- Design
- Randomised, double-blind, placebo-controlled trial, 24 weeks plus open-label extension
- Population
- 46 transgender people on testosterone with mild androgenetic alopecia
- Primary outcome
- Change in midfrontal and vertex target-area hair count
- Effect
- Midfrontal +15.7 hairs/cm² vs placebo; vertex no difference at 24 weeks
Treatments that block 5-alpha-reductase can blunt masculinisation, which limits options for transgender people with androgenetic alopecia on testosterone. This Australian double-blind trial randomised 46 participants with mild hair loss to sublingual minoxidil 1.35 mg twice daily or placebo for 24 weeks, followed by open-label 2.5 mg twice daily.
At 24 weeks, midfrontal hair count rose by 15.7 hairs/cm² more with minoxidil than placebo; the vertex did not differ. In the open-label phase, vertex counts rose by 37.9 hairs/cm² from baseline by week 48. Minoxidil did not alter testosterone levels, and there were no serious adverse events.
The trial is small and only one of two co-primary end points was met in the blinded phase. It nevertheless supports low-dose systemic minoxidil as an option that does not interfere with gender-affirming therapy.
- Offer low-dose minoxidil rather than 5-alpha-reductase inhibitors when preserving masculinisation matters
- Check blood pressure and ask about oedema and palpitations when starting systemic minoxidil
- Warn about unwanted facial and body hair growth
- Allow six months before judging response
Why it matters
It gives an option that does not work against gender-affirming treatment.
Don't overread it
Only the midfrontal co-primary end point was met; the vertex gain comes from the uncontrolled open-label phase.
The statistics, in plain English
The trial had two co-primary end points and met one. Changes within the open-label phase lack a placebo comparison, so they may overstate the effect.
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