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What Is Leuprolide (Lupron®, Eligard®)?

Leuprolide is a Gonadotropin Releasing Hormone (GnRH) agonist (or LHRH agonist). Leuprolide is available under the brand names Lupron® and Eligard®. It is indicated for use as a palliative treatment option for individuals with advanced prostate cancer. Leuprolide is administered under the supervision of a physician via a subcutaneous (under the skin) or intramuscular (in a muscle) injection. The varying ways of receiving leuprolide depend on the brand name used. Individuals taking leuprolide should be closely monitored, especially during the first several weeks of treatment, as tumor flare can occur.

Tumor flare is the worsening of tumor symptoms early on in treatment that can lead to spinal cord compression and other adverse effects. Individuals taking leuprolide should also be monitored for increased blood sugar and the development of diabetes, as well as for cardiovascular complications and convulsions. Leuprolide is the active ingredient in Lupron and Eligard and acts as a Gonadotropin-Releasing Hormone (GnRH) agonist.1,2

How does leuprolide work?

Leuprolide is a Gonadotropin-Releasing Hormone (GnRH) agonist. This means, that its purpose is to activate the GnRH receptor by mimicking the receptor’s normal activator. 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. Leuprolide continuously activates a key receptor in the pathway to making testosterone, and eventually overwhelms the receptor.

When the receptor is overwhelmed, or desensitized, it stops making luteinizing hormone (LH) and follicle-stimulating hormone (FSH), which are key in making testosterone. This is also known as medical or chemical castration. However, a major concern with desensitizing the GnRH receptor is that before the receptor becomes overwhelmed, it will be continuously activated for the first few weeks of treatment. This means that more testosterone will be produced than usual, and could potentially cause a short term surge in tumor growth, known as Tumor Flare Phenomenon. Risk of tumor flare can be decreased by taking an antiandrogen with Lupron or Eligard.

What are the possible side effects of leuprolide?

Multiple clinical trials evaluated the safety and efficacy of leuprolide. The side effects of leuprolide vary slightly with the brand taken and way received, however the most common effects include GI disorders, joint disorders, general pain, swelling, respiratory disorders, headache, hot flashes, fatigue, urinary problems, and shrinking of the testicles. Injection or implantation site reactions are also possible while receiving leuprolide. This is not an exhaustive list of all potential side effects of leuprolide. Talk to your healthcare provider or pharmacist for further information.

Things to note about Leuprolide

Several rare but more serious side effects can accompany leuprolide including Tumor Flare Phenomenon, increased blood sugar, and injection or implantation site reaction. Additionally, leuprolide may increase an individual’s risk of developing diabetes and cardiovascular complications, including an increased risk of heart attack, stroke, and sudden cardiac death. Individuals taking leuprolide should also be monitored for convulsions. Leuprolide may also cause a decrease in bone mineral density, leading to osteoporosis (thinning of the bones).

Tumor Flare Phenomenon is possible while taking leuprolide, in which tumor growth is accelerated for a short time before it is halted. Alert your provider immediately if you notice any serious signs of Tumor Flare Phenomenon including:

  • Weakness or loss of feeling in legs
  • Have blood in the urine
  • Have trouble urinating or are unable to urinate
  • Experience new or worsening bone pain

You should also contact your provider if you notice any signs of an allergic reaction to the medication, including chest pain or difficulty breathing.

Before starting leuprolide talk to your provider if you:

  • Have any heart or blood vessel conditions such as irregular heart beat
  • Have a history of seizures or epilepsy
  • Are taking any medications for any cardiovascular conditions
  • Have high blood pressure
  • Have a condition that affects the strength of your bones
  • Are taking any other medications, vitamins, or herbal supplements

Dosing information

Leuprolide is injected intramuscularly or subcutaneously, depending on the formulation, under the supervision of your physician. The injection can come in various dosages and require different administration timelines. Your provider will determine the appropriate dosage and injection schedule for you; however, common dosages include 7.5 mg every month, 22.5 mg every 12 weeks, 30 mg every 16 weeks, and 45 mg every 6 months.1,2

Written by: Casey Hribar | Last reviewed: July 2019
  1. Lupron Depot Prescribing Information. June 2014. Available from:
  2. Eligard Prescribing Information. 2010. Available from:,021379s015,021488s016,021731s012lbl.pdf