Asian Journal of Case Reports in Medicine and Health

Background: Rituximab is used as first-line therapy for moderate-to-severe pemphigus vulgaris, but fever occurring around an infusion may be difficult to distinguish from infection or another drug-related event.

Case Presentation: A 59-year-old woman with relapsing pemphigus vulgaris was admitted with widespread flaccid bullae, oral involvement and positive Nikolsky and bulla-spread signs. She had been receiving prednisolone and dapsone. Before rituximab treatment, a urine culture grew Escherichia coli, and intravenous antibiotics were administered. During her first intravenous rituximab infusion of 1 g on 12 June 2026, she developed chills, a temperature of approximately 100°F and tachypnoea. The infusion was interrupted and restarted at 14:00, without further documented reaction. She remained afebrile for the rest of the observation period. Low-grade fever recurred between 15 and 18 June during antibiotic treatment. Blood cultures were advised but were not obtained because the family declined sampling. The fever resolved by 19 June. A second 1 g rituximab infusion was administered on 26 June with the same premedication and without a documented reaction. The initial event was reported to the Pharmacovigilance Programme of India, and a Naranjo score of 3 indicated a possible adverse drug reaction.

Conclusion: The timing and resolution of the first episode support a mild infusion-related reaction, whereas the later febrile episodes remain difficult to attribute because bacteriuria and concurrent antibiotic treatment offered alternative explanations. Careful documentation of the clinical chronology is essential for cautious causality assessment.