Post-marketing safety signals of four JAK inhibitors for alopecia areata: an indication-restricted FAERS pharmacovigilance study.

[UNLABELLED] To characterize and compare the post-marketing safety profiles of Janus kinase (JAK) inhibitors used in alopecia areata (AA), including tofacitinib, baricitinib, ruxolitinib, and ritlecitinib.

[METHODS] Reports associated with JAK inhibitors in AA (2015-2025) were retrieved from the FDA Adverse Event Reporting System (FAERS). Disproportionality analyses utilized within-class and external non-JAK comparisons. Additionally, time-to-onset (TTO), serious adverse event (SAE) profiles, and sensitivity analyses were assessed.

[RESULTS] Among 1,905 identified reports (baricitinib [ = 881], ritlecitinib [ = 515], tofacitinib [ = 489], ruxolitinib [ = 20]), safety signals varied across agents. Tofacitinib showed signals involving neuropsychiatric and autoimmune events; baricitinib was associated with thrombocytosis, deep vein thrombosis, and breast cancer; ruxolitinib with pyrexia and elevated blood cholesterol; and ritlecitinib with gastrointestinal events and creatine phosphokinase elevation. TTO patterns were also heterogeneous, with earlier onset for tofacitinib and ruxolitinib, clustering within the first month for ritlecitinib, and a relatively delayed onset for baricitinib. Across the class, serious outcomes were most commonly related to infections, although the distribution of clinical outcomes differed by agent.

[CONCLUSIONS] JAK inhibitors used in AA demonstrated heterogeneous post-marketing safety patterns not fully captured by class-level warnings. These findings support agent-specific surveillance and individualized risk assessment in clinical practice.