Fish poisoning symptoms, treatment and prevention
There are 4 common types of poisoning that can occur from eating fish:
- Scombroid fish poisoning
- Ciguatera fish poisoning
- Shellfish poisoning
- Rudderfish / Escolar diarrhoea
Scombroid fish poisoning
Fish poisoning has recently been brought to attention by the media, in particular, scombroid poisoning. It is still uncertain whether the case in question was caused by scombroid poisoning, none the less, it is good to raise awareness of the importance of food safety to avoid any serious consequences. This blog will focus on scombroid poisoning.
What is scombroid poisoning?
Poisoning can occur when certain species of fish are caught in warm water areas and are not chilled promptly/ consistently or at the correct temperature. These fish contain the chemical histadine and when incorrectly stored, bacteria within the fish breakdown the histadine into histamine. Histamine is known to cause the symptoms of food poisoning, within only a few hours [1,2].
It is important to note that cooking the fish thoroughly will not destroy the histamine toxin. A fish that is carrying histamine can often still appear, smell and taste normal. Some potential signs of contamination may be expressed as a bubbly, salty or sharp feel of the fish .
Fish that may produce the toxin
This type of fish poisoning derived its name from the Scombroidea fish family. Originally these fish were the only ones associated with scombroid poisoning. However, the Centers for Disease Control and Prevention (CDC) have largely associated poisoning with non-scombroid fish as well e.g. mahi mahi . Examples of the fish that can produce histamine are listed below.
- Butterfly kingfish
- Mahi mahi
Scombroid fish poisoning is often missed because it resembles an allergic reaction. The symptoms of poisoning can show within just minutes of eating the spoiled fish. Physical signs may include a diffuse blanching erythema, tachycardia, wheezing and hypotension or hypertension. People with asthma are more vulnerable to respiratory problems such as wheezing or bronchospasm.
The symptoms can be progressive and include:
The first signs of poisoning suggest an allergic reaction with the following symptoms:
- facial flushing/sweating
- burning-peppery taste sensations in the mouth and throat
- cold-like symptoms
The above symptoms can advance to:
- facial rash
- torso or body rash: The rash associated with scombroid poisoning is a form of urticaria, but most commonly does not include wheals that may be seen in true allergies.
- generalised oedema
- short-term diarrhoea
- abdominal cramps
In the worst cases, the poisoning may cause:
- blurred vision
- respiratory stress
- swelling of the tongue
- Treatment is in the form of supportive care such as fluids and oxygen.
- H1 and H2 receptor (histamine receptors) blocking medications can also be given with some success.
- Oral antihistamines are very effective, showing improvement within 10–15 minutes.
The symptoms can be extremely uncomfortable but generally are not fatal and resolve within 12 hours .
To prevent contamination, fish must be adequately chilled, immediately after catching – this will inhibit the production of histamine. The fish should be promptly submerged in ice, refrigerated or frozen and kept below 5°C until cooked.
Image sourced from: Temperature danger zone – NSW Food Authority
- Fish Poisoning Johns Hopkins Medicine Health Library
- Consumer Fact Sheet Naturally occurring seafood toxins
- SA Health. Government of South Australia. Fish poisoning – symptoms, treatment and prevention. December 2013.
- Ansdell V. Food Poisoning from marine Toxins. Centers for Disease Control and Prevention. August 2013.
Contact us for results focused nutritional advice
This article was written by our dietitian Belinda Elwin who is a Dietitians Association of Australia member and Accredited Practising Dietitian and Nutritionist.
If you have questions about fish poisoning or any other nutrition related issues contact us today! We‘ll provide you with a straightforward, efficient and very effective treatment plan targeted to your concerns.