Subcutaneous Versus Combined Subcutaneous and Intramuscular Botulinum Toxin for Androgenetic Alopecia: A Randomized Clinical Trial.

[BACKGROUND] Botulinum toxin A has emerged as an alternative treatment for patients who have contraindications to other therapies or as an adjuvant therapy in the treatment of androgenetic alopecia (AGA), although little is known about its safety and efficacy profile or the mechanism involved in this disease.

[OBJECTIVE] To evaluate the efficacy profile of botulinum toxin as monotherapy for AGA and compare subcutaneous vs subcutaneous and intramuscular application.

[METHODS] We conducted a 6-month, randomized, controlled trial to compare the efficacy of subcutaneous vs combined intramuscular and subcutaneous botulinum toxin application in men with AGA at a dermatology clinic in northeastern Mexico.

[RESULTS] A total of 15 men, aged 27-63 years, diagnosed with androgenetic alopecia (AGA) classified as stages III to V on the Hamilton-Norwood scale, and with no prior treatment for, at least, 6 months prior to being included in the study, were randomly allocated following a computer-generated sequence created prior to the start of the study. The sequence was blinded to both patients and investigators. Participants received a single session of botulinum toxin, administered either subcutaneously and intramuscularly (Group A) or subcutaneously as monotherapy (Group B). Each patient received 100 units of botulinum toxin. When comparing the initial and follow-up trichoscopic photographs of the frontal and vertex regions 6 months after botulinum toxin application using Fotofinder Trichoscale®, no significant changes were observed in hair density or the vellus/terminal hair ratio in either Group A or Group B (p>0.05), and a significant reduction in hair thickness was detected in the frontal region of both groups. Terminal hair count in the frontal region decreased significantly in Group A (p=0.035), whereas the reduction in Group B was not statistically significant. In the occipital region, none of the evaluated parameters showed significant changes (p>0.05). Additionally, no significant differences were seen between the 2 treatment modalities 6 months after application (p>0.05).

[CONCLUSION] Based on our study, we did not find any supportive results for the use of botulinum toxin in the treatment of AGA.