Masculinizing 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 masculinizing 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.

Masculinizing 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 masculinizing hormone therapy if you:

• Are pregnant.
• Have a hormone-sensitive cancer, such as breast cancer.
• Have problems with blood clots, such as when a blood clot forms in a deep vein, a condition called deep vein thrombosis, or 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 masculinizing 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 and will not happen in your body as a result of masculinizing hormone therapy.

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

• Weight gain.
• Acne.
• Developing male-pattern baldness.
• Sleep apnea.
• A rise in low-density lipoprotein (LDL), the "bad" cholesterol, and a fall in high-density lipoprotein (HDL), the "good" cholesterol. This may raise the risk of heart problems.
• High blood pressure.
• Making too many red blood cells — a condition called polycythemia.
• Type 2 diabetes.
• Blood clots in a deep vein or in the lungs.
• Infertility.
• Drying and thinning of the lining of the vagina.
• Pelvic pain.
• Discomfort in the clitoris.

Evidence suggests that people who have masculinizing hormone therapy don't have a higher risk of breast cancer, endometrial cancer or heart disease when compared to cisgender women — women whose gender identity aligns with their sex assigned at birth.

It's unclear whether masculinizing hormone therapy raises the risk of ovarian and uterine cancer. More research is needed.

To minimize risk, the goal for people taking masculinizing hormone therapy is to keep hormone levels in the range that's typical for cisgender men — men whose gender identity aligns with their sex assigned at birth.

Fertility

Masculinizing 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 ovaries and uterus might not recover enough for you to become pregnant without infertility treatment.

If you want to have biological children, talk to your healthcare professional about your choices. They may include:

• Egg freezing. This procedure also is called mature oocyte cryopreservation. Egg freezing has multiple steps that involve triggering ovulation, retrieving the eggs and then freezing them.
• Embryo freezing. This process also is known as embryo cryopreservation. If you want to freeze embryos, you'll need to have the eggs fertilized before they are frozen.
• Ovarian tissue cryopreservation. With this procedure, ovarian tissue is removed, frozen, and later thawed and reimplanted.

Although testosterone might limit your fertility, you still can become pregnant if you have your uterus and ovaries and you have sex with a person who produces sperm. If you want to avoid pregnancy, always use birth control. Talk with your healthcare professional about the form of birth control that's best for you.

Before you start masculinizing 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 birth control, fertility and sexual function.

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 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 masculinizing 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 you understand what will happen and get answers to any questions you may have before you begin hormone therapy.

Masculinizing hormone therapy typically begins by taking testosterone. A low dose of testosterone is prescribed. Then the dose is slowly increased over time. Testosterone usually is given through a shot, also called an injection, or through a gel or patch applied to the skin. Other forms of testosterone that may be appropriate for some people include testosterone pellets placed under the skin, a prolonged action injection and an oral capsule taken twice a day.

The testosterone that's used for masculinizing hormone therapy is identical to the hormone that the testicles and ovaries make naturally. Don't use synthetic androgens, such as oral methyl testosterone or anabolic steroids. They can harm your liver and cannot be accurately monitored.

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

• Menstruation stops. This happens within 2 to 6 months of starting treatment.
• Voice deepens. This begins 3 to 12 months after you start treatment. The full effect happens within 1 to 2 years.
• Facial and body hair grows. This begins 3 to 6 months after treatment starts. The full effect happens within 3 to 5 years.
• Body fat is redistributed. This begins within 3 to 6 months. The full effect happens within 2 to 5 years.
• Clitoris become larger, and the vaginal lining thins and become drier. This begins 3 to 12 months after treatment starts. The full effect happens in about 1 to 2 years.
• Muscle mass and strength increases. This begins within 6 to 12 months. The full effect happens within 2 to 5 years.

If menstrual bleeding doesn't stop after you've taken testosterone for several months, your healthcare professional might suggest that you take medicine to stop it.

Some of the physical changes caused by masculinizing hormone therapy can be reversed if you stop taking testosterone. Others, such as a deeper voice, a larger clitoris, scalp hair loss, and more body and facial hair, cannot be reversed.

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

• Keep track of your physical changes.
• Monitor your hormone levels. Over time, your dose of testosterone 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 lab 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.
• Cervical cancer screening. This should be done according to cervical cancer screening recommendations for cisgender women your age. Be aware that masculinizing hormone therapy can cause your cervical tissues to thin. That can look like a condition called cervical dysplasia in which unusual cells are found on the surface of the cervix. If you have questions or concerns about this, talk to your healthcare professional.
• Monitoring bone health. You should have bone density assessments according to the recommendations for cisgender men your age. You may need to take calcium and vitamin D supplements for bone health.