Botox for AGA: Yes, no... or Maybe?

Botox for AGA?

Botox injections have been suggested to be an option for androgenetic alopecia. English and Ruiz recently summarized data on the efficacy and safety of intradermal and intramuscular botulinum toxin injections for androgenic alopecia (AGA).

They conducted a literature search up to February 2021 and included five clinical studies in their evaluation. These included 4 prospective cohorts and 1 randomized clinical trial (RCT). Study length ranged from 24 to 60 weeks. No studies included control groups or compared botulinum toxin injections against approved treatments.

In total, there were 165 participants who were evaluated. Ages were between 19 and 57. All had androgenetic alopecia. Study durations ranged from 24 to 60 weeks. The number of botulinum toxin injection sessions ranged from 1 to 5 and included 30–150 units per session. The frequency of injection sessions spanned 3 weeks to 5 months. One study investigated intradermal injections directly into balding regions, whereas 4 studies investigated intramuscular injections into the frontalis, temporalis, periauricular, and occipitalis Response rates ranged from 75 to 79.1%. Hair count changes ranged from 18 to 20.9%. No serious adverse events were reported.

All in all, these data look encouraging but there are no control groups in these studies and participant numbers overall over low.   

The exact reasons why botox could help AGA is not clear. Shon found that botulinum toxin type A downregulated TGF-β1 expression in cultured human dermal papilla cells.  Research implicates the secretion of androgen-induced TGF-β1 in the progression of AGA – particularly in regard to DPC-related hair growth inhibition, anagen phase shortening, and hair follicle miniaturization.

Some proposed that muscular contractions of the frontalis, occipitalis, and temporalis might reduce blood supply by pinching vascular networks stemming from the supraorbital, supratrochlear, and carotid arterial branches. This could theoretically lead to a hypoxic state.

It could be that intramuscular injections may reduce the pressure that tissues are under. It could be that improve AGA by reducing tension across the galea aponeurotica. It has been shown that tissues under strain have increased intracellular oxidation and increased DHT and TGF-B1 activity

MAIN STUDY

English RS and Ruiz S et al. Use of Botulinum Toxin for Androgenic Alopecia: A Systematic Review Skin Appendage Disord 2022;8:93–100

STUDIES INCLUDED IN THE REVIEW

Freund BJ, Schwartz M. Treatment of male pattern baldness with botulinum toxin: a pilot study. Plast Reconstr Surg. 2010 Nov;126(5):246e–8e.

Singh S, Neema S, Vasudevan B. A pilot study to evaluate effectiveness of botulinum toxin in treatment of androgenetic alopecia in males. J Cutan Aesthet Surg. 2017 Jul‒Sep;10(3):163–7.

Zhang L, Yu Q, Wang Y, Ma Y, Shi Y, Li X. A small dose of botulinum toxin A is effective for treating androgenetic alopecia in Chinese patients. Dermatol Ther. 2019 Jul;32(4):e12785.

Shon U, Kim MH, Lee DY, Kim SH, Park BC. The effect of intradermal botulinum toxin on androgenetic alopecia and its possible mechanism. J Am Acad Dermatol. 2020 Dec;83(6):1838–9.

Zhou Y, Yu S, Zhao J, Feng X, Zhang M, Zhao Z. Effectiveness and safety of botulinum toxin type A in the treatment of androgenetic alopecia. Biomed Res Int. 2020;2020:1501893.