Zoladex (Goserelin) Side Effects and Tips To Reduce Them

Zoladex (also known by its generic name Goserelin and Prostap Injection) is a prescription medication for the treatment of prostate cancer in men. 

Zoladex is a type of hormone therapy drug (gonadotropin-releasing hormone-GnRH-agonist).

Prostap is designed to work by regulating testosterone levels in the body.

Like any other drug, Zoladex has potential side effects ranging from mild to serious. 

It is vital to note that not everyone taking Goserelin will experience all the side effects, and their severity will also vary in different persons. 

This article provides information on potential side effects of Zoladex injections, Zoladex side effects long term, how long they last, and how to manage them.

Common Side Effects Of Zoladex Injection

1) Hot Flashes

Hot flashes are one of the most common Zoladex side effects in prostate cancer patients. 

A hot flash is characterized by a sudden feeling of warmth over your neck, face, and chest and may result in sweating and reddening of your face.

How To Reduce Hot Flashes

  • Wear clothes that are made of natural fabrics (for example, cotton)
  • Wear clothes in thin layers so you can remove the layers when experiencing a hot flash
  • Keep your room temperature cool
  • Use bed sheets made of cotton
  • Drink cold beverages instead of hot ones
  • Avoid caffeinated beverages

Your healthcare professional may also prescribe medications to manage hot flashes.

2) Impotence/Erectile Dysfunction

Impotence or erectile dysfunction, characterized by an inability to have an erection, is also one of the common Zoladex side effects in prostate cancer patients. 

Some people undergoing Zoladex treatment may also experience changes in sexual libido.

How To Reduce Erectile Dysfunction

Your healthcare professional will help you manage the side effects related to reduced sexual drive and libido.

To manage the erection problems, the following treatments may be helpful:

  • Taking drugs before sex
  • Using vacuum pumps to improve blood circulation in the penile area
  • Applying creams or pellets to promote an erection
  • Using penile implants

Getting counseling and support, such as from a sex therapist, may also help you manage and cope with your problem.

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3) Fatigue/Tiredness

Fatigue is another common Zoladex side effect. Possible symptoms of fatigue include:

  • Weakness
  • Tiredness

How To Reduce Fatigue

You may take the following measures to manage fatigue:

  • Engage in regular gentle exercise (such as going for short walks)
  • Get plenty of sleep every night
  • Take a nap during the day
  • Try yoga and gentle stretching exercises

4) Skin Changes

Some patients may experience a skin reaction, such as an itchy rash, due to Zoladex use. Your healthcare professional may advise a cream or other medicine for the condition.

5) Breast Tissue Growth (Gynecomastia)

Treatment with Zoladex injections may cause breast tissue swelling or gynecomastia in some men. 

Your healthcare professional may guide you on managing the condition either using medicine such as Tamoxifen or surgery. 

6) Weight Gain

While uncommon, weight gain may be a side effect of Zoladex. Consult your healthcare professional if you experience weight-related concerns.

7) Loss Of Physical Strength And Muscle Mass

The Zoladex implant may lead to a reduction in physical strength and muscle mass for some individuals.

For instance, doing everyday activities such as climbing stairs, reaching overhead, etc., may feel difficult for you.

Doing resistance exercises, for instance, lifting weights (light) and doing gentle stretching, may help decrease loss of physical strength and maintain muscle mass.

8) Injury At The Zoladex Injection Site

Since Zoladex is placed beneath the skin, there is a small risk of injury at the injection site.

Some of the symptoms of an injury at the injection site are:

  • Hematoma (collection of blood beneath the skin)
  • Hemorrhage (severe bleeding)
  • Irritation or pain at the site of injection

You may also develop serious symptoms due to injury at the injection site. Contact your healthcare professional immediately if you experience any of the following symptoms after getting Zoladex implant:

  • Dizziness
  • Pain in the belly
  • Shortness of breath
  • Low blood pressure
  • Bloating or swelling of the stomach

The risk of developing these side effects is increased if you take blood thinning drugs or your body mass index is low. 

Your healthcare professional will do careful monitoring both before and after inserting the Zoladex implant. 

Injection site injuries on the skin are usually temporary and get better on their own. You may take an OTC pain-relieving medicine to alleviate pain.

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Serious Side Effects of Goserelin

Although uncommon, serious side effects may occur in certain patients using Zoladex.

Contact your healthcare professional promptly if you experience any severe Zoladex side effects.

1) Depression

You may develop the following symptoms:

  • Mood swings
  • Loss of concentration
  • Trouble making decisions
  • Loss of interest in activities or hobbies
  • Feeling pessimistic

You may talk to your healthcare professional if you develop any of these symptoms. They may suggest treatment options such as medicines, counseling, etc.

