Outcomes of Treatment With Botulinum Toxin in Males With Androgenetic Alopecia

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. Although AGA can significantly affect mental health and the quality of life, treatment options are limited. FDA-approved therapies are restricted to topical minoxidil and oral finasteride.¹ 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.¹

Additional treatments for AGA are sorely needed, given the number of patients affected by this form of hair loss. 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. As BT therapy can be costly and requires patients to pay for the treatment out of pocket, we applaud these authors for investigating BT therapy as a treatment for AGA in this small, but well-designed, study.

This article assessed the efficacy of BT therapy in patients with male AGA through a randomized, triple-blind, placebo-controlled clinical trial. The study tested BT therapy for treating male AGA in 13 participants, and each participant served as his own control. Over 24 weeks, BT was injected into one side of the scalp and saline into the other. Notably, no significant differences were found in hair density or quality between the BT- and saline-treated sides. Overall, BT did not show any benefit for hair regrowth in men with AGA. This evidence is important to help guide therapy recommendations for patients with AGA.

Reference

1. Devjani S, Ezemma O, Kelley KJ, et al. Androgenetic Alopecia: Therapy Update. Drugs. 2023;83(8):701–715. https://link.springer.com/article/10.1007/s40265-023-01880-x

We find this article especially relevant, given the widespread prevalence of androgenetic alopecia (AGA) — a common hair disorder affecting up to 50% of men and women. Botulinum toxin (BT) is an emerging therapy for AGA, given its ability to increase blood supply, reduce dihydrotestosterone levels, and modulate fibroblast activity. However, evidence supporting BT use derives from limited prospective studies and one randomized trial lacking a control group.

This study by Melo et al represents the first triple-blind placebo-controlled trial investigating the outcomes of BT treatment in patients with AGA. The study included 13 men with AGA who were treatment-free for at least 6 months. Overall, eight points were tattooed on the scalp to standardize follow-up hair counts. At weeks 0 and 12, the patients received 25 IU of BT, injected into a 1-cm² area around the tattooed points on one half of the scalp. Saline was injected on the other side of the scalp, allowing the participants to serve as their own control. Analysis with clinical photographs and TrichoLAB technology provided an objective measure of treatment efficacy.

The results of this trial did not show improvement in terminal hair density, absolute change in total hair density, or alterations in the vellus/terminal hair ratio after 12 to 24 weeks of BT therapy. Although no benefit of BT therapy for male AGA was demonstrated, it is valuable to obtain negative results for purposes of patient counseling and future investigation. Furthermore, it is possible that BT diffused to the placebo side or affected adjacent areas, potentially influencing subsequent hair counts.

In summary, this trial did not support the use of BT for the treatment of patients with AGA. The study design likely reduced confounding by using patients as their own control. Additionally, Melo et al assessed the treatment efficacy precisely and objectively through hair analysis technology. However, the single-center format, small sample size, and unvalidated technology may have limited the researchers' ability to illustrate a meaningful benefit of BT therapy. In the future, larger multicenter studies are needed to further assess the utility of BT and other novel therapeutics in AGA management.