Scombroid Poisoning

Usually, scombroid symptoms start about 30 minutes to an hour after eating the poisoned food.

Scombroid poisoning is a disease due to the ingestion of contaminated food (mainly fish). In scombroid poisoning, bacteria have grown during improper storage of the dark meat of the fish and the bacteria produce scombroid toxin. Scombroid toxin, or poison, is probably a combination of histamine and histamine-like chemicals. The toxin or poison does not affect everyone who ingests it.

No test is 100% reliable for assessing fish for this toxin or poison. Cooking kills the bacteria, but toxins remain in the tissues and can be absorbed after the food is ingested.

Susceptible fish that produce scombroid poison include albacore, amberjack, anchovy, Australian salmon, bluefish, bonito, kahawai, herring, mackerel, mahi-mahi, needlefish, saury, sardines, skipjack, wahoo, and yellowfin tuna.

Other fish and foods probably will be added to the list if testing systems for the poison improve. Affected fish may have a metallic or peppery taste.

Symptoms of scombroid poisoning generally begin quickly, about 30 minutes to 1 hour after ingestion of the poison and include

• nausea,
• vomiting,
• flushing,
• abdominal cramps,
• diarrhea, and
• headache.

Other symptoms may include

• itching,
• hives,
• a burning sensation in the mouth,
• fever, or
• an unusual heart-pounding sensation.

Severe reactions include dropping blood pressure, racing heart, and wheezing.

Symptoms usually last about three hours, but some people experience discomfort for a few days.

Presumptive diagnosis is usually made on clinical observation of the symptoms together with the history of eating food (usually fish) a short time before the symptoms occurred. Additional supportive evidence is indicated by the person's response to treatment. Definitive diagnosis is performed infrequently with a test that detects abnormally high histamine levels in samples of fish that the person ingested.

Many doctors suggest that induced vomiting may help remove the poison if the poisoned person is awake and alert and has recently eaten the fish (or other food) within the past 3 hours. Oral charcoal may be used in some patients that are seen early after ingestion of large amounts of food likely containing significant amounts of scombroid poison. Some doctors recommend that the stomach should be pumped to remove foods before charcoal is administered. Moreover, patients are often given IV fluids as they may become dehydrated from vomiting.

Scombroid poisoning can be treated with diphenhydramine (Benadryl) 25 to 50 mg given orally (or initially by IV) every 6 hours and one ranitidine (Zantac) tablet twice a day as needed to reduce or stop symptoms.

A severe or prolonged reaction (hypotension, shortness of breath, tongue or throat swelling) requires medical treatment as soon as possible; this could be a medical emergency.

In people with mild symptoms, people can consult a doctor about treatment with available over-the-counter medications.

Scombroid poisons can reach levels that can cause symptoms in people (about 10 -100 mg of histamine per 100 grams of food [fish]) as early as six hours after the food has been unrefrigerated. It is recommended that food (mainly fresh caught fish) be immediately refrigerated and kept at 41 F (5 C) or below until it is cooked and eaten. Fish that are unrefrigerated, has a unusual or "bad" odor or has an odd appearance (honey-combed or dried out) should not be purchased for cooking or consumed.