Management of Scombroid Poisoning
Treat scombroid poisoning primarily with H1-antihistamines and aggressive supportive care, recognizing this is a histamine toxicity syndrome—not an allergic reaction—that typically resolves within hours but can rarely cause life-threatening hypotension requiring vasopressor support. 1, 2
Immediate Recognition and Diagnosis
Suspect scombroid poisoning when patients develop symptoms within 20-30 minutes of eating fish (particularly tuna, mahi-mahi, or other dark-meat fish), presenting with facial flushing, rash, urticaria, peppery taste in mouth, headache, palpitations, and gastrointestinal symptoms 2, 3
The rapid onset (typically <30 minutes) and temporal relationship to fish consumption distinguishes this from IgE-mediated food allergy 2, 3
Recognize that this is histamine intoxication from bacterial decomposition of fish, not an allergic reaction—patients can safely eat the same fish species in the future if properly handled 3, 4
Initial Management and Supportive Care
Administer H1-antihistamines as first-line treatment (e.g., diphenhydramine or promethazine parenterally for moderate-to-severe cases) 2, 3
Provide aggressive fluid resuscitation with crystalloids for patients showing signs of distributive shock or hypotension, as severe cases can require large-volume resuscitation 5, 6
Add H2-antihistamines (ranitidine 150 mg or famotidine) as adjunctive therapy, though evidence specifically for scombroid is limited 1, 5, 6
Monitor vital signs closely, as approximately 25% of patients develop abnormal vital signs and rare cases progress to severe hypotension 2, 5
Management of Severe Cases
For refractory hypotension despite fluid resuscitation, initiate vasopressor support (phenylephrine or other vasopressors) as this represents severe histamine-mediated distributive shock 5, 6
Consider corticosteroids (methylprednisolone 1000 mg IV) for severe cases with cardiovascular instability, though this is based on case reports rather than controlled data 6
Do NOT use epinephrine routinely—scombroid is histamine toxicity, not anaphylaxis, and antihistamines are the appropriate treatment 1, 2
Admit patients with severe toxicity, cardiovascular instability, or those requiring repeated antihistamine doses for observation (typically resolving within 12-43 hours) 3, 5
Critical Pitfalls to Avoid
Do not misdiagnose as fish allergy—this is toxin-mediated poisoning, and patients do not need to avoid the fish species permanently 2, 3
Avoid telling patients they are "allergic to tuna" when they have scombroid poisoning, as this leads to unnecessary dietary restrictions 3
Do not treat routinely with epinephrine or corticosteroids as if this were anaphylaxis—antihistamines are the primary treatment 1, 2
Recognize that symptoms can be severe enough to mimic anaphylaxis (bronchospasm, hypotension, angioedema), but the underlying pathophysiology is direct histamine toxicity 1, 3, 5
Public Health Reporting
Notify local health authorities immediately to identify the fish source and prevent additional cases, as scombroid poisoning often occurs in outbreak clusters 2, 4
The toxin (histamine) is heat-stable and cannot be destroyed by cooking, so prevention requires proper refrigeration at ≤40°F (≤4.4°C) from catch to consumption 3, 4