Journal of the American Academy of Dermatology: July 2024

Male androgenetic alopecia (AGA), or male pattern hair loss, is characterized by gradual thinning of hair on the vertex of the scalp and recession of the frontal hairline. 

FDA-approved therapies are restricted to topical minoxidil and oral finasteride. Effective non–FDA-approved treatments include, but are not limited to, low-dose oral minoxidil, topical finasteride or dutasteride, latanoprost, and platelet-rich plasma injections.

The use of botulinum toxin (BT) has emerged as a potential treatment for AGA in recent years, hypothesized to work by relaxing the scalp muscles, increasing blood flow, reducing tissue dihydrotestosterone levels, and modulating fibroblast activity.

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This randomized placebo-controlled trial assessed the efficacy of treatment with botulinum toxin for male androgenetic alopecia. The study enrolled only 13 men, and they served as their own controls.

Half of the scalp was injected with 25 IU of botulinum toxin at weeks 0 and 12, and the other half of the scalp was injected with an equal volume of normal saline in mirrored injection sites. Using clinical photography and TrichoLAB hair-to-hair matching technology, the authors found no statistically significant difference between the two sides of the scalp in terms of hair density.

This study suggests that botulinum toxin injection is not effective for the treatment of androgenetic alopecia in males. Larger randomized controlled studies are needed to confirm this finding.