Testosterone Blockers – Definition, Mechanism, Uses, and Side Effects (2023)


Androgens are hormones responsible for the development of sexual traits. Those with male attributes typically exhibit elevated androgen levels, while individuals with female attributes usually display lower androgen concentrations and increased estrogen levels.

Testosterone blockers inhibit the effects of testosterone by binding to proteins known as androgen receptors, preventing testosterone from interacting with them. A variety of testosterone blockers exist, which can be administered alongside other treatments or during specific surgical procedures.

In this article, we will cover the uses of testosterone blockers, then discuss some commonly prescribed types. Finally, we will take a look at some side effects of these drugs.

The uses of testosterone blockers

The uses of testosterone blockers are diverse and include:

For women

Although most women tend to produce minimal androgens, some may generate higher levels than others. For instance, women with polycystic ovary syndrome (PCOS) often have increased testosterone concentrations, leading to excessive hair growth, acne, and ovulation issues. Testosterone blockers can effectively alleviate these symptoms.

Additionally, testosterone blockers can help with other medical conditions that contribute to elevated testosterone levels in women, such as adrenal hyperplasia, ovarian tumors, and adrenal gland tumors.

A few complications of elevated testosterone levels in women are diabetes, high cholesterol, high blood pressure, and heart disease.

For transgender and nonbinary individuals

For individuals undergoing gender transition, testosterone blockers can help counteract some of the masculinizing effects of this hormone. They can diminish some male traits, such as male pattern baldness, facial hair growth, and morning erections.

Testosterone blockers often yield the most effective results for transgender women when used in conjunction with estrogen, which is the primary female sex hormone. Aside from initiating the development of feminine physical characteristics like breasts, estrogen also indirectly lowers testosterone levels.

Administering testosterone blockers with estrogen helps individuals to transition from masculine traits to feminine ones.

For nonbinary individuals, taking testosterone blockers alone can effectively reduce masculine physical traits.

For men

Androgens may be responsible for stimulating cancer cell growth in the prostate. By reducing testosterone levels or hindering the hormones from reaching cancer cells, testosterone blockers can decelerate cancer progression and potentially shrink existing tumors.

In the initial stages, prostate cancer cells depend on androgens to fuel their growth. Testosterone blockers function by preventing testosterone from binding to androgen receptors in prostate tissues, effectively halting the growth of cancer.

Keep in mind that testosterone blockers do not stop androgen production. As a result, medical professionals often combine testosterone blockers with other treatments, such as surgical or chemical castration. These combinations are also referred to as combined androgen blockage or total androgen blockade.

The benefits of testosterone blockers for gender transitioning

Gender transitioning can be a long and challenging journey. Many individuals opt for testosterone blockers as part of their medical plan to attain a more “feminine” hormonal balance.

While there are numerous benefits to testosterone blockers in the long term, you may notice the following effects right away:

  1. Enhanced breast growth – Taking testosterone blockers during transition can suppress testosterone action and elevate estrogen levels, leading to increased breast development.
  2. Mood improvement – As estrogen levels rise, mood can also improve. This is particularly beneficial for individuals experiencing depression or anxiety.
  3. Boosted libido – Sex drive can also be enhanced in transitioning individuals, helping you restore a more natural level.
  4. Reduced body hair – A major benefit of testosterone blockers is the reduction of body hair. This can be greatly beneficial for individuals dealing with gender dysphoria due to unwanted hair, making the transition process smoother.

Before you decide to take these medications, we recommend that you speak with your healthcare provider for tailored medical advice.

The most common testosterone blockers

Several testosterone blockers are available with unique applications.

Here is an overview of the most common types:


Flutamide is a testosterone blocker that we typically use with other medications to treat specific prostate cancer types. It functions by binding to androgen receptors in prostate tissues, thus inhibiting androgens from attaching to the receptors. This process prevents androgens from promoting prostate cancer growth.


Spironolactone (Aldactone) is another testosterone blocker that has a long history in the medical field. More specifically, doctors prescribe this medication to address hormonal acne and excessive body hair. Individuals undergoing gender transition may take it to diminish masculine traits.

Although limited evidence supports this use, some physicians also prescribe spironolactone for female pattern baldness.


Cyproterone was among the earliest testosterone blockers developed. Healthcare providers prescribe it in conjunction with other medications to treat women with PCOS. It has the potential to decrease testosterone levels and reduce the production of acne-causing oils.

Additionally, doctors might administer cyproterone to dampen masculine traits in transgender women. However, due to its side effects, it is generally not the preferred option. Currently, cyproterone is unavailable in the United States.

What are the side effects of testosterone blockers?

Depending on the dosage and specific type of testosterone blocker you take, you may experience a variety of side effects.

Some possible side effects are:

  • Decreased libido (i.e., low sex drive)
  • Liver injury (e.g., hepatitis)
  • Erectile dysfunction
  • Increased risk of depression
  • Elevated liver enzymes
  • Reduced facial and body hair
  • Diarrhea
  • Breast tenderness
  • Hot flashes
  • Menstrual irregularity
  • Skin rash
  • Testosterone blocker resistance, where the medication ceases to be effective

Your doctor can assist you in selecting a testosterone blocker that best aligns with your needs.

Takeaway message

Testosterone blockers are effective medications that have several uses in the medical field. These drugs have antitumor properties and can also help individuals during their gender-transitioning journey. Pay attention to the side effects of testosterone blockers before taking them.

We hope that this article managed to highlight the common uses and types of testosterone blockers, as well as their potential side effects.

If you have any questions, concerns, or personal experiences with testosterone blockers, please feel free to share your thoughts in the comment section below. You can also contact us via this link for a private conversation.

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