What are the common side effects of Degarelix?

Pain, redness or swelling where the shot was given. Hot flashes. Weight gain. Feeling tired. Less interest in sex or trouble getting an erection. Changes in liver blood tests.

When should I call my care team while taking Degarelix?

A fast, pounding or uneven heartbeat, or feeling faint; Trouble breathing, swelling of the face or throat, or hives; A shot spot that becomes very red, hot, swollen or leaks pus; Yellow skin or eyes, or dark urine; New chest pain.

Degarelix

Say it: deg-a-REL-ix · Brand names: Firmagon

Degarelix is a hormone shot that quickly lowers testosterone to slow the growth of prostate cancer.

What it is

Most prostate cancers need the male hormone testosterone to grow. Degarelix blocks the brain signal that tells the testicles to make testosterone. Testosterone levels drop within a few days, without the short rise in testosterone that some other hormone shots cause.

Often used for

advanced prostate cancer

How you get it

You get degarelix as a shot under the skin of your belly at a clinic. The first visit is usually two shots, then one shot about once a month. Your schedule may be different.

Common side effects and what helps

Pain, redness or swelling where the shot was given. A cool cloth on the spot can help.
Hot flashes. Dress in layers and keep cool drinks nearby.
Weight gain. Try to stay active and eat plenty of vegetables.
Feeling tired. Rest and short walks can help.
Less interest in sex or trouble getting an erection. It is okay to talk with your team about this.
Changes in liver blood tests. Your team will check these.

Call your care team right away if you have

A fast, pounding or uneven heartbeat, or feeling faint
Trouble breathing, swelling of the face or throat, or hives
A shot spot that becomes very red, hot, swollen or leaks pus
Yellow skin or eyes, or dark urine
New chest pain

Before you start, tell your team

If you have heart problems, including a heart rhythm problem called long QT
If you have liver or kidney problems
If you have weak bones (osteoporosis)
All the medicines you take, including vitamins, herbs and supplements

Good to know

Lowering testosterone can affect the heart rhythm. Your team may check a heart tracing (ECG) and blood salts.
Long-term low testosterone can thin your bones. Your team may suggest bone scans, calcium and vitamin D.
You will have blood tests to check your PSA (prostate specific antigen) and liver.

Questions to ask

How often will I need this shot?
How will we know if it is working?
What can I do about hot flashes?
Should I take anything to protect my bones?

Side effect guides

Sources

Quick answers

What is Degarelix?: Degarelix is a hormone shot that quickly lowers testosterone to slow the growth of prostate cancer. Brand names: Firmagon.
What is Degarelix used for?: advanced prostate cancer.
How is Degarelix given?: You get degarelix as a shot under the skin of your belly at a clinic. The first visit is usually two shots, then one shot about once a month. Your schedule may be different.
What are the common side effects of Degarelix?: Pain, redness or swelling where the shot was given. Hot flashes. Weight gain. Feeling tired. Less interest in sex or trouble getting an erection. Changes in liver blood tests.
When should I call my care team while taking Degarelix?: A fast, pounding or uneven heartbeat, or feeling faint; Trouble breathing, swelling of the face or throat, or hives; A shot spot that becomes very red, hot, swollen or leaks pus; Yellow skin or eyes, or dark urine; New chest pain.

Last updated: 2026-10-27. Medically reviewed by Veli Bakalov, MD, medical oncologist (October 2026). General education from Step by Step, the patient portal of HemeOncBuddy.