Scombroid Fish Poisoning: Histamine in Spoiled Fish


Scombroid fish poisoning is a food poisoning caused by histamine — the same chemical the body releases during an allergic reaction — that has built up in fish which was kept too warm after it was caught. The person who eats the fish is not allergic to it. The fish itself carries the dose. Within minutes to a couple of hours the face flushes, the head pounds, the heart races and a rash spreads, so the illness looks almost exactly like a fish allergy. Reviews describe it as the most common fish-related poisoning in the world, and also one of the most often misdiagnosed. This page explains how the histamine forms, which fish are involved, why cooking does not help, how doctors tell it apart from allergy, and what outbreak records and food-safety limits show.

For the chemistry of histamine itself — the enzyme that makes it from the amino acid histidine, its four receptors and the two enzymes that break it down — see Histidine, Histamine, and Allergy. For people who react to ordinary amounts of histamine in food, see the Low-Histamine Diet page.


Table of Contents

  1. Histamine Poisoning, Not an Allergy
  2. How Histamine Forms in Fish
  3. The Fish Most Often Involved
  4. Why Cooking, Canning and Freezing Do Not Remove It
  5. How the Fish Looks and Tastes
  6. Symptoms and Timing
  7. Severe Reactions and Heart Effects
  8. Medicines That Make It Worse
  9. How It Is Told Apart From Fish Allergy
  10. Treatment Reported in Studies
  11. How Often It Happens
  12. Outbreaks on Record
  13. Regulatory Histamine Limits
  14. What Is Not Known
  15. Key Research Papers
  16. Connections
  17. Featured Videos

Histamine Poisoning, Not an Allergy

The name comes from the Scombridae, the family of fish that includes tuna and mackerel, because these were the fish first linked to the illness. A 2016 review by Feng, Teuber and Gershwin traces the first description to Britain in 1799 and its return to the medical literature in the 1950s, when outbreaks were reported in Japan. The same illness is also called histamine fish poisoning or scombrotoxin fish poisoning. The US Food and Drug Administration (FDA) prefers “scombrotoxin poisoning”, partly because fish outside the tuna family are now known to cause it.

The key point is that it is a poisoning, not an immune reaction. In a true fish allergy, the immune system makes antibodies called immunoglobulin E (IgE) against fish proteins, and those antibodies make the person's own mast cells burst open and release histamine. In scombroid poisoning, the histamine is already in the fish. Anyone who eats enough of it can get sick, which is why whole tables of diners often fall ill together. A 2023 review by Zhernov and colleagues names the absence of an immunoglobulin E response as the single most important difference between the two conditions.

Hungerford, a scientist at the Food and Drug Administration's Pacific Northwest laboratory, points out in his 2010 review what makes this illness unusual among seafood toxins: it comes from mishandling of the fish after it is caught, not from a toxin the fish picked up from the food chain, as happens with ciguatera or shellfish poisoning.

How Histamine Forms in Fish

Three things have to come together.

  1. A fish rich in free histidine. Histidine is an amino acid. Some fish carry large amounts of it loose in their muscle, not locked into protein. Hungerford's 2021 review states that the high levels of free histidine needed for poisoning are found only in certain species of open-ocean (pelagic) fish.
  2. Bacteria that make the enzyme histidine decarboxylase. This enzyme removes one small piece from histidine and turns it into histamine in a single step. The Food and Drug Administration's hazards guidance explains that the bacteria responsible live naturally on the gills, skin and gut of live saltwater fish without harming them. When the fish dies, its defences stop and the bacteria start to grow into the muscle. A Japanese review of cases from 1998 to 2020 found that the bacteria isolated most often were Morganella morganii and Photobacterium damselae, with cold-tolerant species also found.
  3. Time at a warm temperature. The guidance describes histamine-forming bacteria as growing over a wide temperature range, faster at 70°F (21.1°C) or above than at 45°F (7.2°C), and particularly fast near 90°F (32.2°C). Some large fish such as tuna generate their own body heat, so the inside of the fish can stay warmer than the air around it after death.

The guidance adds several details that explain why the problem is hard to control:

The Centers for Disease Control and Prevention's outbreak reports state the same practical conclusion: the one effective means of prevention they describe is keeping the fish at or below 40°F (4.4°C) at all times from catch to consumption.

The Fish Most Often Involved

The sources read for this page name these fish:

The Food and Drug Administration guidance refers to a longer table of other species able to develop high histamine when kept warm; that table was not read for this page, so other species named in popular lists, such as herring and amberjack, are not covered here.

Not only fish. Taylor's 1986 review in Critical Reviews in Toxicology notes that cheese has been implicated in histamine poisoning on occasion, and a 2017 review by Schirone and colleagues adds that fermented foods in general can be involved in outbreaks and single cases.

