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

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. 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. Among 1,905 identified reports (baricitinib [n = 881], ritlecitinib [n = 515], tofacitinib [n = 489], ruxolitinib [n = 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. 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.