Flutamide

Key facts

• Flutamide is a non-steroidal antiandrogen. It blocks testosterone and other male hormones from acting on cells, including prostate cancer cells that depend on them to grow.
• It is taken as a capsule, usually three times a day, generally alongside another treatment that lowers testosterone production (such as an LHRH agonist or surgery).
• Flutamide can cause serious liver injury, including rare fatal cases. Liver function tests are done before starting and are checked regularly, especially in the first few months.
• Seek urgent care for yellowing of the skin or eyes, dark urine, severe nausea, or unexplained abdominal pain.

What flutamide treats

Flutamide is used with other hormone-lowering treatment for prostate cancer, usually at the start of therapy to blunt the brief testosterone surge that LHRH agonists can cause, and sometimes for longer-term combined androgen blockade. It is not a treatment for benign prostate enlargement.

How flutamide works

Prostate cancer cells often rely on testosterone binding to androgen receptors to keep growing. Flutamide attaches to those receptors instead, blocking testosterone from binding and slowing the cancer's growth signal.

Before you take it

• Do not take flutamide if you have significant liver disease or a known allergy to it.
• Tell your prescriber about any history of liver problems, heavy alcohol use, or other medicines that affect the liver, since these raise the risk of liver injury.
• Flutamide is not for use in women; it is not suitable for anyone who is or may become pregnant.
• Blood counts and liver function are usually checked before treatment starts and at intervals afterward.

Side effects

Common effects include hot flushes, reduced sex drive, breast tenderness or enlargement, and mild stomach upset, most related to the drop in male hormone activity.

Stop and seek urgent medical care for any of these:

• Yellowing of the skin or eyes, dark urine, or persistent nausea and abdominal pain (signs of liver injury).
• Unusual tiredness, loss of appetite, or flu-like symptoms that do not improve.
• Shortness of breath or chest pain.
• Unexplained bruising or bleeding.

Safety essentials

• Liver injury is the defining risk of flutamide. Liver function tests are required before treatment and monitored regularly, most closely during the first four months; treatment is stopped if results worsen or symptoms of liver trouble appear.
• Report any yellowing of the skin or eyes, dark urine, or unusual fatigue to your prescriber immediately rather than waiting for your next scheduled test.
• Avoid or limit alcohol, which adds to the strain on the liver during treatment.

This page is educational and does not replace advice from a doctor or pharmacist who knows your health history.