Flutamide (Eulexin®)

Reviewed by: HU Medical Review Board | Last reviewed: September 2022 | Last updated: October 2022

Flutamide (Eulexin®) is a drug used to treat prostate cancer. It can be used for prostate cancer that is locally confined or prostate cancer that has spread to other areas of the body. It works by blocking the activity of androgen hormones. This is why flutamide is called an anti-androgen drug.1

The US Food and Drug Administration (FDA) approved flutamide to treat prostate cancer in 1989. It is usually used with a gonadotropin-releasing hormone (GnRH) agonist, which is also called a luteinizing hormone-releasing hormone (LHRH) agonist. These drugs help reduce androgen levels.1

Serious side effects are possible. Talk to your doctor about the risks and benefits of flutamide.1

What are the ingredients in flutamide?

The active ingredient in flutamide is flutamide.1

How does flutamide work?

Prostate cancers often use androgens to grow. Androgens are hormones that all people have and that serve several purposes in the body. Reducing the activity of androgens can slow prostate cancer growth.1,2

Flutamide blocks proteins called androgen receptors. Androgen hormones such as testosterone bind to and activate these androgen receptors. Blocking the androgen receptors lowers androgen activity. This can slow or stop the progression of prostate cancer.1,2

Your doctor will help determine whether flutamide is right for you. This decision depends on a number of factors, including the stage of your cancer and your physical condition. Flutamide may also be used to prevent a prostate cancer tumor flare caused by increased testosterone levels at the start of GnRH agonist treatment.1

What are the possible side effects?

The most common side effects of flutamide include:1,3

  • Hot flashes
  • Low sex drive (low libido)
  • Erectile dysfunction (impotence)
  • Diarrhea
  • Nausea
  • Vomiting
  • Enlarged male breast tissue (gynecomastia)

Flutamide has a boxed warning, the strictest warning from the FDA. It has this warning because of the risk of liver damage and possibly liver failure.1,3

Talk to your doctor if you notice symptoms of liver problems, including:1,3

  • Abdominal pain
  • Loss of appetite
  • Soreness or muscle aches (flu-like symptoms)
  • Weight loss
  • Nausea and vomiting
  • Extreme tiredness (fatigue)
  • Brown urine
  • Yellowing of the skin and/or whites of the eyes (jaundice)

These are not all the possible side effects of flutamide. Talk to your doctor about what to expect when taking flutamide. Call your doctor if you have any changes that concern you when taking flutamide.

Other things to know

Take flutamide as your doctor prescribes. It is taken as an oral tablet and should be taken in combination with a GnRH agonist. The combination of flutamide and a GnRH agonist is called a total androgen blockade.1,2

Your doctor may monitor your liver function with blood tests before and during treatment with flutamide. These tests can help identify whether you are having liver problems.1,3

Before beginning treatment with flutamide, tell your doctor about your full health history. Certain other health conditions and drugs may make taking flutamide less safe. Tell your doctor about:

  • Any allergies you have
  • Other medical conditions you have, especially liver problems
  • Whether you smoke or have smoked cigarettes in the past
  • All other medicines you take, including vitamins, supplements, and over-the-counter drugs

For more information, read the full prescribing information.

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