Drug Reaction With Eosinophilia and Systemic Symptoms (DRESS) Due to Trimethoprim: A Case Report.

Drug reaction with eosinophilia and systemic symptoms (DRESS) is a rare, severe, and potentially life-threatening drug hypersensitivity reaction characterized by cutaneous eruption, hematologic abnormalities, and internal organ involvement. Early recognition and prompt withdrawal of the culprit drug are crucial to reduce morbidity and mortality. We report a case of a 17-year-old woman with a psychiatric history who presented with a progressive maculopapular rash, fever, cough, and lethargy after initiation of trimethoprim for acne. Examination revealed a diffuse rash and bilateral chest crepitations. Laboratory studies showed elevated inflammatory markers, eosinophilia, and deranged liver function tests. Imaging demonstrated bilateral pulmonary infiltrates. Initial improvement was noticed with oral steroids, but her symptoms recurred on withdrawal. After which, corticosteroids were introduced, but despite this, her respiratory function deteriorated, necessitating intensive care admission. Microbiological investigations were negative for infection. Based on clinical features and drug association, along with European Registry of Severe Cutaneous Adverse Reaction Criteria (RegiSCAR) scoring, a diagnosis of DRESS syndrome secondary to trimethoprim, further complicated by pneumonitis, was made. The patient was treated with systemic corticosteroids with gradual clinical and biochemical improvement over six weeks. This case highlights trimethoprim as a potential but under-recognized trigger for DRESS syndrome. Early identification, discontinuation of the offending drug, and careful use of corticosteroids are essential to prevent severe complications. Clinicians should maintain a high index of suspicion for DRESS in patients presenting with rash, fever, eosinophilia, and multiorgan involvement following recent drug exposure.