Cyproterone belongs to a group of medications known as steroidal antiandrogens. It is used to treat advanced prostate cancer. Antiandrogens such as cyproterone block the effect of the hormone called testosterone. This causes a reduction in the production of testosterone in the testicles, which prostate cancer cells require for growth.

This medication may be available under multiple brand names and/or in several different forms. Any specific brand name of this medication may not be available in all of the forms or approved for all of the conditions discussed here. As well, some forms of this medication may not be used for all of the conditions discussed here.

Your doctor may have suggested this medication for conditions other than those listed in these drug information articles. If you have not discussed this with your doctor or are not sure why you are taking this medication, speak to your doctor. Do not stop taking this medication without consulting your doctor.

Do not give this medication to anyone else, even if they have the same symptoms as you do. It can be harmful for people to take this medication if their doctor has not prescribed it.

Cyproterone is available as an oral (by mouth) tablet and as a long-acting injectable. The recommended dose for cyproterone tablets is 200 mg to 300 mg (4 to 6 tablets) daily, divided into 2 to 3 doses and taken after meals. For men who have had an orchiectomy (removal of testicles), a lower dose of 100 mg to 200 mg daily in divided doses is recommended. 

The recommended dose for the long-acting form of cyproterone (Androcur® Depot) is 300 mg injected into a muscle once a week. For men who have had an orchiectomy, the recommended dose is 300 mg injected every 2 weeks.

Many things can affect the dose of medication that a person needs, such as body weight, other medical conditions, and other medications. If your doctor has recommended a dose different from the ones listed here, do not change the way you are using the medication without consulting your doctor.

Cyproterone can cause weakness and tiredness when you first start to take it. After about the third month, your body will become accustomed to the medication and this effect should be lessened.

It is important to take this medication exactly as prescribed by your doctor. If you are taking cyproterone tablets and you miss a dose, skip the missed dose and continue with your regular dosing schedule. Do not take a double dose to make up for a missed one. If you are not sure what to do after missing a dose, contact your doctor or pharmacist for advice.

If you are receiving the injectable form of cyproterone, and you miss an appointment to receive this medication, contact your doctor as soon as possible to reschedule your appointment.

Alcohol intake should be limited while taking cyproterone because it may reduce the effectiveness of the medication.

Store the medication at room temperature, protect it from light and moisture, and keep it out of the reach of children.

Each white to faintly yellowish, round, flat-sided, bevelled-edged tablet, imprinted one side "BV" in a regular hexagon, other side scored, contains cyproterone acetate 50 mg. Nonmedicinal ingredients: colloidal anhydrous silicica, lactose monohydrate, magnesium stearate, maize starch, and povidone 25.

Do not take this medication if you:

• are allergic or sensitive to cyproterone or any ingredients of this medication
• have active liver disease or reduced liver function
• have or have a history of liver tumours
• have or have a history of a benign brain tumour (meningioma)
• have severe, long-term depression
• have a condition that increases your risk of blood clots
• have a wasting disease (a disease that causes unintended weight loss) unrelated to prostate cancer
• have Dubin Johnson or Rotor syndromes (diseases that cause bilirubin to build up in the body)
• have reduced kidney function

Many medications can cause side effects. A side effect is an unwanted response to a medication when it is taken in normal doses. Side effects can be mild or severe, temporary or permanent.

The side effects listed below are not experienced by everyone who takes this medication. If you are concerned about side effects, discuss the risks and benefits of this medication with your doctor.

The following side effects have been reported by at least 1% of people taking this medication. Many of these side effects can be managed, and some may go away on their own over time.

Contact your doctor if you experience these side effects and they are severe or bothersome. Your pharmacist may be able to advise you on managing side effects.

• breast lumps (e.g., swelling and tenderness, skin irritation, pain)
• constipation
• decreased sexual interest or ability
• decreased fertility
• diarrhea
• dizziness
• general feeling of being unwell
• frequent urination
• hair loss
• headache
• heartburn
• hot flashes
• impotence
• nausea
• reduced (or increased) sexual interest
• skin bleeding, blistering, coldness, or discoloration
• swelling of the breasts or breast soreness
• tiredness or weakness
• unusual increase in hair growth
• vomiting
• weight changes

Although most of the side effects listed below don't happen very often, they could lead to serious problems if you do not seek medical attention.

Check with your doctor as soon as possible if any of the following side effects occur:

• breast milk production
• chills
• fever
• osteoporosis (e.g., thin, brittle bones; easily broken bones; back pain that increases when walking and standing)
• signs of anemia (low red blood cells; e.g., dizziness, pale skin, unusual tiredness or weakness, shortness of breath)
• signs of a blood clot in the arm or leg (tenderness, pain, swelling, warmth, or redness in the arm or leg) or lungs (difficulty breathing, sharp chest pain that is worst when breathing in, coughing, coughing up blood, sweating, or passing out)
• signs of clotting problems (e.g., unusual nosebleeds, bruising, blood in urine, coughing blood, bleeding gums, cuts that don't stop bleeding)
• signs of high blood sugar (e.g., frequent urination, increased thirst, excessive eating, unexplained weight loss, poor wound healing, infections, fruity breath odour)
• signs of liver problems (e.g., nausea, vomiting, diarrhea, loss of appetite, weight loss, yellowing of the skin or whites of the eyes, dark urine, pale stools)
• signs of low blood pressure (e.g., dizziness, blurred vision, fatigue, fainting or light-headedness when rising from a sitting or lying position)
• skin rash
• swelling of the arms, hands, feet, ankles or face
• symptoms of benign (noncancerous) brain tumours (e.g., constant headaches, hearing or vision changes, coordination difficulties, mood or personality changes, difficulty concentrating, nausea)
• symptoms of depression (e.g., poor concentration, changes in weight, changes in sleep, decreased interest in activities, thoughts of suicide)
• vision changes

