Rarely, flutamide has caused severe (sometimes fatal) liver problems. Immediately tell your doctor if you develop symptoms of liver problems (such as nausea/vomiting that doesn't stop, stomach/abdominal pain that doesn't go away, loss of appetite, severe tiredness, dark urine, yellowing eyes/skin, aching muscles, joint pain). Liver problems can happen at any time while taking flutamide, but they occur most often during the first 3 months of treatment. Your doctor will tell you whether to stop or continue flutamide. Your doctor will monitor your liver function with blood tests while you take flutamide. Keep all medical and lab appointments. Avoid alcohol while taking flutamide.
Before taking flutamide, tell your doctor or pharmacist if you are allergic to it; or if you have any other allergies. This product may contain inactive ingredients, which can cause allergic reactions or other problems. Talk to your pharmacist for more details.
Before using this medication, tell your doctor or pharmacist your medical history, especially of: liver problems, a certain enzyme deficiency (glucose-6-phosphate dehydrogenase-G6PD), smoking, hemoglobin M disease.
This drug may rarely make you dizzy or drowsy. Alcohol or marijuana (cannabis) can make you more dizzy or drowsy. Do not drive, use machinery, or do anything that needs alertness until you can do it safely. Avoid alcoholic beverages. Talk to your doctor if you are using marijuana (cannabis).
Before having surgery, tell your doctor or dentist about all the products you use (including prescription drugs, nonprescription drugs, and herbal products).
Older adults may be more sensitive to the side effects of this drug, especially drowsiness.
This medication is not usually used in women. It is unlikely to be used during pregnancy or breastfeeding. Women who are pregnant or breastfeeding should avoid touching or accidentally taking this medication.
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 last or get worse, 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 dehydration. 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 diarrhea that is severe or doesn't stop, 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 this medication has been prescribed because your doctor 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 you have any serious side effects, including: 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, get medical help right away 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.
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