AT A GLANCE

A new randomized clinical trial compared two injection techniques of botulinum toxin A for androgenetic alopecia and found no significant benefit on hair density or terminal-to-vellus hair ratio, challenging the hypothesis of its therapeutic role in male pattern hair loss.

Interest in botulinum toxin A (BoNT-A) as a novel approach to androgenetic alopecia (AGA) has grown in recent years, based on the proposed mechanism of improving scalp perfusion and reducing perifollicular inflammation. This randomized, controlled six-month clinical trial rigorously evaluated the efficacy of BoNT-A monotherapy using two administration protocols—subcutaneous only versus combined subcutaneous and intramuscular injections—in treatment-naïve men with moderate AGA (Hamilton-Norwood III–V).

Despite these theoretical advantages, the study found no significant improvements in key trichoscopic parameters, including hair density or vellus-to-terminal hair ratio, in either treatment group after six months. Interestingly, both regimens were associated with a reduction in frontal hair thickness, and combined injection was linked to a significant decrease in terminal hair count, suggesting a potential adverse or neutral effect rather than a therapeutic one. No meaningful differences were observed in the occipital control region.

These findings underscore the importance of controlled clinical evaluation before adopting neuromodulatory agents for hair restoration and suggest that BoNT-A, in its current dosing and administration formats, should not be considered an effective standalone therapy for AGA. Further research may clarify whether it has any adjunctive benefit alongside established treatments such as finasteride or minoxidil.

Reference: Lima-Galindo AA, Ocampo-Garza SS, Ocampo-Candiani J, et al. Subcutaneous Versus Combined Subcutaneous and Intramuscular Botulinum Toxin for Androgenetic Alopecia: A Randomized Clinical Trial. Actas Dermosifiliogr. 2025 Oct;116(9):T959-T966. English, Spanish. doi: 10.1016/j.ad.2025.07.020. Epub 2025 Jul 21. PMID: 40701233.

DRUG AT A GLANCE

Botulinum Toxin Type A (BoNT-A) is a neurotoxin that inhibits acetylcholine release at neuromuscular junctions, leading to temporary muscle paralysis. It is widely used in aesthetic and neurologic medicine for conditions such as facial rhytides, hyperhidrosis, and dystonias. In dermatology, BoNT-A has been hypothesized to improve scalp circulation and reduce local inflammation, offering a potential novel mechanism for treating androgenetic alopecia. However, current evidence—including this randomized trial—does not support its efficacy as a monotherapy for hair regrowth.