When Treatment Backfires: A Case Report of Sulfasalazine-Induced Hypersensitivity Syndrome in a Moroccan Patient With Crohn's Disease and Literature Review.

Sulfasalazine-induced hypersensitivity syndrome (SIHS) is a drug-specific variant of the syndrome known as drug reaction with eosinophilia and systemic symptoms (DRESS). It is a severe and unpredictable hypersensitivity reaction that can present with a spectrum of symptoms, ranging from mild rashes and unexplained fever to life-threatening systemic organ involvement. This diversity of symptoms often results in a diagnostic delay and/or misdiagnosis. Despite the serious nature of SIHS and the increasing number of cases being reported in the last decade, there is still no consensus regarding its management, and current approaches are based on case reports. The rarity, the unpredictability, and the seriousness of this condition make it difficult for proper randomized trials to be conducted. In the lack of such studies, case reports like ours are essential to deepen our understanding of this complex reaction. Here, we report a case of an 18-year-old Moroccan patient who was recently started on sulfasalazine for a newly diagnosed Crohn's disease. Three weeks later, the patient presented with a diffuse urticarial rash with a pustular scalp eruption and a fever. His workup revealed hyperleukocytosis with neutrophilia, eosinophilia, and hepatitis along with electrolytic abnormalities and elevated C-reactive protein without a definitive source of infection. The patient also admitted the use of metronidazole and spiramycin for a dental abscess five days prior to his admission. Thus, the diagnosis of SIHS with an associated acute generalized exanthematous pustulosis secondary to metronidazole and spiramycin was then made, and the patient was administered intravenous corticosteroids and oral antihistamines followed by a weaning oral regimen starting at 50 mg of oral prednisolone. Supportive management included intravenous fluids with electrolytes, topical emollients, and topical corticosteroids. His symptoms and biological parameters improved, and he was discharged after three weeks. At the outpatient follow-up two weeks later, he was in full remission.