Table of ContentsView AllTable of ContentsWhat Hormones DoHow They WorkTreatment OptionsOrchiectomy SurgeryAlternative Androgen Blockers
Table of ContentsView All
View All
Table of Contents
What Hormones Do
How They Work
Treatment Options
Orchiectomy Surgery
Alternative Androgen Blockers
Testosterone blockers, also known as anti-androgen drugs, are commonly prescribed totransgender womento block the effects oftestosterone, the primary male sex hormone. By doing so, the drug can reduce some of the characteristic male traits (like facial hair and male-pattern baldness).
Testosterone blockers are taken alongsideestrogen, the primary female sex hormone. In addition to promoting characteristic female traits (like breasts and pelvic bone structure), estrogen also indirectly reduces testosterone levels in the bloodstream.
The article explains how testosterone blockers work and what drug options are available to transfeminine individuals. It also explains howorchiectomy, or the surgical removal of thetestes (testicles), can eliminate the need for testosterone blockers.
Victoria Holguin / Getty Images
Hormones and Gender Presentation
All people produce estrogen and testosterone, albeit at different levels. During puberty, different developmental changes take place depending on whether testosterone or estrogen is the dominant hormone.
People Assigned Female at Birth
Testosterone is also produced in smaller amounts in the ovaries as well as theadrenal glands. It plays an important role in bone health, vaginal lubrication, andlibido(sex drive).
People Assigned Male at Birth
In people assigned male at birth, testosterone is the hormone that dominates from puberty onward. Produced mainly in the testes, testosterone helps spur secondary male characteristics like facial hair, an enlarged voice box (Adam’s apple), and increased muscle and bone mass.
Estrogen is also produced in smaller amounts in the testes. It plays an important role in the development ofspermas well as the ability to achieve anerection(hardened penis).
Effects of Testosterone Blockers
Often, the first step in a medical gender transition is to begin hormone therapy, also known asgender-affirming hormone therapy.
For transgender women, this involves not only the use of estrogen (in the form of estradiol) but also the use of a testosterone blocker. This is because testosterone acts much more strongly than estrogen does.
When people are exposed to both hormones, the effects of testosterone will almost invariably surpass the effects of estrogen. This can make the process of feminization more challenging for transfeminine people.
In short, they can’t just take estrogen to develop more feminine characteristics. They must also reduce their natural testosterone production or block the effects of testosterone. This is where testosterone blockers come in.
What Drugs Are Used as Testosterone Blockers?
There are several drugs commonly used as a testosterone blockers in transgender women.
Aldactone (Spironolactone)
Aldactone (spironolactone) is the most commonly used anti-androgen in the United States. It is a type of steroid that not only works as a testosterone blocker but is also used as adiuretic(“water pill”) to treat high blood pressure and heart failure.
Aldactone blocks the effects of the hormone aldosterone (which regulates fluid levels) while reducing testosterone levels in the body. It is this latter effect that makes Aldactone effective in treating symptoms likeacneandhirsutism(excessive facial hair) in females withpolycystic ovary syndrome (PCOS).
Gonadotropin-Releasing Hormone (GnRH) Agonists
Gonadotropin-releasing hormone (GnRH) agonistsblock the release of a hormone called GnRH that directs testosterone production. Without ample GnRH, testosterone levels in transgender youth will drop, preventing the development of certain secondary male sex characteristics.
These drugs may also be used to suppress testosterone production in transgender adults. Other uses include treating hormone-sensitive prostate cancers and benignuterine fibroids.
Supprelin LA (histrelin) is sometimes used as a puberty blocker for transgender youth.Supprelin LA is available as a 12-month subcutaneous implant. The implant is a narrow 1-1/2" tube that is inserted beneath the skin of the upper arm. Common side effects include localized pain, bruising, and headaches.
Supprelin LA (or any other form of histrelin) is not commonly used as a testosterone blocker in transgender adults.
Lupron (leuprolide) is a GnRH agonist similarly used to suppress puberty in transgender youths. Transgender adults may also use it to reduce testosterone levels.
What About Cyprostat?Cyprostat (cyproterone acetate) is available as a testosterone blocker for transgender women in Europe. Some research suggests that it may be more effective at lowering testosterone levels than spironolactone. Even so, it is not approved for use in the United States due to concerns about liver toxicity and liver cancer.
What About Cyprostat?
Cyprostat (cyproterone acetate) is available as a testosterone blocker for transgender women in Europe. Some research suggests that it may be more effective at lowering testosterone levels than spironolactone. Even so, it is not approved for use in the United States due to concerns about liver toxicity and liver cancer.
Orchiectomy, or the surgical removal of the testes, is an effective way to reduce testosterone in transgender women. Unlike anti-androgen drugs, its effects are permanent.
Orchiectomy can often eliminate the need for testosterone blockers, although some transfeminine individuals may need to use drugs like finasteride to combat ongoing concerns like male-pattern hair loss.
Transgender women who undergo orchiectomy may also be able to take lower doses of estrogen. This reduces the risk of long-term side effects like high cholesterol, heart problems, and blood clots.
Orchiectomy is usually not used until a person is very stable in theirgender identity. Even so, orchiectomy may be an early option for people who cannot take testosterone blockers for any reason (including a drug allergy or having a kidney or liver disease).
Orchiectomy is sometimes done as part ofvaginoplasty surgery(the surgical construction of a vagina), although many transgender women have no interest in pursuing vaginoplasty.
Insurance Coverage for Gender Surgery
A physician may sometimes consider adding these to a person’s feminization therapy but they are not part of the standard of care.
Finasteride
Finasterideis a drug widely used to treat male-pattern hair loss (under the brand name Propecia) andenlarged prostate(under the brand name Proscar).
Finasteride belongs to a class of drugs called 5-alpha reductase inhibitors that block the conversion of testosterone into the more bioactive form of testosterone calleddihydrotestosterone (DHT).
Finasteride can be prescribed at a 5-mg daily dose (the same as Proscar) but may increase the risk of side effects, including low libido and swelling of the hands and feet.
In transfeminine individuals, finasteride is generally considered an alternative to Aldactone.
Avodart (Dutasteride)
Avodart (dutasteride) is a 5-alpha reductase inhibitor also used to treat enlarged prostate and male-pattern baldness. As a testosterone blocker, Avodart may offer more dramatic feminizing effects than finasteride.
As with finasteride, Avodart is a good choice for people who cannot tolerate or use Aldactone. Both can also be used in transgender women who have undergone orchiectomy but still have secondary male features like hair loss.
Flutamide
Flutamideis a type of anti-androgen used to treat hormone-sensitiveprostate cancer. The same mechanism of action may be effective at reducing the effects of testosterone in transfeminine individuals.
Flutamide binds to testosterone receptors in other cells as well. When used for gender-affirming therapy, Flutamide can reduce the masculinizing effects of testosterone in transgender women.
Summary
Testosterone blockers, also known as anti-androgen drugs, are used to block the masculinizing effects of testosterone in transgender women. Aldactone (spironolactone) is most commonly used, but other drugs like Propecia (finasteride), Avodart (dutasteride), and flutamide may also be prescribed.
For transgender youth, a subcutaneous implant called Supprelin LA (histrelin) can help prevent the development of certain secondary male characteristics during puberty.
Orchiectomy (the surgical removal of the testicles) is a permanent solution that may eliminate the need for testosterone blockers. It may also reduce how much estrogen you need to take as part of gender-affirming therapy.
What to Know About Estrogen Therapy in Transgender Women
6 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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