Scombroid Fish Poisoning  

Scombroid is a type of foodborne illness that often occurs in fish such as tuna, mackerel, mahi mahi, anchovy, herring, bluefish, amberjack, and marlin. These fish contain naturally high levels of the chemical histidine. When these fish are not correctly refrigerated anywhere from the boat that caught them to the store that sold them, bacteria grow inside of them. The bacteria change the histidine into histamine. When you eat fish that contains a large amount of histamine, it causes an illness known as scombroid poisoning or histamine fish poisoning. Spoiled fish often looks, smells, and tastes normal. Sometimes it has a bitter or peppery taste. Correct cooking does not prevent this illness. This is because cooking does not affect the histamine.

Symptoms occur within 2 minutes to 2 hours after eating spoiled fish. Most people have mild symptoms that last only a few hours. In rare cases, symptoms may last several days. The most common symptoms include rash, diarrhea, flushing of the face and body, sweating, headache, nausea, and vomiting. You may also feel belly (abdominal) cramping, burning or swelling of the mouth, or a metallic or peppery taste. If you have asthma, you may have wheezing. How serious your symptoms are depends on how much fish you have eaten and how sensitive you are to histamine.

Symptoms usually go away in a few hours without any treatment. If symptoms continue, your doctor may tell you to take either an antihistamine or a medicine to prevent vomiting, or both. Scombroid poisoning does not mean that you have a seafood allergy, even though the symptoms are similar to those of an allergic reaction. Anyone who eats the spoiled fish could have a similar reaction. If this happened at a restaurant, it's important to let them know so that more customers are not served the fish.

Home care

  • Oral diphenhydramine is an antihistamine available over the counter at drugstores and grocery stores. You may take it to reduce itching if large areas of the skin are involved, unless your doctor has given you a prescription antihistamine.

  • Follow a light diet and rest as needed until you feel better.

Prevention

  • Refrigerate fish and seafood at less than 38°F (3.3°C) to prevent it from spoiling.

  • Don't eat fish that you think may be spoiled or poorly refrigerated.

  • Don't eat fish if it has an unusual peppery bitter taste.

Follow-up care

Follow up with your healthcare provider, or as advised.

Call 911

Call 911 if any of these occur:

  • Loss of vision

  • Shortness of breath, wheezing, or trouble breathing

  • Mouth, tongue, or throat swelling or trouble swallowing

  • Rapid heartbeat. This means more than 130 beats per minute.

  • Dizziness, weakness, or fainting

When to seek medical advice

Call your healthcare provider right away if any of these occur:

  • Your symptoms last for more than 24 hours or get worse

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