Stop taking the medication and seek immediate medical attention if any of the following occur:

• signs of a serious allergic reaction (e.g., abdominal cramps, difficulty breathing, nausea and vomiting, or swelling of the face and throat)
• signs of bleeding in the stomach (e.g., bloody, black, or tarry stools; spitting up of blood; vomiting blood or material that looks like coffee grounds)
• signs of breathing problems (e.g., shortness of breath, troubled breathing, wheezing, or tightness in chest, fast or irregular breathing)
• signs of heart attack (e.g., sudden chest pain or pain radiating to back, down arm, jaw; sensation of fullness of the chest; nausea; vomiting; sweating; anxiety)
• signs of heart failure (e.g., shortness of breath, fatigue, swelling in legs, ankles, feet, rapid weight gain)
• signs of pancreatitis (e.g., abdominal pain on the upper left side, back pain, nausea, fever, chills, rapid heartbeat, swollen abdomen)
• signs of stroke (e.g., sudden or severe headache; sudden loss of coordination; vision changes; sudden slurring of speech; or unexplained weakness, numbness, or pain in arm or leg)

Some people may experience side effects other than those listed. Check with your doctor if you notice any symptom that worries you while you are taking this medication.

Before you begin using a medication, be sure to inform your doctor of any medical conditions or allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should use this medication.

Adrenal gland problems: Adrenal glands produce chemical messengers that are responsible for the normal function of the body's organs, including how your body responds to injury or stress. On rare occasions, cyproterone may cause your adrenal gland to function improperly. Your doctor may monitor your adrenal gland condition especially if you have experienced stress such as surgery, injury, or severe infection.

Alcohol: The effectiveness of cyproterone may be reduced if you consume alcohol. You should limit the amount of alcohol you drink when taking this medication.

Breathing problems: Difficulty breathing has been reported by people using cyproterone. This may be more likely to occur for people with conditions that make breathing difficult, such as asthma or chronic obstructive pulmonary disease (COPD). Report any increased problems breathing to your doctor.

Depression: Cyproterone use has occasionally been associated with an increased incidence of depressive mood changes, especially with start of therapy. You should notify your doctor if you've had depression in the past.

Diabetes: Cyproterone may cause an increase in blood sugar levels (may cause a loss of blood glucose control) and glucose tolerance may change. People with diabetes may find it necessary to monitor their blood sugar more frequently while using this medication.

If you have diabetes or are at risk for developing diabetes, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Drowsiness/reduced alertness: Cyproterone may affect the mental or physical abilities needed to drive or operate machinery, particularly when you first start taking this medication. Avoid driving, operating machinery, or performing other potentially hazardous tasks until you have determined how you are affected by this medication.

Heart disease: Cyproterone can cause fluid to accumulate in the body, causing your heart to have to work harder. If you have heart disease, report any rapid weight gain or puffiness of the hands, feet, or lower legs.

Kidney disease: Kidney disease or decreased kidney function may cause cyproterone to build up in the body, causing side effects. If you have decreased kidney function, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Liver disease: Cyproterone can cause damage to the liver. It usually develops after several months of treatment. Your doctor will monitor your liver function with blood tests if there are any symptoms or signs of liver damage. If you experience symptoms of liver problems such as fatigue, feeling unwell, loss of appetite, nausea, yellowing of the skin or whites of the eyes, dark urine, pale stools, abdominal pain or swelling, and itchy skin, contact your doctor immediately.

Pregnancy: Cyproterone should not be used by women.

Breast-feeding: Cyproterone should not be used by women.

Children: Cyproterone is not recommended for children.

There may be an interaction between cyproterone and any of the following:

• alcohol
• apalutamide
• "azole" antifungals (e.g., itraconazole, ketoconazole, voriconazole)
• carbamazepine
• cobicistat
• corticosteroids (e.g., dexamethasone, hydrocortisone, prednisone)
• cyclosporine
• diabetes medications (e.g., acarbose, canagliflozin,  glyburide, gliclazide, insulin, liraglutide, lixisenatide, metformin, saxagliptin)
• enzalutamide
• ethinyl estradiol
• HIV protease inhibitors (e.g., atazanavir, darunavir, ritonavir, saquinavir)
• lumacaftor and ivacaftor
• phenobarbital
• phenytoin
• pomalidomide
• primidone
• rifampin
• St. John's wort
• "statin" cholesterol medications (e.g., atorvastatin, lovastatin, simvastatin)
• testosterone and androgens

If you are taking any of these medications, speak with your doctor or pharmacist. Depending on your specific circumstances, your doctor may want you to:

• stop taking one of the medications,
• change one of the medications to another,
• change how you are taking one or both of the medications, or
• leave everything as is.

An interaction between two medications does not always mean that you must stop taking one of them. Speak to your doctor about how any drug interactions are being managed or should be managed.

Medications other than those listed above may interact with this medication. Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription), and herbal medications that you are taking. Also tell them about any supplements you take. Since caffeine, decongestants, alcohol, the nicotine from cigarettes, or street drugs can affect the action of many medications, you should let your prescriber know if you use them.