Chemical Castration: Treatment, Procedure & Side Effects (2025)

What happens before chemical castration?

Before a healthcare provider suggests chemical castration, they must know if the type of cancer you have might respond well to chemical castration. They’ll recommend tests to determine what kind of cancer you have and its stage. Tests may include:

• CT scan
• PET scan
• Endoscopy
• Biopsy
• Blood tests for cancer

If the goal is to permanently reduce your testosterone, providers may discuss an orchiectomy (or-kee-EK-tuh-mee) with you. An orchiectomy is a procedure that removes one or both of your testicles to permanently reduce your testosterone levels. They may also suggest a subcapsular (suhb-KAP-suh-ler) orchiectomy. A subcapsular orchiectomy only removes the testicular tissue that makes testosterone.

What happens during chemical castration?

Chemical castration is an ongoing treatment. A healthcare provider will usually administer the drugs as injections or implants under your skin. But you may take some drugs as a pill. Depending on the specific drug and dosage amount, you may need repeated treatments anywhere from monthly to only once a year.

Chemical castration to treat prostate cancer can work in one of the following ways:

• Decreasing the production of androgens in your testicles
• Preventing androgens from being able to work in your body
• Stopping any other parts of your body from producing androgens

What drugs are used in chemical castration for prostate cancer?

The categories of chemical castration medications that healthcare providers use to treat prostate cancer include:

• Gonadotropin-releasing hormone (GnRH) agonists or GnRH analogs
• GnRH antagonists
• Antiandrogen treatments
• Androgen synthesis inhibitors

GnRH agonists or GnRH analogs

These medications stop your pituitary gland from releasing luteinizing hormone. Luteinizing (LOO-tee-in-ny-zing) hormone tells your testicles to make testosterone.

First, GnRH agonists or analogs cause a high level of hormone that your body eventually ignores. At that point, your testosterone levels may increase (testosterone flare). You may need antiandrogen therapy at the same time to help with side effects.

In the U.S., drugs in this category include:

• Goserelin (Zoladex®)
• Histrelin (Supprelin® or Vantas®)
• Leuprolide (Camcevi®, Eligard® or Lupron®)
• Triptorelin (Trelstar® or Triptodur®)

Another name for GnRH agonists and analogs is luteinizing-hormone releasing hormone (LHRH) agonists and analogs.

GnRH antagonists

These medications prevent testosterone production without causing a testosterone flare. In the U.S., drugs in this category include:

• Degarelix (Firmagon®)
• Relugolix (Orgovyx®)

Antiandrogen treatments

These drugs stop your body from using androgens. Healthcare providers commonly use antiandrogen treatments when chemical castration is no longer working well. They may use this in combination with chemical castration. In the U.S., antiandrogen drugs may include:

• Flutamide (Eulexin®)
• Bicalutamide (Casodex®)
• Apalutamide (Erleada®)
• Nilutamide (Nilandron®)
• Enzalutamide (Xtandi®)
• Darolutamide (Nubeqa®)

Another name for this therapy is complete androgen blockage.

Androgen synthesis inhibitors

Androgen synthesis inhibitors prevent the production of androgens anywhere in your body. They stop the production of the enzyme CYP17. CYP17 is necessary for any tissue to make testosterone, including prostate cancer tissue.

In the U.S., androgen synthesis inhibitor drugs may include:

• Aminoglutethimide (Cytadren®)
• Ketoconazole (Nizoral®)
• Abiraterone (Yonsa® or Zytiga®)

Can estrogen treat prostate cancer?

At one time, healthcare providers used the sex hormone estrogen to treat prostate cancer. But because of the side effects, providers don’t usually recommend it anymore.

What happens during chemical castration to treat breast cancer?

Healthcare providers may suggest chemical castration to treat breast cancer in females. Blocking hormones can help treat breast cancer tumors that feed on estrogen and/or progesterone. But chemical castration isn’t a permanent treatment for breast cancer tumors. Providers may recommend removing your ovaries (oophorectomy). Your ovaries help make estrogen and progesterone, which can fuel certain types of breast cancer.

Other names for chemical castration to treat breast cancer include:

• Hormone therapy for breast cancer
• Endocrine therapy

What treatments affect estrogen production or use?

Medications that affect estrogen production or use include:

• Selective estrogen receptor modulators, such as tamoxifen (Nolvadex® or Soltamox®) and toremifene (Fareston®), in pill form
• Selective estrogen receptor degraders, such as fulvestrant (Faslodex®), as an injection
• Aromatase inhibitors, such as anastrozole (Arimidex®), exemestane (Aromasin®) and letrozole (Femara®), as pills

What treatments suppress the ovaries?

Treatments that suppress your ovaries include:

• LHRH analogs, including goserelin and leuprolide, which cause temporary menopause
• Chemotherapy, which may permanently damage your ovaries

What should I expect after a chemical castration?

Chemical castration drugs start working as soon as you start the treatment. They keep working as long as you take them. But over time, prostate cancers may continue to grow, even if your androgen levels are very low (castration-resistant tumors). If you have a castration-resistant tumor, a healthcare provider may recommend different treatments, such as surgically removing your prostate (prostatectomy) or testicles.

After chemical castration, you’ll have a low sex drive (libido) and a reduced response to mental or physical stimulation. For example, you may not get an erection from watching or reading erotic material or touching your genitals and other sensitive parts of your body. You also may not think about sexual intercourse as often.