BH21 Efficacy and safety of oral Janus kinase inhibitors in the treatment of alopecia areata: a systematic review and meta-analysis

Abstract

Alopecia areata (AA) is an autoimmune disorder characterized by T-cell-mediated damage to hair follicles. While systemic treatment options were historically limited, Janus kinase (JAK) inhibitors have emerged as a promising therapy. This systematic review and meta-analysis aimed to evaluate the efficacy and safety of oral JAK inhibitors compared with placebo in adults with moderate-­to-severe AA. A systematic search of databases was conducted from inception to 31 October 2025. We included randomized controlled trials evaluating oral JAK inhibitors in adults (≥ 18 years) with AA. Primary outcomes included the proportion of patients achieving Severity of Alopecia Tool (SALT) scores of ≤ 20 and ≤ 10, improvements in SALT by ≥ 50%, ≥ 75% and ≥ 90%, and treatment-related adverse events (AEs). Data were synthesized using random effects models to calculate odds ratios (ORs) and 95% confidence intervals (CIs). Twelve RCTs involving 4141 participants (mean baseline SALT score 86.0) met the inclusion criteria. Oral JAK inhibitors were significantly more effective than placebo across all primary efficacy endpoints. At week 24, the odds of achieving SALT ≤ 10 were 5.69 times higher for JAK inhibitors (95% CI 3.58–9.03), increasing to an OR of 9.40 by week 36 (95% CI 4.58–19.3). For SALT ≤ 20 at week 24, the OR was 7.99 (95% CI 5.13–12.4). Significant improvements were also noted for eyebrow and eyelash regrowth. Regarding safety, JAK inhibitors were associated with a higher risk of total AEs (OR 1.60, 95% CI 1.33–1.94), but no statistically significant difference was found for serious AEs (OR 1.04, 95% CI 0.69–1.57) or treatment discontinuation (OR 1.22, 95% CI 0.84–1.76). Oral JAK inhibitors are effective in promoting scalp, eyebrow and eyelash hair regrowth in patients with moderate-to-severe AA, with efficacy increasing progressively over time. The favourable safety profile of these agents is reassuring. Future research should prioritize head-to-head randomized controlled trials and long-term pharmacovigilance to explore comparative efficacy and safety.