Histamine Poisoning (Scombroid Poisoning)
Histamine poisoning, also known as scombroid poisoning, is a foodborne illness caused by ingestion of fish or other foods containing abnormally high levels of histamine (typically >50 mg/100g), resulting in symptoms that clinically mimic IgE-mediated allergic reactions but occur without an immune response. 1, 2
Pathophysiology
- Histamine is produced when bacteria containing histidine decarboxylase enzymes convert the amino acid histidine to histamine in improperly stored fish. 2, 3
- The condition occurs most commonly with scombroid fish (tuna, mackerel, bonito) and scomberesocid fish, but also affects non-scombroid species including mahi-mahi, bluefish, and sardines. 2, 4
- Unlike true food allergy, this is a toxic reaction—there is no IgE antibody involvement, and anyone consuming the contaminated fish can develop symptoms. 1
- Other biogenic amines, cis-urocanic acid, and histamine liberators in spoiled fish may potentiate the toxic effects. 3
Clinical Presentation
Symptoms typically begin within minutes of ingestion and include: 2, 5
- Cutaneous manifestations: Facial flushing (often sunburn-like rather than urticarial), pruritus, rash, hives 1, 6
- Oral symptoms: Burning or peppery taste in the mouth 4, 2
- Gastrointestinal symptoms: Nausea, vomiting, diarrhea, abdominal cramps 4, 2
- Cardiovascular symptoms: Tachycardia, hypotension in severe cases 6, 5
- Severe manifestations (requiring medical treatment): Respiratory distress, tongue/throat swelling, blurred vision, bronchospasm, and potential asthma exacerbation in susceptible individuals 4, 5
Duration is typically self-limited, resolving within several hours to 24 hours. 2, 4
Key Diagnostic Features Distinguishing from Anaphylaxis
Critical differentiating factors include: 1
- Multiple individuals affected if they consumed the same fish (unlike true allergy which is individual-specific) 1
- Normal serum tryptase levels (tryptase peaks at 60-90 minutes in anaphylaxis and remains elevated up to 6 hours) 1, 7
- Cutaneous manifestation more commonly presents as flush rather than urticaria 1
- No prior sensitization required—first exposure can cause symptoms 2
- The fish may appear and smell normal despite dangerous histamine levels 2
Management
Treatment is primarily supportive with antihistamines: 4, 2
- H1 antihistamines are effective for symptom relief (unlike in true anaphylaxis where they are inadequate as monotherapy) 1, 4
- Epinephrine is NOT required for typical cases but may be needed for severe respiratory symptoms or cardiovascular collapse 1, 5
- Most cases resolve without medical intervention 4
Prevention
The only effective prevention is consistent temperature control of fish at ≤40°F (≤4.4°C) from catch to consumption. 4
- Fish with histamine concentrations exceeding 50 mg/100g are considered hazardous 2
- Proper refrigerated storage prevents bacterial histamine formation 2
- Visual inspection and smell cannot reliably detect contaminated fish 2
Additional Context
- Histamine poisoning can also rarely occur from certain cheeses, particularly Swiss cheese, when contaminated with histamine-producing bacteria. 2
- Monosodium glutamate can trigger endogenous histamine release and cause similar symptoms. 6
- Certain medications, particularly isoniazid, can cause monoamine (histamine/tyramine) poisoning after ingestion of high-monoamine foods, though this is rare. 1