Efficacy and Safety of Oral Janus Kinase Inhibitors in Adults and Adolescents with Alopecia Areata: A Systematic Review and Meta-Analysis of Randomised Controlled Trials.

backgroundAlopecia areata is an autoimmune disorder characterised by T-cell-mediated damage of hair follicles, resulting in non-scarring hair loss that can progress to complete scalp (alopecia totalis) or body hair loss (alopecia universalis). While long-term systemic options were historically limited, the emergence of Janus kinase (JAK) inhibitors has revolutionised the treatment of alopecia areata, even in patients with moderate-to-severe disease.

objectiveWe aimed to evaluate the efficacy and safety of oral JAK inhibitors compared with placebo in adults and adolescents with moderate-to-severe alopecia areata.

methodsMEDLINE, Embase and the Cochrane Central Register of Controlled Trials databases were searched from inception to 28 November, 2025. Randomised controlled trials evaluating oral JAK inhibitors in adolescents and adults (aged ≥12 years) with alopecia areata were included. Data extraction and risk of bias assessment were performed independently by multiple reviewers. Primary outcomes were the proportion of patients who achieved Severity of Alopecia Tool (SALT) scores of ≤10 and ≤20, and 50%, 75% and 90% reductions in SALT scores from baseline, as well as treatment-related adverse events (AEs). Data were synthesised using random-effects models to calculate odds ratios (ORs) and mean differences with 95% confidence intervals (CIs).

resultsTwelve randomised controlled trials involving 4141 participants (mean age 35.8 years, mean baseline SALT score 86.0) met the inclusion criteria. All trials enrolled adult participants, with the exception of one randomised controlled trial in which adolescents comprised 15% of the study population. Six trials were rated as having a low risk of bias, while six had "some concerns" primarily because of missing outcome data. 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 than placebo (95% CI 3.58-9.03); by week 36, this effect increased to an OR of 9.40 (95% CI 4.58-19.29). For SALT ≤20, the OR was 7.99 (95% CI 5.13-12.44) at week 24. Patients treated with oral JAK inhibitors were significantly more likely to achieve SALT50, SALT75 and SALT90 across all timepoints (weeks 12-36). 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 because of AEs (OR 1.22; 95% CI 0.84-1.76).

conclusionsOral JAK inhibitors are effective in promoting scalp, eyebrow and eyelash hair regrowth in adults and adolescents with moderate-to-severe alopecia areata, with a trend of higher response rates at later timepoints across studies. The favourable safety profile of these agents is reassuring. Future research should prioritise head-to-head randomised controlled trials and long-term pharmacovigilance to define comparative efficacy and safety.