Paradoxical Rashes and JAK Inhibitor-Associated Acne in Hidradenitis and IBD Patients

Conclusions

• Paradoxical rashes are a biologic-associated phenomenon seen across multiple drug classes, not just TNF inhibitors.
• These rashes often have mixed and varied morphologies, including psoriasiform, eczematous, inverse, palmoplantar, impetiginized, and alopecia-like presentations.
• The underlying mechanism is thought to involve immune pathway shifts, especially interferon dysregulation, rather than classic psoriasis pathways alone.
• Paradoxical rashes can be dose-dependent and may be more common with higher-dose or higher-frequency biologic regimens.
• Switching from one TNF inhibitor to another often does not reliably resolve the rash, so these eruptions can be refractory.
• Management is often more successful when the rash itself is treated, including with agents that target the interferon pathway such as JAK inhibitors, methotrexate, apremilast, or light therapy.
• For some patients, continuing the needed biologic while adding rash-directed therapy can be effective.
• JAK inhibitor–associated acne is a recognized adverse effect, especially with JAK1-selective agents.
• When JAK-associated acne occurs, clinicians should consider demodex infestation as a frequent contributor and treat accordingly when present.
• Overall, the presentation concludes that recognizing the specific rash phenotype is essential for choosing whether to treat through, add adjunctive therapy, or change the underlying medication.