Case of scombroid syndrome mimicking an
anaphylactic fish allergy

Case of scombroid syndrome mimicking an
anaphylactic fish allergy

Scombroid syndrome, Fish allergy, Anaphylaxis, Food allergy

Abstract
Background Scombroid syndrome, a pseudo-allergic reaction caused by histamine-contaminated fish, is often
mistaken for type I hypersensitivity reactions due to overlapping clinical presentations. Unlike IgE-mediated
anaphylaxis, Scombroid syndrome results from histamine production by bacterial histidine decarboxylase in
improperly preserved fish. It accounts for 5% of U.S. food poisoning cases and manifests within 30 min to two hours
post-ingestion.
Case presentation Symptoms include rash, pruritus, vomiting, and tongue swelling, as exemplified by a case of a
30-year-old woman misdiagnosed with anaphylaxis after consuming salmon. However, typically mild and self-limiting,
severe cases may involve bronchospasm and arrhythmias. Diagnosis hinges on patient history, symptom onset, and
absence of food allergy markers, such as elevated tryptase. Management includes antihistamines and supportive care;
epinephrine and corticosteroids are reserved for severe reactions.
Conclusion Clinicians must distinguish Scombroid syndrome from anaphylaxis to ensure accurate treatment,
emphasizing proper fish preservation to prevent outbreaks.
Keywords Scombroid syndrome, Fish allergy, Anaphylaxis, Food allergy

Véronique Gingras1

and Louis Marois2,3,4*

2025

Peri Irawan

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