A note on units. Histamine in food is given as parts per million (ppm), which is the same as milligrams per kilogram (mg/kg). Some papers use milligrams per 100 grams; 50 mg per 100 g equals 500 mg per kilogram.

Why Cooking, Canning and Freezing Do Not Remove It

This is the fact that surprises people most. Histamine is heat-stable. The Food and Drug Administration's guidance states that cooking can kill the bacteria and inactivate the enzyme, but once histamine has been produced, it cannot be eliminated by heat, including the high-pressure heating used for canning, or by freezing. Freezing may kill some of the bacteria, yet the enzyme survives freezing.

That is why canned, smoked, grilled and frozen fish all appear in the outbreak record. The Serbian outbreak came from canned sardines. In the 2017 French outbreak described below, histamine in the cooked tuna (3,720 mg per kilogram) was higher than in the leftover raw tuna (1,720 mg per kilogram). The Centers for Disease Control and Prevention's 2026 surveillance summary describes the marine toxins behind fish poisonings, scombroid toxin among them, as resistant to cooking or freezing.

How the Fish Looks and Tastes

Very often the fish seems perfectly fine. The Zhernov review describes the illness as following fish with “fine organoleptic characteristics” — that is, normal look, smell and taste. The Food and Drug Administration explains why: the rotten odours typical of slow, cold spoilage may be missing when fish has spoiled quickly at a high temperature, which is exactly when histamine builds up fastest. For this reason the guidance calls sensory checking on its own an ineffective control. The 2026 surveillance summary describes these marine toxins as tasteless and odourless.

Some people do notice something. The Centers for Disease Control and Prevention's 2007 outbreak report lists “a burning or peppery taste in the mouth” among the typical symptoms, and the Food and Drug Administration lists tingling or burning in or around the mouth or throat. These sensations come from the histamine acting on the mouth, often while the meal is still being eaten, rather than from any visible sign on the fish.

Symptoms and Timing

The Food and Drug Administration's guidance lists these symptoms:

The Centers for Disease Control and Prevention's 2007 report adds facial flushing, sweating and abdominal cramps, and a 1996 outbreak report from Taiwan describes blurred vision.

Timing. Onset is fast. The Food and Drug Administration gives a range of a few minutes to a few hours after eating. In a Japanese hospital outbreak, symptoms started between 20 minutes and two hours after the meal; a 2025 case report gives 30 minutes to two hours. Taylor's review describes the illness as having a short incubation period and a short duration.

How long it lasts. Sources differ. The Centers for Disease Control and Prevention's 2007 report states that symptoms usually resolve within several hours without medical treatment. The Food and Drug Administration's guidance gives a duration of 12 hours to a few days. In the 2003 California escolar outbreak, the median duration was 4 hours among those who took medicine and 1.5 hours among those who did not — a comparison that does not show medicine lengthened the illness, since people with worse symptoms are more likely to take medicine.

Severe Reactions and Heart Effects

Most cases are mild, but not all. The Centers for Disease Control and Prevention's 2007 report describes more severe symptoms — respiratory distress, swelling of the tongue and throat, and blurred vision — as needing medical treatment. Low blood pressure, breathing difficulty, throat or tongue swelling, and chest pain are signs hospitals treat as urgent; they are the same signs seen in anaphylaxis.

Heart effects have been reported:

Deaths are rare. A 2013 analysis by the Centers for Disease Control and Prevention estimated zero deaths a year from scombroid poisoning in the United States, against three for ciguatera; the 2011–2023 surveillance summary reported six hospitalizations among 597 scombroid illnesses.

Medicines That Make It Worse

The gut normally breaks down much of the histamine in food before it reaches the blood, using enzymes such as diamine oxidase and monoamine oxidase (explained on the histamine page). Anything that blocks these enzymes lets more histamine through.

Isoniazid, the tuberculosis medicine, is the best-documented example. Taylor's 1986 review lists isoniazid and aminoguanidine as drugs that strengthen histamine's effect by blocking the gut's histamine-breaking enzymes, so more unbroken histamine is absorbed. Two Japanese reports show what this looks like:

A 2020 review by Visciano and colleagues adds alcohol, enzyme deficiency and monoamine oxidase inhibitor antidepressants as conditions that can make dietary histamine dangerous. The picture is not settled, though: the 2018 systematic review of outbreak reports found no clear link between being ill and female sex, alcohol, prior medication, or eating histamine-releasing foods — noting that most reports lacked a full medical history. Decisions about medicines belong with a prescriber or pharmacist.

How It Is Told Apart From Fish Allergy

Several reviews state plainly that scombroid poisoning is often misdiagnosed as fish allergy, and the title of the 2016 Ridolo review sums it up: “it seems to be fish allergy but… it isn't.” Hungerford adds that doctors also have to separate it from reactions to Anisakis, a fish parasite whose proteins can trigger true allergy.

