Sulfonamide-Induced DRESS Syndrome in a Patient With HIV Being Treated for Cerebral Toxoplasmosis

Background: Cerebral toxoplasmosis, a life-threatening opportunistic infection that can occur in patients with advanced human immunodeficiency virus (HIV) infection, is commonly treated with sulfonamide-based regimens such as trimethoprimsulfamethoxazole (TMP-SMX) or a combination regimen of pyrimethamine, sulfadiazine, and leucovorin (P-S-L).Drug reaction with eosinophilia and systemic symptoms (DRESS) syndrome is a rare but potentially fatal hypersensitivity reaction that complicates treatment, particularly among immunocompromised individuals.Case Report: A 41-year-old male with untreated HIV presented with right-sided weakness and visual disturbances.Neuroimaging and serology confirmed cerebral toxoplasmosis.The patient was initially treated with TMP-SMX but developed acute kidney injury, necessitating a change to P-S-L.Following an 8-day course of P-S-L, the patient developed fevers, a morbilliform rash, eosinophilia, transaminitis, and worsening renal function, and his RegiSCAR (Registry of Severe Cutaneous Adverse Reactions) score progressed from 2 to 4, indicating probable DRESS syndrome.The sulfadiazine component of P-S-L and the patient's earlier exposure to TMP-SMX were identified as potential triggers of DRESS syndrome resulting from sulfonamide cross-reactivity.Sulfadiazine was discontinued, and the patient's condition steadily improved after initiation of high dose systemic corticosteroids with a gradual taper.Conclusion: Diagnosing DRESS syndrome in immunocompromised patients is challenging because the symptoms overlap with infection and may evolve slowly.Cross-reactivity among sulfonamide antibiotics complicates therapy for opportunistic infections such as toxoplasmosis.This case highlights the importance of maintaining a high index of suspicion for DRESS syndrome in patients with HIV who are treated with sulfonamides.Early recognition, drug withdrawal, and corticosteroid therapy are essential to prevent severe outcomes.