Flutamide belongs to a group of medications known as nonsteroidal antiandrogens. Nonsteroidal antiandrogens such as flutamide block the effect of the male hormone testosterone in the body.

Prostate cancer cells require testosterone in order to grow and reproduce. Flutamide is used in combination with a hormone therapy that reduces the amount of testosterone in the body (e.g., leuprolide) for the treatment of prostate cancer.

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.

The recommended dose is 250 mg 3 times daily at 8-hour intervals. This treatment should be started at the same time as treatment with an LHRH analogue (e.g., leuprolide) or after surgical removal of the testicles.

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 that you are taking the medication without consulting your doctor.

Flutamide may be taken with food or on an empty stomach.

It is important to take this medication exactly as prescribed by your doctor. If you miss a dose, take it as soon as possible and continue with your regular schedule. If it is almost time for your next 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.

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

Do not take flutamide if you:

• are allergic to flutamide or any ingredients of the medication
• are female
• have severely reduced liver 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.

• appetite changes
• constipation
• diarrhea
• dizziness
• drowsiness
• headache
• hot flashes
• impotence
• nausea
• indigestion
• nervousness
• reduction in sexual desire
• sleeping problems
• swelling of breasts with pain or tenderness
• vomiting

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:

• anxiety
• blurred vision
• confusion
• cough or hoarseness
• increased blood pressure
• itching
• joint or muscle pain
• shortness of breath
• signs of anemia (low numbers of red blood cells; e.g., unusual tiredness or weakness, pale coloured lips, fingernails, or palms of hands)
• signs of bleeding, e.g.:
  • blood in stools
  • blood in urine
  • bloody nose
  • coughing blood
  • cuts that don't stop bleeding
• signs of depression, e.g.:
  • changes in sleep
  • changes in weight
  • decreased interest in activities
  • poor concentration
  • thoughts of suicide
• signs of infections, e.g.:
  • fever or chills
  • headache
  • listlessness
  • prolonged dizziness
  • severe diarrhea
  • shortness of breath
  • stiff neck
  • weight loss
• signs of liver problems, e.g.:
  • dark urine
  • diarrhea
  • loss of appetite
  • nausea
  • pale stools
  • vomiting
  • weight loss
  • yellowing of the skin or whites of the eyes
• skin rash
• swelling of face, fingers, feet or lower legs
• unusual tiredness or weakness

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

• signs of heart attack or heart problems, e.g.:
  • chest pain
  • pain stretching down the shoulder and arm
  • pressure on the chest
  • shortness of breath or difficult or troubled breathing

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.

Anemia: Flutamide may cause low levels of red blood cells. If you experience symptoms of reduced red blood cell count (anemia) such as shortness of breath, feeling unusually tired, or pale skin, contact your doctor as soon as possible.

Your doctor will do blood tests regularly to monitor the number of specific types of blood cells, including red blood cells, in your blood.

Heart problems: Flutamide may cause fluid retention and swelling. As a result, there is an increased amount of work for the heart to pump the blood around the body. People with problems such as high blood pressure and congestive heart failure are more likely to feel this effect. People with heart problems should discuss with their doctor how this medication may affect their medical condition, how their medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Liver function: Flutamide is broken down and removed from the body by the liver and may cause liver problems. People with liver disease or decreased liver function should discuss with their doctor how this medication may affect their medical condition, how their medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

If you experience symptoms of liver problems (e.g., abdominal pain, persistent vomiting, feeling unwell, fever, itching, yellowing of the skin and eyes, dark urine), contact your doctor immediately.

Osteoporosis: Long-term use of medications such as flutamide has been shown to cause reduced bone strength and may increase the risk of bone fractures. If you have osteoporosis or are at increased risk of developing osteoporosis, 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.

Pregnancy: This medication is not intended for women to use. The safety and effectiveness of this medication has not been established for pregnant women.

Breast-feeding: This medication is not intended for women to use. Therefore it should not be used by breast-feeding women.

Children: The safety and effectiveness of using this medication have not been established for children.

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

• antiarrhythmics (e.g., amiodarone, disopyramide, quinidine, sotalol)
• "azole" antifungals (e.g., itraconazole, ketoconazole, voriconazole)
• benzocaine
• bupivacaine
• chlorpromazine
• dapsone
• hexylresorcinol
• lidocaine
• macrolide antibiotics (e.g., azithromycin, clarithromycin)
• methadone
• ondansetron
• quinine
• prilocaine
• quinine
• quinolone antibiotics (e.g., ciprofloxacin, norfloxacin, ofloxacin)
• tetracaine
• theophylline
• tricyclic antidepressants (e.g., amitriptyline, nortriptyline)
• warfarin

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 you are taking. Also tell them about any supplements you take. Since caffeine, 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.