases, sperm count build back up to an acceptable and effective level. For any questions in this general area, you should consult your doctor.

Cyproterone sometimes has an impact on liver function and/or the function of the body's adrenal glands. This will be an issue that your doctor discusses with you prior to arranging any kind of treatment program with cyproterone, but it will be up to you to keep a lookout for conditions which signal that either of these two body functions have been negatively affected:

• if you begin to feel excessively fatigued or tired after starting up a program with cyproterone
• you start losing weight because your appetite is much less
• diarrhea develops and persists over the course of days or weeks
• you feel an unexplained irritability or depression that you can’t suppress
• your skin becomes yellowish in color at certain locations on the body, or you may see a yellowish tinge around the whites of the eyes
• you develop stomach pain or discomfort that seems to last for hours.


Cyproterone should never be stored in a location where pets or curious children may be able to reach the medication, and for this reason, storing in a very high location somewhere in the home is advisable. The room where it is kept should be free of temperature extremes, and for the most part, should be near room temperature. Excessive humidity is bad for the medication, and will likely reduce its effectiveness, so storing it in the bathroom medicine cabinet is not advisable.

No direct lighting should shine on the location where cyproterone is stored, and it should not be kept in a weekly pill reminder, because very few of these containers have locking lids on them. That makes it quite possible for children to access the container, and possibly ingest some of the medications being stored. If you suspect that a child has ingested one or more cyproterone tablets, you should contact the Poison Control Center and ask for instructions.

When you need to discard unused medication, you should not throw it in the garbage, flush it down the toilet, or put it in the sink. Instead, use a disposal method approved by the FDA on its website for the Safe Disposal of Medicines. Your area may also have a medication take-back program, so you can just drop off any unused cyproterone, and let the professionals handle it.


Cyproterone is a medication which is commonly used to reduce the level of testosterone in the body, generally as a strategy for starving out cancer cells which require that hormone for growth and reproduction. For that reason, cyproterone is used to treat prostate cancer, or in some cases to treat men who have a hyperactive sex drive, and desire to have it brought under control.

It is made available in tablet form, usually in 50 mg dosages, and can be easily ingested with water after a meal. It is also available in an injectable form, which would be administered once per week, rather than the daily regimen necessary for tablets. There can be some minor side effects as well as some major ones, and your doctor will want to monitor your condition frequently to determine if any of these are present. It will also be necessary to have frequent bloodwork done while you are being treated with cyproterone, so that it can be determined if the medication is being effective or not.

This medication cannot cure prostate cancer, but by lowering the level of testosterone, it can delay the spread and growth of cancer cells, and extend the life expectancy of a patient who has contracted the disease.