Scombroid poisoning

This is the second most common type of fish food poisoning after ciguatera poisoning. It occurs as a result of eating fish which has decayed (or has ‘gone off’).

This can occur if fish is not properly refrigerated after it has been caught or poor hygiene on the part of the handler. What can happen is that the fish becomes warm after capture which causes it to release ‘histamine’ as part of a toxic reaction.

This histamine then causes a reaction within the person who has eaten the fish.

A major problem with this is that the symptoms of this food poisoning are very similar to those of an allergic reaction. This means that it can be missed or incorrectly diagnosed.

Causes of scombroid poisoning

Please see above: if fish which has been caught is not stored at the correct temperature within a refrigerator then it releases a toxin called ‘histidine’. Histidine naturally occurs in most species of fish and converts to histamine if the fish is exposed to a warm environment.

This is why it is so important to keep fish at cold temperatures.

If the fish is allowed to become too warm it then produces very high levels of histamine which is part of the decaying process. This process also produces other substances which form part of the toxic side effects.

Examples of fish which contain this toxin include tuna, mackerel, sardines and anchovies.

This type of food poisoning is not caused by a virus or bacteria.

Symptoms of scombroid poisoning

The symptoms of this particular type of food poisoning appear very quickly. In some cases, they occur within a few minutes of eating the infected fish.

They include:

• Nausea
• Dizziness
• Flushed face
• Sweating
• Burning taste in the mouth
• Headache
• Tachycardia (rapid heartbeat)
• Stomach pain

These symptoms can be mistaken for an allergic reaction so make sure that you mention that you have recently eaten fish.

These then develop into the following:

• Hives
• Oedema (swelling)
• Stomach cramps
• Diarrhoea

Any diarrhoea is likely to be short term only.

In severe cases you may experience a swollen tongue, blurred vision and difficulty in breathing.

These symptoms tend to last for 24 hours at most although they can return if you eat fish which has not been stored at the correct temperature, or on a bed of ice.

Treatment for scombroid poisoning

This usually involves fluids – to treat dehydration caused by vomiting or diarrhoea and oxygen – in cases of respiratory distress.

A type of medication called an antihistamine may also be given. This nullifies the affects of histamine.

In other words, it blocks the effect of histamine on the body.

Preventing scombroid poisoning

Be careful when eating canned fish such as sardines or tuna. Try to ensure that any fish you eat has been stored at the right temperature via a fridge or within ice.

If you have bought any fish which you think may have spoiled or ‘gone off’then do not eat this under any circumstances but throw it away instead.