7 Degarelix Side Effects You Should Know About

If you’ve been diagnosed with prostate cancer, you may have started hormone therapy as a part of your treatment plan. Many prostate cancers rely on the hormone testosterone as fuel to grow. By blocking the effects of testosterone in your body, hormone therapy can help slow down or stop prostate cancer growth.

There are a few ways to interrupt testosterone’s actions. A common way is by using medications like degarelix (Firmagon) or leuprolide (Lupron Depot, Eligard). These medications treat prostate cancer by lowering the amount of testosterone in your body.

For the most part, these are beneficial medications. But since medications like degarelix affect your hormones, there can be side effects. The good news is that there are often ways to manage these side effects if they happen.

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What is degarelix?

Degarelix is an injectable hormone therapy medication for advanced prostate cancer. It’s also known as a type of androgen deprivation therapy (ADT). It lowers testosterone levels within a few days of your first injection.

Degarelix is similar to leuprolide, but it works differently. Gonadotropin-releasing hormone agonists, like leuprolide, cause higher levels of testosterone at first, but then they go down over time. Gonadotropin-releasing hormone antagonists, like degarelix, cause an immediate drop in testosterone levels without making them go up first.

Since degarelix doesn't cause an initial increase in testosterone — also known as a testosterone flare — it tends to have fewer initial side effects compared to other hormone therapies. But there are still some side effects to keep in mind. We’ll discuss seven of them below.

1. Injection site reactions

Degarelix is given as a subcutaneous (under the skin) injection in your belly about once a month. Its most common side effect is related to the injection itself. In degarelix’s initial studies, about 35% of people experienced injection site reactions after their first injection. But these were much less common with later doses.

Reactions at the injection site can include redness, pain, and swelling. It's also normal to feel a small lump under the skin where you received the injection. The lump is a storage of medication that’s continually released in your body over the month. Injection site reactions are usually mild and resolve on their own within a few days.

There are also a few steps you can take to increase your comfort with your monthly injection. Here are a few tips for managing discomfort from injection site reactions:

• Wear loose-fitting clothing.

• Keep the injection site clean, and avoid scratching or rubbing the area.

• Apply a cool ice pack or cool compress to the injection site after each dose.

• Tell the healthcare professional who's giving the injection to use a different location for each dose.

2. Hot flashes

Another common degarelix side effect is hot flashes. During a hot flash, you may experience sudden feelings of warmth and redness throughout your face and neck. These symptoms can last from a few seconds to several minutes or more. You may also feel anxious or irritable. Hot flashes tend to get better over time as your body gets used to degarelix.

If the hot flashes are bothersome or don’t get better over time, your healthcare provider can prescribe medication to help keep them in check. Medications that may help with hot flash symptoms include clonidine, some antidepressants (such as venlafaxine and fluoxetine), or gabapentin.

Medications aren’t the only answer. In fact, it’s nice to avoid them when possible. These are some other ways to help manage hot flashes:

• Stay well hydrated

• Drink ice water or apply an ice pack during a hot flash

• Wear light-weight clothing

• Exercise regularly

• Meditate or practice relaxation techniques

• Avoid spicy foods, alcohol, and caffeine (when possible)

3. Weight changes

Degarelix can cause weight gain and a loss of muscle strength. About 9% of people have reported some kind of weight gain with degarelix.

Some tips to help combat the effects of weight gain include eating a healthy diet, lifting weights, and exercising regularly. Your healthcare provider can talk to you more about what to do if you experience bothersome body weight changes while taking degarelix.

4. Back and joint pain

Degarelix may cause back and joint pain for some people who take it. Up to 6% of people reported these side effects during clinical trials.

Back and joint pain from degarelix is usually mild. But if you have pain in your muscles or joints, over-the-counter pain relievers, like acetaminophen (Tylenol) or ibuprofen (Advil, Motrin), may offer some relief. A topical medication is another potential option if your pain is local to one area.

Ask your healthcare provider if medications like these are OK for you to take. They can also offer other pain management resources if your pain is more severe.

5. Certain heart rhythm changes

Although rare, degarelix can affect your heart rhythm. It can cause a heart rhythm problem called QT prolongation. You may be at a higher risk of QT prolongation if you have pre-existing heart problems or take other medications that affect your heart rhythm, like certain antibiotics, antidepressants, or antipsychotics.

Symptoms of QT prolongation can include lightheadedness, blurred vision, and fainting. If you experience symptoms like a racing heart, chest pain, or fluttering in your chest, you should seek medical help right away. To avoid or prevent problems like these, your healthcare provider may need to check your heart rhythm and blood work more often while taking degarelix.

6. Sexual and reproductive changes

Degarelix can affect your reproductive system. Lower testosterone levels can affect your sperm production, causing it to become irregular or stop altogether. You may also experience a lower sex drive or erectile dysfunction (ED). Talk to your healthcare provider about options for treating ED. Medications like sildenafil (Viagra) and tadalafil (Cialis) can help with ED.

It's also important to be aware that degarelix may cause birth defects if exposed to an unborn child. If you have a partner that’s able to become pregnant, ask your healthcare provider about potential birth control options while you’re taking degarelix.

7. Changes in certain lab tests

Degarelix can sometimes affect your liver and cause changes in certain liver enzymes (liver proteins). Higher levels of liver enzymes may be a sign of liver problems. About 10% of people who received degarelix had changes in their liver enzymes. However, these changes are usually mild and go away with time.

You can usually continue to receive degarelix despite changes in liver labs, but your healthcare provider may want to monitor your liver lab work while you’re taking degarelix.

When should I contact my healthcare provider about degarelix side effects?

Some degarelix side effects, such as injection site reactions and hot flashes, may get better over time as your body gets used to the medication. But make sure to tell your healthcare provider if you have any side effects that bother you or get worse at any point.

If you continue to have side effects, your healthcare provider may recommend changes to your medication routine to help manage certain side effects. In some cases, they may decide to switch you to a different medication. Other medication options for ADT for prostate cancer include leuprolide, goserelin (Zoladex), and relugolix (Orgovyx).

Certain side effects are also more severe than others. Let your healthcare provider know immediately if you experience any symptoms of heart rhythm problems, such as chest pain, abnormal heartbeats, or a fluttering feeling in your chest. You should also let them know if you think you’re having an allergic reaction to degarelix. Call 911 if you’re having breathing difficulties or swelling of the lips, mouth, or throat. These may be symptoms of a medical emergency.

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Written by:

Sonja Jacobsen, PharmD, BCPS, BCOP

Sonja Jacobsen, PharmD, BCPS, BCOP,  is a clinical oncology pharmacy specialist currently practicing in Seattle. She has been practicing as a pharmacist since 2015 and is licensed to practice in Washington state and North Carolina.

Edited by:

Joshua Murdock, PharmD, BCBBS

Joshua Murdock, PharmD, BCBBS, is a licensed pharmacist in Arizona, Colorado, and Rhode Island. He has worked in the pharmacy industry for more than 10 years and currently serves as a pharmacy editor for GoodRx.

Reviewed by:

Christina Aungst, PharmD

Christina Aungst, PharmD, is a pharmacy editor for GoodRx. She began writing for GoodRx Health in 2019, transitioning from freelance writer to editor in 2021.

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