The trial from Brazil enrolled 100 men aged 25 to 55 years (average age 39.5) with moderate to severe AGA, classified as Norwood-Hamilton stage 3V to 5V. After 24 weeks, 92 participants completed the study, split evenly between the 2.5 mg and 5 mg daily groups.
At baseline, the 2 groups showed similar hair profiles where the 2.5 mg group started with a mean non-vellus (thicker, terminal) hair density of 144.7 hairs per square centimeter, and the 5 mg group had 146.1 hairs per square centimeter. Total hair density (both terminal and finer hairs) was slightly higher in the lower-dose group at 214.7 hairs/cm² when compared to 194.4 hairs/cm² in the higher-dose group.
The primary goal was to measure changes in non-vellus hair density at the vertex, the crown area often most affected by male pattern baldness. Secondary measures included total hair density, dermatologist-assessed global photographs, self-reported improvement, and the frequency of side effects.
At the 24-week mark, non-vellus hair density increased in both, with no statistically significant difference: the mean difference between the two doses was just 0.9 hairs/cm² (P = .403). Total hair density changes also mirrored each other closely, with only a slight, non-significant advantage in the higher dose group (mean difference, 3.6 hairs/cm²; P = .078).
Independent dermatologists who assessed the clinical photographs rated improvement in 64% of men on 2.5 mg and 62% on 5 mg, again showing no meaningful gap (P = .386). However, men themselves perceived more benefit at the higher dose where 92% of participants taking 5 mg reported improvement when compared to 84% in the 2.5 mg group (P = .009).
Adverse effects like pedal edema and dizziness were significantly more common in the 5 mg group (P = .024). Also, no substantial differences were observed in blood pressure or heart rate between the groups, addressing concerns about systemic cardiovascular risks associated with oral minoxidil.
Source:
Fonseca, L. P. C., Miot, H. A., Chaves, C. R. P., & Ramos, P. M. (2025). Oral minoxidil 2.5mg vs 5mg for male androgenetic alopecia: A double-blind randomized clinical trial. Journal of the American Academy of Dermatology. https://doi.org/10.1016/j.jaad.2025.09.031
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