Drug reaction with eosinophilia and systemic symptoms

Drug Reaction with Eosinophilia and Systemic Symptoms (DRESS), also known as Drug-Induced Hypersensitivity Syndrome (DIHS), is a severe, potentially life-threatening adverse drug reaction characterized by an extensive skin rash, fever, elevated blood eosinophil counts (eosinophilia), and internal organ involvement. The condition typically develops 2 to 8 weeks after initiation of the causative medication, which distinguishes it from many other drug reactions that occur more rapidly. Commonly implicated drugs include aromatic anticonvulsants (such as carbamazepine, phenytoin, and lamotrigine), allopurinol, sulfonamide antibiotics, dapsone, minocycline, and vancomycin. DRESS affects multiple body systems. The skin is almost always involved, presenting with a widespread maculopapular rash that may progress to erythroderma, facial edema, and occasionally blistering. Lymphadenopathy is common. Internal organ involvement most frequently affects the liver (hepatitis), but the kidneys (interstitial nephritis), lungs (pneumonitis), heart (myocarditis), and thyroid can also be affected. Hematologic abnormalities include eosinophilia, atypical lymphocytosis, and occasionally thrombocytopenia. Reactivation of human herpesvirus 6 (HHV-6) and other herpesviruses has been strongly associated with the syndrome and may contribute to its severity and prolonged course. Mortality rates are estimated at approximately 5–10%, primarily due to liver failure or multi-organ involvement. Treatment centers on immediate withdrawal of the offending drug, which is the most critical intervention. Systemic corticosteroids are the mainstay of pharmacologic treatment for moderate to severe cases, typically initiated at doses equivalent to 1–1.5 mg/kg/day of prednisone with a slow taper over several weeks to months to prevent relapse. In refractory or severe cases, intravenous immunoglobulin (IVIG), cyclosporine, or other immunosuppressive agents may be considered. Long-term follow-up is essential, as autoimmune sequelae—particularly autoimmune thyroiditis and type 1 diabetes mellitus—can develop months after the acute episode. Genetic susceptibility has been identified, with certain HLA alleles (such as HLA-B*58:01 for allopurinol-induced DRESS and HLA-A*31:01 for carbamazepine-induced DRESS) conferring increased risk, and pharmacogenomic testing is recommended in some populations before prescribing high-risk medications.

Data sourced from FDA regulatory filings and ClinicalTrials.gov. Updated periodically.

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