Severe scombroid syndrome with biphasic evolution and suspected cardiac involvement in a young woman, a case report

Scombroid syndrome is a frequent cause of fish poisoning and typically presents with mild, self-limiting symptoms. Severe anaphylaxis-like reactions are uncommon, and a biphasic clinical course has not previously been reported. We describe the case of a 19-year-old woman who developed flushing, headache, generalized urticaria, facial edema, dyspnea, and hypotension approximately 30 minutes after ingesting raw amberjack tartare. Emergency treatment with adrenaline, antihistamines, corticosteroids, and intravenous fluids led to initial clinical improvement; however, three hours later, she experienced a recurrence of cutaneous, respiratory, and gastrointestinal symptoms, consistent with a biphasic reaction. The patient subsequently developed chest pain associated with transient electrocardiographic changes and mild troponin elevation, prompting further evaluation for suspected Kounis syndrome. Allergy assessment, including specific IgE testing and skin-prick testing with fresh fish, was negative, supporting a toxic rather than IgE-mediated mechanism. This case expands the clinical spectrum of scombroid syndrome by documenting a biphasic anaphylaxis-like presentation and underscores the importance of considering histamine fish poisoning in the differential diagnosis of severe food-related reactions. Careful evaluation is essential to prevent misdiagnosis and unnecessary long-term dietary restrictions.