Scombroid Fish Poisoning
Flushed, itchy and pounding headache within an hour of eating tuna, mackerel or mahi-mahi? It may be scombroid: histamine from badly stored fish, not a fish allergy. It looks just like an allergic reaction, and antihistamines usually fix it.
It’s not a fish allergy, it’s badly stored fish. Blame the fridge, not your immune system.
Symptoms
- Start within minutes to an hour of eating
- Flushing of the face and neck, hives, itch and sweating
- A peppery, metallic or tingling taste in the mouth while eating
- Headache, palpitations, dizziness, nausea, cramps and diarrhoea
- Usually settles within a few hours, and almost always within a day
- A big clue: several people who ate the same fish get sick together
How it happens
- Fish such as tuna, mackerel, mahi-mahi, sardines, anchovies and bonito naturally contain lots of histidine.
- If the fish isn’t kept cold enough after it’s caught, bacteria turn histidine into histamine.
- The fish can look and smell normal. Cooking, canning or freezing doesn’t destroy histamine.
- The name comes from the Scombridae family (tuna and mackerel).
What helps
- Antihistamine tablets usually ease symptoms quickly.
- Severe cases with low blood pressure or wheeze need emergency care. Call 000.
- Report it to the restaurant and your state food authority so others aren’t affected.
- You don’t need to avoid fish afterwards: it isn’t an allergy, and it won’t make you allergic.
Weird but true
- Doctors often misdiagnose it as a seafood allergy, leading to years of avoiding fish unnecessarily.
- People taking isoniazid (a tuberculosis medicine) can react more strongly, because it slows histamine breakdown.
- Its cousin ciguatera, from reef fish, causes the strange sensation of cold feeling hot.
Common questions
Is scombroid an allergy?
No. It’s histamine poisoning from fish that wasn’t kept cold enough. Anyone who eats enough histamine can react, and it doesn’t mean you’re allergic to fish.
Which fish cause scombroid?
Mostly tuna, mackerel, mahi-mahi, sardines, anchovies and bonito, which are rich in histidine that bacteria turn into histamine.
Does cooking prevent scombroid?
No. Histamine isn’t destroyed by cooking, canning or freezing. Prevention depends on keeping fish cold from catch to plate.
Helpful resources
- NSW Food AuthorityReport suspected food poisoning in NSW.
Evidence and more information
maladywise.com/scombroid/