Your Guide to Anti-Androgens

Medically reviewed by Alan Carter, PharmD on February 5, 2018Written by Corinne O'Keefe Osborn on February 5, 2018

What are anti-androgens?

Androgens are hormones that regulate the development of sex characteristics. Typically, people born with male sex characteristics have high levels of androgens. People born with female characteristics have low levels of androgens. Instead, they have high levels of estrogens.

Anti-androgen drugs work by blocking the effects of androgens, such as testosterone. They do this by binding to proteins called androgen receptors. They bind to these receptors so that androgens can’t.

There are several types of anti-androgens. They’re usually taken with other medications or during certain surgical procedures.

How are they used?

Anti-androgens have many uses, from managing prostate cancer to reducing unwanted facial hair.

For women

All women naturally produce a small amount of androgens. However, some women produce more than others.

For example, women with polycystic ovary syndrome (PCOS) have higher androgen levels. This can cause excess hair growth, acne, and ovulation problems. Anti-androgens can help reduce these symptoms in women with PCOS.

Other conditions that cause high levels of androgens in women include:

Anti-androgens can help manage these conditions and prevent complications caused by high androgen levels in women. These complications include:

For transgender women and nonbinary people

For people in transition, anti-androgens can help block some of the masculinizing effects of testosterone. They can reduce some characteristically male traits, such as:

Anti-androgens are most effective for transgender women when taken with estrogen, the primary female sex hormone. In addition to triggering the development of feminine physical traits, such as breasts, estrogen also indirectly reduces testosterone levels. Taking anti-androgens with estrogen can help to both suppress masculine traits and promote feminine ones.

For people who identify as nonbinary, taking anti-androgens alone can help reduce masculine physical traits.

For men

Androgens stimulate cancer cell growth in the prostate. Lowering androgen levels, or preventing androgens from reaching cancer cells, can help slow down cancer. It may also shrink existing tumors.

In its early stages, prostate cancer cells rely on androgens to feed their growth. Anti-androgens work by blocking androgens from binding to androgen receptors in prostate cancer cells. This starves the cancer cells of the androgens they need in order to grow.

However, anti-androgens don’t stop androgen production. They’re often used in combination with other treatments, such as surgical or chemical castration. These combinations are also called:

  • combined androgen blockage
  • complete androgen blockade
  • total androgen blockade

What are some common ones?

There are several anti-androgens available, each with slightly different uses. Here’s a look at some of the most common ones.

Flutamide

Flutamide is a type of anti-androgen that’s used with other medications to treat certain types of prostate cancer. Flutamide binds to the androgen receptors in prostate cancer cells, which blocks androgens from binding to the receptors. This prevents androgens from encouraging prostate cancer cell growth.

Spironolactone

Spironolactone (Aldactone) is a type of anti-androgen that’s been used for 30 years to treat hormonal acne and excessive body hair. People transitioning may take it to reduce masculine traits. Although there’s little evidence to support its use, some doctors also prescribe it for female pattern baldness.

Cyproterone

Cyproterone was one of the first anti-androgens. It’s been used with other medications to treat women with PCOS. It’s also been shown to decrease testosterone levels and reduce the production of acne-causing oils.

It may also be used to reduce masculine traits in transgender women. However, due to its side effects, it’s generally not preferred.

What are the side effects?

Anti-androgens can produce a range of side effects, depending on the dose and type you take.

Some possible side effects include:

  • low sex drive
  • increased risk of depression
  • elevated liver enzymes
  • reduced facial and body hair
  • higher risk of birth defects if taken during pregnancy
  • hepatitis
  • liver injury
  • erectile dysfunction
  • diarrhea
  • breast tenderness
  • hot flashes
  • menstrual irregularity
  • skin rash
  • anti-androgen resistance, meaning the medication stops working

Your doctor can help you choose an anti-androgen that’s best suited for your needs and comes with the fewest side effects.

The bottom line

Anti-androgens have many uses for men, women, and people in gender transition, both on their own and in conjunction with other medications and treatments. However, anti-androgens are powerful drugs that can cause some serious side effects. Work with your doctor to weigh the pros and cons of taking anti-androgens.

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