2) High Blood Sugar Levels

Zoladex may raise the levels of blood sugar and cause insulin resistance. If you have diabetes, your levels may even be higher.

You may develop the following symptoms:

  • Fatigue
  • Increased thirst
  • Headache
  • Trouble concentrating
  • Urinary frequency

3) Hypercalcemia (high blood levels of calcium)

You may develop the following symptoms:

  • Pain in the belly
  • Constipation
  • Frequent urination
  • Extreme thirst
  • Memory problems
  • Irritability

4) Tumor Flare

Zoladex increases the hormone levels for a very short duration during the initial few weeks of therapy. 

This may result in the growth of the cancerous tissue (tumor) for a short duration before Zoladex produces its full effect. This phenomenon is referred to as tumor flare.

In rare instances, the symptoms of prostate cancer may worsen due to the tumor flare. A tumor flare usually gets better on its own; however, it may cause serious symptoms in some individuals.

Serious symptoms and signs of a tumor flare are:

  • Blood in urine
  • Trouble during urination
  • Not able to pass urine
  • New bone pain/worsening of bone pain
  • Loss of feeling or weakness in legs

5) Spinal Cord Compression (the pressure on the spinal cord is increased)

You may develop the following symptoms:

  • Burning pain spreading to the arm, legs, or buttocks
  • Numbness, weakness, or cramping in the legs or arms
  • Loss of sensation in the feet
  • Stiffness and pain in the neck or back

6) Long QT Syndrome (a rare condition in which the heart rhythm becomes irregular)

You may develop the following symptoms:

  • Fainting
  • Seizures
  • Irregular heartbeat

If you experience any of the symptoms and signs of serious Zoladex side effects, call your healthcare professional immediately. 

How Long Do Zoladex’s Side Effects Last?

Most of the mild Zoladex side effects get better within some days or a few weeks. However, if they don’t get better or become severe, you should talk to your healthcare professional.

What Are The Long-Term Side Effects Of Zoladex Injection?

Though less common, Zoladex injection may result in long-term side effects. Some of the long-term Zoladex side effects are:

1) Osteoporosis (Bone Thinning)

Taking Zoladex implant for a long time may result in the thinning of bones (loss of bone density or bone mass), a condition known as osteoporosis. 

The latter raises the risk of bone fractures, even after stopping Zoladex.

How To Manage Osteoporosis

  • Your healthcare professional may prescribe drugs such as bisphosphonates to increase bone mass.
  • Engage in regular physical exercise such as walking
  • Eat a healthy and well-balanced diet
  • Take vitamin D and calcium supplements as advised by your healthcare professional.

2) Heart (Cardiovascular) Problems

One of the other possible long-term Zoladex side effects is an increased risk of heart problems such as stroke and heart attack.

You should inform your healthcare professional immediately if you develop any symptoms of heart problems such as:

  • Tightness or heaviness in the chest
  • Chest pain
  • Dizziness
  • Feeling breathless
  • Sudden weakness or numbness of the arm, leg, or face

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Side Effects Of Coming Off Prostap Injection

There is a risk that your prostate cancer may grow once you stop Zoladex. This may result in the occurrence of previous symptoms of cancer, such as trouble urinating or bone pain.


Zoladex is a drug that is used in the treatment of prostate cancer in men. Like other medicines, it may produce various side effects (both mild and severe), some of which are more common than others.

You may talk to your healthcare professional about ways to manage the side effects caused by Zoladex. Most of the emotional and sexual side effects go away after stopping Zoladex.

Make sure to inform your physician about all supplements and medicines that you are taking, including herbal medicines, as some of these may interact with the therapy.

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  1. Shparyk IaV. [Zoladex: new approaches to hormone therapy]. Lik Sprava. 1996 May-Jun;(5-6):44-50. Ukrainian. PMID: 9377399.
  2. Popko AS, Dokshin KL. “Zoladeks” (ICI) v terapii bol’nykh rakom predstatel’noĭ zhelezy [Zoladex (ICI) in the therapy of prostatic cancer patients]. Urol Nefrol (Mosk). 1996 Nov-Dec;(6):53-5. Russian. PMID: 9036615.
  3. Shim M, Bang WJ, Oh CY, Lee YS, Cho JS. Effectiveness of three different luteinizing hormone-releasing hormone agonists in the chemical castration of patients with prostate cancer: Goserelin versus triptorelin versus leuprolide. Investig Clin Urol. 2019 Jul;60(4):244-250. doi: 10.4111/icu.2019.60.4.244. Epub 2019 May 21. PMID: 31294133; PMCID: PMC6607074.
  4. National Cancer Institute. Hormone Therapy for Prostate Cancer.
  5. National Cancer Institute. Hot Flashes and Night Sweats.

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