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Degarelix (Firmagon®)

OncoLink Team
Last Modified: September 23, 2015

Pronounced: DEG-a-REL-ix
Classification: Antiandrogen

About Degarelix

Degarelix is a man-made form of a protein that blocks the production of gonadotropin-releasing hormone (GnRH) by the pituitary gland. GnRH stimulates the testes to produce testosterone. By blocking GnRH, Degarelix reduces the body's level of testosterone. Testosterone affects the growth of the prostate gland and any cancer cells that may be present.

How to Take Degarelix

Degarelix is given as a subcutaneous injection (SQ, under the skin), every 4 weeks. Two injections are given for the first dose. Subsequent doses are one injection. The injection is designed to slowly release the medication over the next 4 weeks.

Possible Side Effects of Degarelix

There are a number of things you can do to manage the side effects of degarelix. Talk to your doctor or nurse about these recommendations. They can help you decide what will work best for you. These are some of the most common side effects:

Hot Flashes

There are a few things you can do to help with hot flashes. Several medications have been shown to help with symptoms, including clonidine (a blood pressure medication), low doses of certain antidepressants (such as venlafaxine and Prozac), and gabapentin. Non-medical recommendations include:

  • Keep well-hydrated with eight glasses of water daily.
  • Drink ice water or apply an ice pack at the onset of a hot flash.
  • Wear cotton or lightweight, breathable fabrics and dress in layers so you can adjust as needed.
  • Exercise on a regular basis.
  • Try practicing meditation or relaxation exercises to manage stress, which can be a trigger.
  • Avoid triggers such as warm rooms, spicy foods, caffeinated beverages, and alcohol.

Injection Site Reactions

The injection site may become red, swollen, tender or you may be able to feel a lump. These side effects are temporary. The injection is given in your abdomen. Make sure the area will not have any pressure on it from belts, waistbands or other types of clothing.

Breast Tenderness or Increase in Breast Tissue

An increase in breast tissue (gynecomastia) or breast tenderness may develop. Your healthcare team can suggest medications to relieve the tenderness. In rare cases, radiation can be given to relieve severe tenderness.

Weakening of the Bones (Osteoporosis)

Men who take hormone therapy for extended periods of time are at risk for bone thinning (osteoporosis). You may be advised to take calcium and vitamin D supplements to help prevent bone loss. Weight bearing exercise and a healthy diet rich in calcium and vitamin D can also help protect your bone health. You may have a bone density scan (DEXA scan) to assess your bone health. If your physician determines that you are at high risk of developing osteoporosis, they may recommend additional treatment with a type of medication called a bisphosphonate to help strengthen the bones.

Sexual and Reproductive Changes

This drug can affect your reproductive system, resulting in sperm production becoming irregular or stopping permanently. In addition, you may experience erectile dysfunction or a decreased desire for sex during treatment. Talk to your urologist about options for treating erectile dysfunction.

Exposure of an unborn child to this medication could cause birth defects, so you should not father a child while on this medication. Effective birth control is necessary during treatment, even if you believe you are not producing sperm.  

Other Side Effects

Some men experience weight gain, for which exercise and dietary changes may be helpful. Injection site reactions (redness, swelling and pain) have also been reported. In clinical trials, some patients had increases in blood tests that evaluate liver function. These abnormalities resolved when the medication was stopped.

This medication can effect the electrical conduction in your heart muscle (called QT prolongation). Make sure your provider is aware of any history of heart problems or heart medications you may be taking.


If you have questions or concerns about the medication that you have been prescribed, please contact your healthcare team. OncoLink is designed for educational purposes only and is not engaged in rendering medical advice or professional services. The information provided through OncoLink should not be used for diagnosing or treating a health problem or a disease. It is not a substitute for professional care. If you have or suspect you may have a health problem, you should consult your health care provider.


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