Hormones are chemicals produced by our bodies that regulate our biological sex. The major hormone for men is testosterone while the major one for women is estrogen. We can reproduce these hormones in the laboratory. The goal of hormone therapy for transgendered people is to reduce the natural hormone your body produces and to replace those hormones with those of your “chosen” gender.
In males, the taking of female hormones produces the experience similar to puberty for a girl (except for the beginning of menopause). Body fat gets redistributed, there’s a decrease in muscle mass, his appearance looks more feminine, his breasts begin to grow, his sexual drive is decreased, his skin gets softened, etc. These processes usually take up to 3 years to complete1. He’ll be on hormones the rest of his life.
In females, the taking pf male hormones produces the experience similar to puberty for a boy. She feels a sexual drive increase, more oily/acne skin, facial and body hair growth, increased muscle mass, fat redistribution to look more masculine, deepening of her voice, she stops having periods, clitoral enlargement, vaginal atrophy, etc. These processes can take up to 5 years to complete1. She’ll be on hormones the rest of her life.
Not every transgendered person wants to do hormone therapy. It takes a long time to complete, they have to be on it for the rest of their lives and there are risks associated with it, even though most doctors say it is relatively safe. There’s little data on the long term use of these hormones. Risks for cancer may become more apparent with long term use and as the person ages2. While some effects of hormone therapy are reversible, some are not. In female to male hormone therapy, voice change, facial hair growth and male pattern hair loss are not reversible3. In male to female hormone therapy, breast growth along with development of the nipple-aerolar complex are permanent4.
1…Wylie C. Hembree, “Endocrine Treatment of Transsexual Persons; An Endocrine Society Clinical Practice Guideline”, Journal of Clinical Endocrinology and Metabolism 94, no.9 (2009):3145
2…Louis J. Gooren, “Hormone Treatment of Adult Transgender People” in Principles of Transgender Medicine and Surgery, 2nd ed. (New York: Rutledge,2016), ‘Care of Transsexual Persons’ 1254.
3…Marshall Dahl, “Physical Aspects of Transgender Endocrine Therapy”, International Journal of Transgenderism 9, nos.3-4 (2006):118
4…Marshall Dahl, above, 113 & 114