The emerging applications of JAK inhibitors in dermatology - a systematic review.
BACKGROUND: Janus kinase (JAK) inhibitors are established treatments for selected dermatologic conditions, but their off-label use has expanded across refractory skin diseases. METHODS: We systematically searched MEDLINE, Embase, and Web of Science from inception to October 1, 2025, for studies reporting off-label JAK inhibitor use in dermatologic disorders beyond approved or late-phase trial indications. RESULTS: Of 9,182 records screened, 277 studies met the inclusion criteria, comprising 210 case reports, 55 case series, and 12 retrospective studies involving 764 patients. Owing to substantial clinical heterogeneity, findings were narratively synthesized using a structured disease-family framework. Off-label use most commonly involved lichenoid, neutrophilic, and granulomatous dermatoses. Overall, 725/764 (94.88%) patients experienced clinical benefit, including complete or near-complete response in 209/764 (27.35%) and significant or partial improvement in 516/764 (67.53%). Thirty-five patients (4.58%) showed no clinical change, and four (0.52%) experienced disease worsening. A total of 154 adverse events were reported, most commonly with tofacitinib; most were mild to moderate, although six were serious and 25 resulted in treatment discontinuation. CONCLUSION: JAK inhibitors demonstrate promising therapeutic potential across a broad spectrum of refractory dermatological diseases. The predominance of uncontrolled case-based evidence, heterogeneous dosing, and frequent combination therapy limits attribution of efficacy and safety to JAK inhibitor monotherapy. Prospective controlled studies are needed to better define their therapeutic role.