Why it matters. A person wrongly labelled as fish-allergic may be told to give up all fish for life, and may carry an emergency adrenaline injector they do not need. The Feng review notes that misdiagnosis as immunoglobulin E–mediated allergy keeps the disease under-recognised, and the 2022 Japanese review notes that people with histamine poisoning are taken to emergency wards with anaphylactic shock–like symptoms more often than is appreciated. In the 2025 Gingras case, a 30-year-old woman was diagnosed with anaphylaxis after eating salmon before the diagnosis was revised.

Clues that point to scombroid poisoning, drawn from the reviews:

A 2013 review by Banks and Gada describes scombroid poisoning as one of several “masqueraders” — with ciguatera, Anisakis and cross-reactions — that lead doctors to wrong conclusions about seafood allergy. More on true allergy is on the Food Allergy page.

Treatment Reported in Studies

Because histamine causes the symptoms, the treatment reported throughout the literature is antihistamines.

Mild cases often settle without treatment, as the Centers for Disease Control and Prevention's 2007 report describes. The 1999 report on two mass-casualty incidents found that recognising the cause early let paramedics treat many patients on the spot and release some from the scene.

How Often It Happens

Reported cases are a small fraction of real ones, because the illness is short, often mild, and often mistaken for allergy.

Outbreaks on Record

Across 103 incidents, the 2018 systematic review found an average histamine level in implicated foods of 1,107 mg per kilogram, but the range of plausible values ran from 24 to over 50,000, showing how widely the levels vary from one outbreak to another.

Regulatory Histamine Limits

Histamine is the one biogenic amine with legal limits in fish in the European Union, according to the Schirone review, because it can be fatal.

The Hungerford reviews describe how these limits are policed: by keeping a cold chain from boat to plate, by histamine testing with laboratory methods and newer rapid test kits, and, for canned tuna, by checking cooked loins for “honeycombing” — small holes in the flesh that the Food and Drug Administration describes as a sign of past temperature abuse.

