Scombroid (histamine) food poisoning
Scombroid or histamine food poisoning is caused by eating certain types of fish that contain high levels of histamine due to bacterial enzyme activity in dead fish.
The histamine is not destroyed by cooking, smoking, freezing or canning. Prevention relies on the fish being chilled, or frozen soon after being caught and then being kept refrigerated or frozen until it is cooked, preserved or consumed.
Scombroid (histamine) fish poisoning
Scombroid (histamine) food poisoning is caused by eating finfish that carry scombrotoxin (histamine) and has been the cause of food poisoning outbreaks.
This toxin is produced by naturally occurring bacteria which convert the naturally occurring amino acid histidine in fish proteins to histamine. Upon death of a fish, histamine-forming bacteria may start to grow in muscle tissue, producing histamine. This is particularly the case if fish are caught in warm ocean waters, there is a substantial delay between fish death and chilling (e.g. longlining and gillnetting, where death may occur many hours before the fish is removed from the water), and/or fish are not stored under refrigeration.
Histamine does not affect the appearance, odour or taste of fish, and once formed is stable to both heating and freezing. Histamine production is more likely in raw, unfrozen fish but should not be discounted in other product forms such as frozen, dried, or canned fish, or fish products such as fish sauce (generally products containing > 30% fish). A threshold dose is considered 90 mg/100 g, with as low as 5-20 mg/ 100 g possibly harmful in susceptible individuals.
What types of finfish cause scombroid poisoning?
Scombroid food poisoning is primarily associated with consumption of fish flesh containing higher levels of histidine. This includes fish from:
- the family Scombridae:
- butterfly kingfish
- and non-scombroid fish:
- western Australian salmon and sockeye salmon
- cape yellowtail
- king gars
Who is affected?
Anyone can be affected by scombroid food poisoning. An individual’s sensitivity to histamine varies and is usually dependent on additional factors including susceptibility to asthma, metabolic differences, and drug therapies.
What are the symptoms?
Scombroid food poisoning symptoms are initially similar to some allergic reactions. Onset of symptoms varies from minutes to hours after consumption of fish with high levels of histamine. The time before onset of illness and the range of symptoms depends on how much fish is eaten, histamine level in the fish, and the individual histamine tolerance of the consumer. Symptoms generally persist for 8-12 hours and resolve with no or limited medication (e.g. anti-histamines) within 24 hours of consumption.
Symptoms may include:
- tingling, burning or peppery taste in the mouth and throat
- facial flushing, rash (hives) and/or localised skin inflammation
- nausea, vomiting, diarrhoea, abdominal cramps
Severe symptoms include:
- blurred vision
- respiratory distress
- swelling of the tongue.
Medical assistance should be sought if symptoms are severe, or call 13 HEALTH (13 43 25 84) for further advice.
Suspected food poisoning outbreaks should be reported to your local Queensland Health Public Health Unit.
Minimising the risk
In some cases, low levels of histamine may already be present in the fish when you receive it. To stop histamine increasing to levels of concern, always ensure the following:
- purchase from reputable suppliers who store fish on ice or under refrigeration
- keep fish cool while transporting it home
- keep fresh fish refrigerated for up to two days, or for longer periods store it in a freezer
- defrost frozen fish in the refrigerator, or cook from frozen or according to any package directions
- use packaged fish before its use-by or best-before dates.
Retailers, food service and caterers
- purchase from reputable suppliers, such as those that have a food safety program or quality assurance system
- only receive fresh fish at refrigerated temperatures (< 5°C)
- place the fish under refrigeration as soon as received and continue to store fish at refrigerated temperatures; if frozen, thaw under refrigeration
- when displaying fish for sale, always ensure there is enough ice on the product and refrigeration units are set to maintain product temperatures at less than 5°C
- fish should be processed or prepared quickly to ensure temperature control is maintained
- maintain stock rotation and sell product well in advance of its shelf life.
- ensure your business has systems in place to monitor the temperature of fish and dispose of stock that may have been unrefrigerated or outside temperature control.
- Hungerford JM. (2010) Scombroid poisoning: a review. Toxicon 56(2):231–243.
- SafeFish (2015) Scombroid fish poisoning: Essential knowledge for seafood businesses. https://www.safefish.com.au/reports/food-safety-fact-sheets/scombroid-fish-poisoning-faq-and-fact-sheet
- US FDA (2020) Scombrotoxin (histamine) formation. In: Fish and fishery products hazards and controls guidance 4th ed. Chapter 7. https://www.fda.gov/media/80248/download