What Are Cross Sex Hormones and What Are Their Effects?

Cross-sex hormones are medications used by transgender and gender-diverse individuals to induce physical changes that align their bodies with their gender identity. This treatment is a form of gender-affirming care undertaken to help an individual feel more congruent in their body. For many, this is a significant step in their gender transition that aims to alleviate the distress from a mismatch between one’s body and identity.

Understanding Cross-Sex Hormones

Hormone therapy promotes the development of secondary sex characteristics that align with an individual’s gender identity. The treatment is categorized into two types: feminizing and masculinizing therapy. Specific medications and dosages are tailored to the individual’s goals and health profile.

Feminizing regimens use a combination of estrogens and anti-androgens to induce female secondary sex characteristics. Estrogens, like estradiol, are the primary hormones for these changes. Anti-androgens, such as spironolactone, block the effects of testosterone, and progestogens are sometimes included.

Masculinizing therapy uses testosterone to promote male secondary sex characteristics, administered via injections, gels, or patches. Unlike feminizing therapy, an additional medication to block natal hormones is not required. Therapeutic doses of testosterone are sufficient to suppress estrogen production.

These hormones function by interacting with specific receptors in cells throughout the body. When the hormones bind to these receptors, they signal the body to alter its functions and develop characteristics associated with the affirmed gender. This process gradually reshapes the body’s physical appearance and can also influence emotional states.

Effects of Feminizing Hormones

The physical changes from feminizing therapy unfold over months and years, with the timeline and results depending on factors like age, genetics, and the specific hormone regimen. It is important to note that feminizing hormones do not change a person’s voice pitch.

Common physical changes include:

• Breast development, which begins within three to six months and can take two to three years for its full effect.
• Body fat redistribution, with more accumulation around the hips and thighs.
• Softer and less oily skin, a change that can start within three to six months.
• A decrease in muscle mass and a slowing or cessation of scalp hair loss.
• Decreased testicular size and reduced sperm production, which can impact fertility.
• Decreased libido and frequency of spontaneous erections, often beginning within one to three months.

Effects of Masculinizing Hormones

The physical changes from masculinizing therapy develop progressively, with a timeline that differs based on genetics and age. Some changes, such as voice deepening and facial hair growth, are irreversible even if testosterone is discontinued.

Common physical changes include:

• Deepening of the voice, which can begin within the first year and take one to two years for its full effect.
• Growth of facial and body hair, starting within three to six months and developing over several years.
• Cessation of menstruation, which occurs within two to six months of beginning therapy.
• Redistribution of body fat and an increase in muscle mass and strength.
• Enlargement of the clitoris.
• Oiler skin, which can potentially lead to acne.
• Male pattern baldness, the extent of which is influenced by genetic predisposition.

Navigating Hormone Therapy Safely

Hormone therapy requires medical supervision from a qualified healthcare provider experienced in transgender health. The process begins with an initial assessment to discuss health history, goals, and the risks and benefits of treatment. This ensures the individual can make an informed decision.

Ongoing monitoring is a standard part of hormone therapy. This involves regular appointments and blood tests to check hormone levels and overall health. These tests help the provider adjust dosages as needed and screen for potential side effects like changes in liver function, cholesterol, or blood counts.

There are potential health considerations associated with both hormone types. Feminizing hormones can increase the risk of blood clots, and may cause issues with the gallbladder or elevated prolactin levels. Masculinizing hormones can lead to an increase in red blood cell count (polycythemia) and may affect liver function or contribute to sleep apnea.

A significant consideration is the impact on fertility, as cross-sex hormones can permanently reduce or eliminate the ability to have biological children. For those who may want biological children, it is advisable to discuss fertility preservation options, such as sperm or egg banking, before starting hormone therapy.