Phototherapy for Atopic Dermatitis in the Era of Biologics and JAK Inhibitors: Mechanisms, Protocols, Evidence, and Positioning

Biologics and Janus kinase (JAK) inhibitors have transformed the treatment of atopic dermatitis (AD), but phototherapy remains accessible, relatively inexpensive and free of systemic drug interactions. This narrative review synthesises mechanistic data, clinical trials, real-world studies and emerging evidence on phototherapy alongside targeted systemic therapies. Narrowband ultraviolet B (NB-UVB) and UVA1 can improve pruritus and disease activity in selected patients, although the evidence base is heterogeneous and many trials predate contemporary outcome measures. Retrospective data suggest that patients with moderate, intermittent disease may be more likely to benefit than those with severe, continuously active AD. Small studies of short-cycle NB-UVB added to dupilumab suggest faster early improvement, without a clear adverse-event signal in the limited available datasets; however, durable benefit and the absence of additional toxicity have not been established. Evidence for combining phototherapy with oral JAK inhibitors is largely extrapolated from non-AD settings and remains speculative. Phototherapy therefore retains a role as a selected treatment or adjunct when systemic therapy is unsuitable, undesired or not readily accessible. Proposed stage-specific combination and flare-control strategies should be regarded as hypothesis-generating and require prospective validation before they can be considered standard practice.