Skip to Accessibility Tools Skip to Content Skip to Footer

What Is Degarelix (Firmagon®)?


Firmagon® (degarelix) is a Gonadotropin Releasing Hormone (GnRH) receptor antagonist. It is indicated for use in individuals with advanced prostate cancer. Degarelix is administered as a subcutaneous (under the skin) injection in your abdominal area. Individuals taking degarelix should also be monitored for cardiovascular complications, including disorder of the heart’s electrical activity.

What are the ingredients in degarelix?

The active ingredient in degarelix is degarelix, the Gonadotropin-Releasing Hormone (GnRH) receptor antagonist.

How does degarelix work?

Degarelix’s active ingredient is a Gonadotropin-Releasing Hormone (GnRH) receptor antagonist. This means, that its purpose is to block the GnRH receptor. Prostate cancer tumors are often fueled to grow by androgens, including testosterone. Turning off the body’s ability to produce testosterone, or reducing the amount made can potentially halt tumor growth. Degarelix blocks a key receptor in the pathway to making testosterone. When this receptor is deactivated, it decreases luteinizing hormone (LH) and follicle-stimulating hormone (FSH), which are key in making testosterone. When the making of these hormones is suppressed, testosterone production is decreased as well. This is also known as medical or chemical castration.

What are the possible side effects of degarelix?

Multiple clinical trials evaluated the safety and efficacy of degarelix. The most common side effects of degarelix include hot flashes, increased weight, decreased sex drive, erectile dysfunction, and increases in some liver enzymes. Injection site reactions are also possible while receiving degarelix, and are typically accompanied by swelling, redness, and pain. This is not an exhaustive list of all potential side effects of degarelix. Talk to your healthcare provider or pharmacist for further information.

Things to note about degarelix

Several rare but more serious side effects can accompany degarelix including serious allergic reactions and disorder of the heart’s electrical activity. Individuals should be closely monitored for signs of these serious conditions. Signs of a serious allergic reaction that should be brought to your provider’s attention immediately are:

  • Severe itching
  • Trouble breathing or wheezing
  • Swelling of your face, lips, mouth, or tongue

Before starting degarelix talk to your provider if you:

  • Have any heart problems including long QT syndrome
  • Have problems with the levels of sodium, calcium, potassium, or magnesium in your blood
  • Have kidney or liver problems
  • Have any other medical conditions
  • Are currently taking any other medications, vitamins, or herbal supplements

Dosing information

Degarelix is administered as a subcutaneous injection (under your skin). Your healthcare provider will administer the injection for you into your abdomen. Your provider will help you determine the best dosage and administration schedule for your situation, however, a typical dosing consists of 240 mg of degarelix given as two 120 mg injections one time to start, followed by one 80 mg injection every 28 days.1

Written by: Casey Hribar | Last reviewed: July 2019
  1. Firmagon Prescribing Information. Jul 2016. Available from: