Toxic shellfish poisoning

The chemicals that cause toxic shellfish poisoning are produced by certain species of toxic algae, which are released into the shellfish when they eat the algae. There are 4 main kinds of poisoning. Find out about their causes and symptoms.

Types of shellfish poisoning

Bivalve shellfish (shellfish with two shells) like mussels or oysters can filter up to 10 to 12 litres of water an hour. That's more than 200 litres a day for each shellfish. Bivalves filter out phytoplankton (microscopic algae) and other particles as a food source. If these algae are toxic, then the toxins can accumulate in the shellfish, making them poisonous. These toxins can cause serious illness if the shellfish are eaten.

If you get sick after eating shellfish

If anyone becomes ill after eating shellfish:

  • phone Healthline for advice on 0800 61 11 16, or seek medical attention immediately
  • advise your nearest public health unit
  • keep any leftover shellfish in case it can be tested.
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