See also Warning section.
Because flutamide is usually used with other medications, the side effects may be caused by the other medications or their combination. Hot flashes, loss of sexual interest/ability, diarrhea, nausea, vomiting, and enlargement of male breasts may occur. Less common side effects include drowsiness. If any of these effects persist or worsen, tell your doctor or pharmacist promptly.
Diarrhea is a common side effect. Drink plenty of fluids as directed by your doctor to reduce your risk of losing too much body water. You may decrease dairy products, increase whole grains/vegetables/fruit, and stop any laxatives. Your doctor may prescribe anti-diarrhea medication (such as loperamide) to control your symptoms. Tell your doctor right away if you develop severe or persistent diarrhea or signs of dehydration (such as dizziness, decreased urination).
Flutamide may change the color of your urine to light orange-brown or yellow-green. This is not harmful.
Remember that your doctor has prescribed this medication because he or she has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects.
Tell your doctor right away if any of these rare but very serious side effects occur: mental/mood changes (such as depression, anxiety, nervousness), a breast lump, confusion, sudden severe tiredness, weakness, pale skin, bluish fingernails/lips/skin, fast heartbeat at rest, feeling short of breath at rest.
A very serious allergic reaction to this drug is rare. However, seek immediate medical attention if you notice any symptoms of a serious allergic reaction, including: rash, itching/swelling (especially of the face/tongue/throat), severe dizziness, trouble breathing.
This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist.
In the US - Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088 or at www.fda.gov/medwatch.
In Canada - Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345.