Two recent letters to the editor in the Journal of the American Academy of Dermatology shed light on the degree of body hair growth that trans men can expect from testosterone, as well as the various factors implicated in the development of acne in this population. The first, by Motosko et al. (2019), examined body hair growth patterns in 90 trans men compared to 30 cis men and 30 cis women. The authors observed that among trans men, those who were taking testosterone scored higher on a measure of body hair growth compared to cis women, but lower than cis men:
Transgender men taking testosterone had significantly higher Ferriman-Gallwey scores (median 5 [IQR 3-9], P < .001) than cisgender women and transgender men not on testosterone; however, their scores remained lower than those of cisgender men (median 10.5 [IQR 7.25-12], P < .001) (Fig 2).
Moreover, having taken testosterone for a longer duration correlated with greater body hair growth, and the authors found that testosterone “showed the greatest effect on hair growth on the lower abdomen”:
Notably, in this sample, 52% of trans men on testosterone experienced chest acne compared to only 6.7% of cis men. Park, Carter, & Larson (2019) explored this phenomenon further, looking into particular factors associated with the presence of acne in a sample of 55 trans men who had taken testosterone for at least two years and had no history of acne prior to treatment. These patients had a median testosterone level of 630 ng/dL, and the authors found that levels higher than this were significantly associated with the development of acne. Additionally, smoking and a higher body mass index were linked to a greater likelihood of acne. The likelihood of having experienced acne increased substantially during the first two years of taking testosterone:
The authors further note that management of undesired acne may be possible through alteration of testosterone dosage:
Nakamura et al reported that during the first 6 months only, the most commonly desired virilization effects were dose dependent. If a transgender man begins to develop acne, it may be possible to personalize his testosterone therapy depending on transition goals, priorities, risk factors, and other comorbidities.
