The Role of Minoxidil in Treatment of Alopecia Areata: A Systematic Review and Meta-Analysis

Abstract

Background/Objectives: Minoxidil, in addition to its vasodilatory effect, has also immunomodulatory properties that may be partially responsible for its efficacy in alopecia areata. The aim of the study was to evaluate the efficacy of monotherapy with topical or oral minoxidil in alopecia areata. Methods: A systematic review and meta-analysis of the efficacy of monotherapy with minoxidil in alopecia areata was conducted following the PRISMA guidelines. Efficacy of minoxidil in alopecia areata was evaluated separately for three groups of the patients: (1) treated with 5% topical minoxidil, (2) less than 5% topical minoxidil, and (3) oral minoxidil. Therapeutic response was defined as any regrowth of terminal hair. Results: Of 244 articles, 13 were considered eligible for the further analysis. The study included 372 patients with alopecia areata (338 using topical minoxidil and 34 taking oral minoxidil). The mean time of treatment ranged from 2 to 60 weeks (mean: 27 weeks). The response rate for 5% topical was 82% (95% CI 0.7-0.93) and 58% (95% Cl 0.5-0.67) for the less than 5% topical minoxidil group. For the group of patients treated orally, the response rate was 82%. Conclusions: Minoxidil, both topical and oral, may be beneficial in monotherapy in patients with alopecia areata. 5% topical minoxidil is characterized by significantly higher efficacy compared to minoxidil at a lower concentration. There are no sufficient data to recommend minoxidil as a first-line therapeutic option for alopecia areata.

Keywords: alopecia; alopecia areata; hair loss; meta-analysis; minoxidil; oral minoxidil; systematic review; topical minoxidil; treatment.

Figure 1

Flow chart diagram illustrating the database searches, number of publications identified, screened, and final full texts included in the systematic review.

Figure 2

Analysis of proportions for therapeutic response in patients treated with 5% topical minoxidil (p < 0.01). Cl—confidence interval.

Figure 3

Assessment of risk of bias for 5% topical minoxidil treatment (Egger test, Egger’s coefficient (b) = 5.18 and p = 0.001; the presence of publication bias). SE—standard error.

Figure 4

Analysis of proportions for therapeutic response in patients treated with less than 5% topical minoxidil (p = 0.28). Cl—confidence interval.

Figure 5

Assessment of risk of bias for less than 5% topical minoxidil treatment (Egger test, Egger’s coefficient (b) =1.21 and p = 0.66; no evidence of bias). SE—standard error.

Figure 6

The mechanism of action of minoxidil in alopecia areata treatment. ATP—adenosine triphosphate; Bcl-2—B-cell lymphoma 2; ERK—extracellular signal-regulated kinase; IL-1α—interleukin-1 alpha; PGE2—prostaglandin E2; VEGF—vascular endothelial growth factor.