Feminizing hormone therapy is used to make physical changes in the body that are caused by female hormones during puberty. Those changes are called secondary sex characteristics. This hormone therapy can help better align the body with a person's gender identity. Feminizing hormone therapy also is called gender-affirming hormone therapy.

Feminizing hormone therapy involves taking medicine to block the action of the hormone testosterone. It also includes taking the hormone estrogen. Estrogen lowers the amount of testosterone the body makes. It also triggers the development of feminine secondary sex characteristics. Feminizing hormone therapy can be done alone or along with feminizing surgery.

Feminizing hormone therapy can affect fertility and sexual function, and it might lead to health problems. Talk with your healthcare professional about the risks and benefits.

Feminizing hormone therapy is used to change the body's hormone levels. Those hormone changes trigger physical changes that help better align the body with a person's gender identity.

In some cases, people seeking feminizing hormone therapy experience discomfort or distress because their gender identity differs from their sex assigned at birth or from their sex-related physical characteristics. This condition is called gender dysphoria.

Feminizing hormone therapy can:

• Improve psychological and social well-being.
• Ease psychological and emotional distress related to gender.
• Improve satisfaction with sex.
• Improve quality of life.

Your healthcare professional might advise against feminizing hormone therapy if you:

• Have a hormone-sensitive cancer, such as prostate cancer.
• Have problems with blood clots, such as when a blood clot forms in a deep vein, a condition called deep vein thrombosis, or a there's a blockage in one of the pulmonary arteries of the lungs, called a pulmonary embolism.
• Have significant medical conditions that haven't been addressed.
• Have behavioral health conditions that haven't been addressed.
• Have a condition that limits your ability to give your informed consent.

Research has found that feminizing hormone therapy can be safe and effective when delivered by a healthcare professional with expertise in transgender care. Talk to a member of your care team about questions or concerns you have regarding the changes that will or will not happen in your body as a result of feminizing hormone therapy.

Feminizing hormone therapy may lead to other health conditions called complications. Complications of feminizing hormone therapy can include:

• Blood clots in a deep vein or in the lungs.
• Stroke.
• Heart problems.
• High levels of triglycerides, a type of fat, in the blood.
• High levels of potassium in the blood.
• High levels of the hormone prolactin in the blood.
• Nipple discharge.
• Weight gain.
• Infertility.
• High blood pressure.
• Type 2 diabetes.

Evidence suggests that people who take feminizing hormone therapy may have a higher risk of breast cancer when compared to cisgender men — men whose gender identity aligns with their sex assigned at birth. But the risk is not greater than that of cisgender women — women whose gender identity aligns with their sex assigned at birth.

To minimize risk, the goal for people taking feminizing hormone therapy is to keep hormone levels in the range that's typical for cisgender women.

Fertility

Feminizing hormone therapy may limit fertility. If possible, it's best to make decisions about fertility before starting treatment. The risk of permanent infertility increases with long-term use of hormones. That is particularly true if hormone therapy is started before puberty begins. Even after stopping hormone therapy, the testicles might not recover enough to ensure conception without infertility treatment.

If you want to have biological children, talk to your healthcare professional about freezing sperm before you start feminizing hormone therapy. That procedure is called sperm cryopreservation.

Before you start feminizing hormone therapy, your healthcare professional assesses your health. This helps address any medical conditions that might affect your treatment. The evaluation may include:

• A review of your personal and family medical history.
• A physical exam.
• Lab tests.
• A review of your vaccinations.
• Screening tests for some conditions and diseases.
• Identification and management, if needed, of tobacco use, drug use, alcohol use disorder, HIV or other sexually transmitted infections.
• Discussion about sperm freezing and fertility.

You also might have a behavioral health evaluation by a healthcare professional with expertise in transgender health. The evaluation may assess:

• Gender identity.
• Gender dysphoria.
• Mental health concerns.
• Sexual health concerns.
• The impact of gender identity at work, at school, at home and in social settings.
• Risky behaviors, such as substance use or use of unapproved silicone injections, hormone therapy or supplements.
• Support from family, friends and caregivers.
• Your goals and expectations of treatment.
• Care planning and follow-up care.

People younger than age 18, along with a parent or guardian, should see a healthcare professional and a behavioral health professional with expertise in pediatric transgender health to talk about the risks and benefits of hormone therapy and gender transitioning in that age group.

You should start feminizing hormone therapy only after you've talked about the risks and benefits, as well as all treatment options available to you, with a healthcare professional who has expertise in transgender care. Make sure that you understand what will happen and get answers to any questions you may have before you begin hormone therapy.

Feminizing hormone therapy typically begins by taking the medicine spironolactone (Aldactone). It blocks male sex hormone receptors — also called androgen receptors. This slows or stops changes in the body that usually happen due to testosterone.

About 4 to 8 weeks after you start taking spironolactone, you begin taking estrogen. This lowers the amount of testosterone the body makes. And it triggers physical changes in the body that are caused by female hormones during puberty.

Estrogen can be taken several ways. They include a pill and a shot. There also are several forms of estrogen that are applied to the skin, including a cream, gel, spray and patch.

It is best not to take estrogen as a pill if you have a personal or family history of blood clots in a deep vein or in the lungs, a condition called venous thrombosis.

Another choice for feminizing hormone therapy is to take gonadotropin-releasing hormone (Gn-RH) analogs. They lower the amount of testosterone that the body makes and might allow you to take lower doses of estrogen without taking spironolactone. The disadvantage is that Gn-RH analogs usually are more expensive.

After you begin feminizing hormone therapy, you'll notice the following changes in your body over time:

• Fewer erections and a decrease in ejaculation. This begins 1 to 3 months after treatment starts. The full effect happens within 3 to 6 months.
• Less interest in sex. This also is called decreased libido. It begins 1 to 3 months after treatment starts. The full effect happens within 1 to 2 years.
• Slower scalp hair loss. This begins 1 to 3 months after treatment begins. The full effect happens within 1 to 2 years.
• Breast development. This begins 3 to 6 months after treatment starts. The full effect happens within 2 to 3 years.
• Softer, less oily skin. This begins 3 to 6 months after treatment starts. That's also when the full effect happens.
• Smaller testicles. This also is called testicular atrophy. It begins 3 to 6 months after the start of treatment. The full effect happens within 2 to 3 years.
• Less muscle mass. This begins 3 to 6 months after treatment starts. The full effect happens within 1 to 2 years.
• More body fat. This begins 3 to 6 months after treatment starts. The full effect happens within 2 to 5 years.
• Less facial and body hair growth. This begins 6 to 12 months after treatment starts. The full effect happens within three years.

Some of the physical changes caused by feminizing hormone therapy can be reversed if you stop taking it. Others, such as breast development, cannot be reversed.

While on feminizing hormone therapy, you meet regularly with your healthcare professional to:

• Keep track of your physical changes.
• Monitor your hormone levels. Over time, your hormone dose may need to change to make sure you are taking the lowest dose necessary to achieve and then maintain the physical effects that you want.
• Have blood tests to check for changes in your cholesterol, potassium, blood sugar, blood count, and liver enzymes that could be caused by hormone therapy.
• Monitor your behavioral health.

You also need routine preventive care. Depending on your situation, this may include:

• Breast cancer screening. This should be done according to breast cancer screening recommendations for cisgender women your age.
• Prostate cancer screening. This should be done according to prostate cancer screening recommendations for cisgender men your age.
• Monitoring bone health. You should have bone density assessments according to the recommendations for cisgender women your age. You may need to take calcium and vitamin D supplements for bone health.