What Is Not Known

Key Research Papers

  1. Feng C, Teuber S, Gershwin ME. Histamine (Scombroid) Fish Poisoning: a Comprehensive Review. Clinical Reviews in Allergy & Immunology. 2016;50(1):64-9. PubMed PMID: 25876709
  2. Hungerford JM. Scombroid poisoning: a review. Toxicon. 2010;56(2):231-43. PubMed PMID: 20152850
  3. Hungerford JM. Histamine and Scombrotoxins. Toxicon. 2021;201:115-126. PubMed PMID: 34419509
  4. Taylor SL. Histamine food poisoning: toxicology and clinical aspects. Critical Reviews in Toxicology. 1986;17(2):91-128. PubMed PMID: 3530640
  5. Colombo FM, Cattaneo P, Confalonieri E, Bernardi C. Histamine food poisonings: A systematic review and meta-analysis. Critical Reviews in Food Science and Nutrition. 2018;58(7):1131-1151. PubMed PMID: 27791395
  6. Ridolo E, Martignago I, Senna G, Ricci G. Scombroid syndrome: it seems to be fish allergy but... it isn't. Current Opinion in Allergy and Clinical Immunology. 2016;16(5):516-21. PubMed PMID: 27466827
  7. Zhernov YV, Simanduyev MY, Zaostrovtseva OK, Semeniako EE, Kolykhalova KI, Fadeeva IA, et al. Molecular Mechanisms of Scombroid Food Poisoning. International Journal of Molecular Sciences. 2023;24(1):809. PubMed PMID: 36614252
  8. Gingras V, Marois L. Case of scombroid syndrome mimicking an anaphylactic fish allergy. International Journal of Emergency Medicine. 2025;18(1):122. PubMed PMID: 40610892
  9. Ricci G, Zannoni M, Cigolini D, Caroselli C, Codogni R, Caruso B, et al. Tryptase serum level as a possible indicator of scombroid syndrome. Clinical Toxicology. 2010;48(3):203-6. PubMed PMID: 20230333
  10. Banks TA, Gada SM. Cross-reactivity and masqueraders in seafood reactions. Allergy and Asthma Proceedings. 2013;34(6):497-503. PubMed PMID: 24169056
  11. de Gregorio C, Ferrazzo G, Koniari I, Kounis NG. Acute coronary syndrome from scombroid poisoning: a narrative review of case reports. Clinical Toxicology. 2022;60(1):1-9. PubMed PMID: 34396875
  12. Eckstein M, Serna M, DelaCruz P, Mallon WK. Out-of-hospital and emergency department management of epidemic scombroid poisoning. Academic Emergency Medicine. 1999;6(9):916-20. PubMed PMID: 10490254
  13. Miki M, Ishikawa T, Okayama H. An outbreak of histamine poisoning after ingestion of the ground saury paste in eight patients taking isoniazid in tuberculous ward. Internal Medicine. 2005;44(11):1133-6. PubMed PMID: 16357449
  14. Morinaga S, Kawasaki A, Hirata H, Suzuki S, Mizushima Y. Histamine poisoning after ingestion of spoiled raw tuna in a patient taking isoniazid. Internal Medicine. 1997;36(3):198-200. PubMed PMID: 9144013
  15. Visciano P, Schirone M, Paparella A. An Overview of Histamine and Other Biogenic Amines in Fish and Fish Products. Foods. 2020;9(12):1795. PubMed PMID: 33287193
  16. Schirone M, Visciano P, Tofalo R, Suzzi G. Histamine Food Poisoning. Handbook of Experimental Pharmacology. 2017;241:217-235. PubMed PMID: 27752845
  17. Pennotti R, Scallan E, Backer L, Thomas J, Angulo FJ. Ciguatera and scombroid fish poisoning in the United States. Foodborne Pathogens and Disease. 2013;10(12):1059-66. PubMed PMID: 24093307
  18. Hartley CM, Hoang ST, Roberts VA, Chard AN. Foodborne Disease Outbreaks Associated with Marine Toxins - Foodborne Disease Outbreak Surveillance System, United States, 2011-2023. MMWR Surveillance Summaries. 2026;75(3):1-13. PubMed PMID: 42301912
  19. Centers for Disease Control and Prevention (CDC). Scombroid fish poisoning associated with tuna steaks--Louisiana and Tennessee, 2006. MMWR Morbidity and Mortality Weekly Report. 2007;56(32):817-9. PubMed PMID: 17703171
  20. Velut G, Delon F, Mérigaud JP, Tong C, Duflos G, Boissan F, et al. Histamine food poisoning: a sudden, large outbreak linked to fresh yellowfin tuna from Reunion Island, France, April 2017. Euro Surveillance. 2019;24(22):1800405. PubMed PMID: 31164189
  21. Pereira E, Elliot EL, Singleton LS, Otto M, Tesfai A, Doyle M, et al. An Outbreak Investigation of Scombrotoxin Fish Poisoning Illnesses in the United States Linked to Yellowfin Tuna Imported from Vietnam-2019. Journal of Food Protection. 2021;84(6):962-972. PubMed PMID: 33428741
  22. Petrovic J, Babić J, Jaksic S, Kartalovic B, Ljubojevic D, Cirkovic M. Fish Product-Borne Histamine Intoxication Outbreak and Survey of Imported Fish and Fish Products in Serbia. Journal of Food Protection. 2016;79(1):90-4. PubMed PMID: 26735034
  23. Peivasteh-Roudsari L, Rahmani A, Shariatifar N, Tajdar-Oranj B, Mazaheri M, Sadighara P, et al. Occurrence of Histamine in Canned Fish Samples (Tuna, Sardine, Kilka, and Mackerel) from Markets in Tehran. Journal of Food Protection. 2020;83(1):136-141. PubMed PMID: 31855616
  24. Amascual RH, Panganoron H, Gamba A, Irene E. Physicochemical and microbiological attributes of dried anchovies (Stolephorus commersonnii) in the formation of histamine along the supply chain. Italian Journal of Food Safety. 2023;12(3):11319. PubMed PMID: 37753205
  25. Feldman KA, Werner SB, Cronan S, Hernandez M, Horvath AR, Lea CS, et al. A large outbreak of scombroid fish poisoning associated with eating escolar fish (Lepidocybium flavobrunneum). Epidemiology and Infection. 2005;133(1):29-33. PubMed PMID: 15724707
  26. Wu ML, Yang CC, Yang GY, Ger J, Deng JF. Scombroid fish poisoning: an overlooked marine food poisoning. Veterinary and Human Toxicology. 1997;39(4):236-41. PubMed PMID: 9251176
  27. Tomaru A, Toda M, Hara-Kudo Y. [Literature Review on the Type of Fish and Histamine-producing Bacteria Associated with Histamine Poisonings in Japan]. Shokuhin Eiseigaku Zasshi. 2022;63(3):109-116. PubMed PMID: 35858795

PubMed Topic Searches

  1. PubMed: scombroid poisoning
  2. PubMed: histamine fish poisoning outbreaks
  3. PubMed: histamine poisoning and isoniazid
  4. PubMed: scombroid poisoning misdiagnosed as allergy

Other Sources

  1. US Food and Drug Administration. Fish and Fishery Products Hazards and Controls Guidance, Chapter 7: Scombrotoxin (Histamine) Formation. fda.gov/media/80248

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Connections

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