Monday, October 21, 2013

Scombroid poisoning: watch out when eating fish

Chances are you didn't know this: consuming dark-fleshed oceanic fish that have been improperly processed or stored can lead to a peculiar type of food poisoning, so-called scombroid poisoning. Symptoms resemble a nasty allergic reaction; however, scombroid poisoning is not an allergy, although the mechanism is somewhat similar. The culprit is histamine, produced from the amino acid histidine when bacteria (usually Gram-negative species, e.g. Morganella morganii, Escherichia coli, Klebsiella sp. and Pseudomonas aeruginosa) present in the fish's skin and guts multiply and break down the fish's muscle tissue. Histamine is an organic nitrogen compound involved in the body's immune responses; specifically, it triggers the inflammatory response. During allergic reactions, histamine is released by immune system cells, whereas in scombroid poisoning, symptoms develop after the ingestion of histamine-containing fish.

Histamine. Image from: Wikipedia

The presence of histamine does not change the smell or appearance of the affected fish. Thus, a meal that tastes quite normal can still have unforeseen consequences. The symptoms of scombroid poisoning begin within 10 and 90 minutes after eating the spoiled fish and are highly unpleasant. They include flushed skin, a red rash (usually widespread), palpitations, headache, dizziness, sweating and a metallic or burning sensation in the mouth and throat. Gastrointestinal symptoms can include abdominal cramps, nausea, vomiting and diarrhea. Respiratory distress and vasodilatory shock have also been described. The rash lasts 2-5 hours and the other symptoms usually disappear within 3-36 hours.

Luckily, this type of food poisoning is rarely life-threatening. If the symptoms are severe enough to require medical attention, treatment involves antihistamines and supportive care.

Scombroid poisoning can occur after the ingestion of fresh, canned or smoked fish - usually tuna, mackerel, sardines or anchovies - which has been improperly refrigerated before processing or stored at room temperature after cooking. Histamine is heat-stable; once generated by bacterial growth, it remains present, you can cook the fish for as long as you like and it will still be there. When buying canned tuna or canned mackerel, just hope that the fish were processed quickly enough before canning - and, of course, make sure that you never eat fish from a can that has been opened several days earlier.

I won't let this discourage me from eating the occasional portion of tasty mackerel, though.

Source: Stratta P, Badino G (2012) Scombroid poisoning. CMAJ. 184(6): 674. doi: 10.1503/cmaj.111031


  1. Eating too much non veg is also not considered as a good sign for a healthy human. Sooner or later, you'll get into trouble if you eat junk food and meat of any animal.

    Arnold Brame

  2. It's a alarming news for the fish lovers the contamination of the water bodies have affected the health of fishes and the next level in supply chain human.

    Charlie Electra

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    1. While water contamination is a serious problem in its own right, scombroid poisoning is caused by improperly processing and storing fish - bacterial decomposition of fish meat is the culprit, not chemicals.

      Thanks for commenting!