Scombroid food poisoning

Scombroid food poisoning is a foodborne illness that typically results from eating spoiled fish.

Symptoms may include flushed skin, sweating, headache, itchiness, blurred vision, abdominal cramps, and diarrhea.

Onset of symptoms is typically 10 to 60 minutes after eating and can last for up to two days.

Rarely it is associated with breathing problems, difficulty swallowing, redness of the mouth, or an irregular heartbeat.

Scombroid occurs from eating fish high in histamine due to inappropriate storage or processing.

Fish commonly implicated include tuna, mackerel, mahi mahi, walu walu, sardine, anchovy, bonito, herring, bluefish, amberjack, and marlin.

These fish have high levels of histidine, which is converted to histamine when bacterial growth occurs during improper storage.

Cooking, smoking, or freezing does not eliminate the histamine.

Diagnosis is typically based on the symptoms.

The diagnosis is supported by a normal blood tryptase.

If a number of people who eat the same fish develop symptoms, the diagnosis is more secure.

Prevention: refrigeration or freezing fish right after it is caught.

Treatment: antihistamines such as diphenhydramine and ranitidine.

Epinephrine may be used for severe symptoms.

It is one of the most common type of seafood poisoning.

Symptoms typically occur within 10–30 minutes of ingesting the fish and generally are self-limited. 

People with asthma are more vulnerable to respiratory problems.

Symptoms may show over two hours after eating a spoiled dish. 

They usually last for about 10 to 14 hours, and rarely exceed one to two days.

Initial symptoms:

facial flushing/sweating

burning-peppery taste sensations in the mouth and throat





cold-like symptoms

Additional symptoms include: rash that most commonly does not include wheals.


short-term diarrhea

abdominal cramps

blurred vision

respiratory distress

swelling of the tongue

In rare cases, the poisoning may result in death.

Scombroid food poisoning is not brought about by ingestion of a pathogen.

Histidine is an amino acid that exists naturally in many types of food, including fish. 

When temperatures reach above 16 °C (60 °F), histidine is converted to the amine histamine via the enzyme histidine decarboxylase produced by symbiotic bacteria such as Morganella morganii.

This process is prevented by storing fish in a freezer.

Histamine is the main natural chemical responsible for true allergic reactions, so the symptoms produced are almost identical to a food allergy.

Rarely, cheese may be involved.

Differentiating scombroid from a fish allergy:  In scombroid, blood tryptase is generally normal, while in an allergic reaction, it is elevated.

Treatment is supportive care. 

Antihistamines such as diphenhydramine and ranitidine (H2 blockade) together with intravenous fluids may help with mild to moderate symptoms.

Epinephrine combined with a steroid may be used for severe symptoms.

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