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Why Does Tuna Hurt My Stomach?

Ever had a bad reaction to tuna? It might be a type of mild food poisoning—learn all about it in this article.

If you feel sick after eating canned tuna, it could be due to scombroid poisoning.

Scombroid poisoning is a type of food poisoning that occurs when fish—whether fresh, canned, or smoked—contains high levels of histamine because it wasn’t refrigerated properly after being caught, cooked, or, in the case of canned fish, opened.

According to an advisory note on the website of the U.S. Food & Drug Administration, scombroid poisoning is caused by eating scombroid and scombroid-like fish that has started to spoil and has specific types of bacteria growing on it. (The list includes amberjack, bluefish, bonito, escolar, mackerel, mahi mahi, marlin, and tuna.)

The FDA adds that scombroid poisoning happens when high levels of histamine are produced through the bacterial breakdown of fish flesh. It also goes on to explain that this type of food poisoning is usually not severe or long-lasting.

Symptoms of Scombroid Poisoning

Scombroid fish poisoning has symptoms similar to an allergic reaction, the California Department of Public Health writes on its website, and typically occurs within minutes to hours after consuming contaminated fish.

The most commonly observed symptoms of scombroid fish poisoning include a rash, diarrhea, flushing or redness of the face, and occasionally, the neck, arms, and upper body. Other symptoms may include sweating, headache, and vomiting.

The Department notes that most people who experience scombroid poisoning have mild symptoms, which typically subside within a few hours. However, in severe cases, it suggests that antihistamines or epinephrine may be used for treatment.

If you think that you have scombroid poisoning, seek medical advice immediately and do not rely solely on information published on the internet. A physician will be able to provide you with a proper diagnosis and recommend appropriate treatment if necessary.

How to Prevent Scombroid Poisoning

Cooked tuna should be eaten or refrigerated shortly after it’s prepared, and should never be left out at room temperature for extended periods of time.

Canned tuna should be eaten immediately, or as soon as possible, after opening. Many reported cases of scombroid poisoning have been linked to the consumption of canned tuna that has been opened and then stored for too long.1Hariri, O. E., Bouchriti, N., & Bengueddour, R. (2018). Risk Assessment of Histamine in Chilled, Frozen, Canned and Semi-Preserved Fish in Morocco; Implementation of Risk Ranger and Recommendations to Risk Managers. Foods (Basel, Switzerland)7(10), 157. https://doi.org/10.3390/foods7100157

To minimize the risk of scombroid poisoning, eat tuna within 1 to 2 hours after cooking or opening it. Treat it like any other perishable food—refrigerate any leftovers promptly. Keep in mind that leftovers only keep for 3 to 4 days in the fridge, after which they should be discarded.2U.S. Department of Agriculture (2023, March 24). What is the “2 Hour Rule” with leaving food out? AskUSDA. Retrieved July 25, 2023, from https://ask.usda.gov/s/article/What-is-the-2-Hour-Rule-with-leaving-food-out3U.S. Department of Agriculture (2020, July 31). Leftovers and Food Safety. Food Safety and Inspection Service. Retrieved July 25, 2023, from https://www.fsis.usda.gov/food-safety/safe-food-handling-and-preparation/food-safety-basics/leftovers-and-food-safety4(2023, January 18). Are You Storing Food Safely? U.S. Food & Drug Administration. Retrieved July 25, 2023, from https://www.fda.gov/consumers/consumer-updates/are-you-storing-food-safely

Unfortunately, even if you handle fresh or canned tuna properly after purchasing it, you are still at risk of scombroid poisoning.

Histamine, which causes the illness, is not deactivated by freezing, cooking, or reheating.5Chung, B. Y., Park, S. Y., Byun, Y. S., Son, J. H., Choi, Y. W., Cho, Y. S., Kim, H. O., & Park, C. W. (2017). Effect of Different Cooking Methods on Histamine Levels in Selected Foods. Annals of dermatology29(6), 706–714. https://doi.org/10.5021/ad.2017.29.6.706 If the fish wasn’t handled properly before processing, it will have elevated levels of histamine that can make you sick, no matter what precautions you take.

So, buy your canned tuna from brands that you can trust. And when handling fresh tuna, make sure to follow proper storage techniques before cooking to minimize the risk of getting sick.

Tying It All Together

Scombroid poisoning is a real risk when eating canned or fresh tuna.

To avoid getting sick, eat the tuna quickly after it’s been opened or cooked and don’t leave leftovers sitting around—put them in the fridge right away.

Still, you could get sick if the tuna wasn’t handled right before it got to you. So, buy from brands you trust and handle your fresh tuna right.

Know your author

Written by

Dim is a food writer, cookbook author, and the editor of Home Cook World. His first book, Cooking Methods & Techniques, was published in 2022. He is a certified food handler with Level 1 and Level 2 Certificates in Food Hygiene and Safety for Catering, and a trained cook with a Level 3 Professional Chef Diploma.