Hormone replacement therapy (HRT) can have significant effects on hair growth in transgender women. The hormones used in masculinizing or feminizing hormone therapy, namely testosterone and estrogen, play key roles in hair production and maintenance. When hormone levels are altered through HRT, changes in hair growth patterns often follow.
For transgender women undergoing feminizing HRT, anti-androgens like spironolactone are commonly used to suppress testosterone levels. Lower testosterone reduces stimulatory effects on hair follicles, leading to slowed growth of body and facial hair. However, estrogen therapy is more directly linked to changes in scalp hair.
Estrogen exerts growth-promoting effects on scalp hair follicles. During puberty in natal females, rising estrogen levels trigger growth of scalp hair that is fuller, longer, and faster-growing. Estrogen likely supports scalp hair growth through several mechanisms:
- Prolonging the growth phase of hair follicles
- Increasing hair follicle size
- Stimulating faster hair growth cycles
- Blocking testosterone conversion into DHT, a hormone that miniaturizes hair follicles
These estrogen-mediated effects can translate into substantial improvements in scalp hair growth and quality during feminizing HRT in transgender women. Documented effects include:
- Scalp hair regrowth in areas of male pattern baldness
- Thicker, fuller scalp hair overall
- Softer, less dry hair texture
- Longer scalp hair due to extended growth phase
The degree of new scalp hair growth depends on the extent of prior balding and individual response to estrogen therapy. However, the majority of transgender women on feminizing HRT report significant scalp hair regrowth, even those who were nearly bald before beginning therapy.
When initiated prior to extensive balding, feminizing HRT can often halt male pattern baldness completely. In addition to scalp hair changes, estrogen reduces hair growth on other areas of the body deemed undesirable by transgender women, such as the face, back, shoulders, and arms. This body hair thinning develops gradually but can ultimately reduce density by 30-50%.
For transgender men on masculinizing HRT, testosterone therapy stimulates increased growth of both facial and body hair. The impacts develop in a masculinizing pattern based on genetic predispositions. Effects of testosterone include:
- Increased growth rate, thickness and darkness of facial hair
- New facial hair growth that was previously absent
- Increased body hair density on the arms, legs, chest, back, and abdomen
- Scalp hair thinning, similar to male pattern baldness (varies greatly)
These effects arise due to testosterone's stimulatory effects on hair follicles, making them larger, darker, and capable of faster regeneration. Testosterone may also prolong the growth phase of hair follicles in some areas while shortening it on the scalp.
The timing and degree of masculinizing body and facial hair growth depends largely on genetics, age at starting HRT, and dosage/formulation of testosterone therapy. However, most transgender men can expect significant masculinization of hair growth patterns that allow them to align more closely with their male gender identity.
In summary, HRT in transgender individuals aims to induce secondary sex characteristics reflecting their gender identity. The high sensitivity of hair follicles to sex hormones means that dramatic changes in hair growth commonly occur during transition. While individual responses vary, feminizing HRT reliably stimulates scalp hair regrowth in transgender women, while masculinizing HRT reliably increases facial and body hair growth in transgender men.
If you are considering medical transition, the providers at The Hormone Hub Hormone Therapy Clinic can help you understand the likely timing and extent of hormone-induced changes in hair growth. We develop customized transition plans with respectful, compassionate care. Contact us today for a consultation, and take the first steps towards becoming your true self.
