Symptoms and Signs of Shellfish Poisoning

Medical Author: John P. Cunha, DO, FACOEP
Medically Reviewed on 9/24/2021

Doctor's Notes on Shellfish Poisoning

Shellfish poisoning is toxic poisoning that occurs when shellfish (mainly oysters, clams, scallops or mussels) are eaten by humans. Most shellfish come from saltwater habitats, but some species inhabit freshwater, and both can cause shellfish poisoning. Shellfish poisonings are categorized into four groups based on the specific toxins or chemicals that poison humans: amnesic shellfish poisoning (ASP), diarrheal shellfish poisoning (DSP), neurotoxic shellfish poisoning (NSP), and paralytic shellfish poisoning (PSP).

Symptoms of amnesic shellfish poisoning include permanent short-term memory loss, brain damage, and death. Symptoms of diarrheal shellfish poisoning include

Symptoms of neurotoxic shellfish poisoning include

  • slurred speech,
  • nausea, and
  • vomiting.

Symptoms of paralytic shellfish poisoning include

  • numbness and tingling sensations,
  • coordination loss,
  • speech defects,
  • nausea,
  • vomiting, and
  • death.

What Is the Treatment for Shellfish Poisoning?

Shellfish poisoning can cause symptoms that range from mild to severe and even deadly. If you think you may have a type of shellfish poisoning seek medical care. If symptoms are mild, call your health care provider or go to an urgent care facility. If symptoms are severe, call 911 or have someone take you to the emergency room immediately.   

Treatment for mild to moderate cases of shellfish poisoning involves supportive care to treat the symptoms. Supportive care for mild to moderate shellfish poisoning may include:

  • Intravenous (IV) fluids
  • Anti-diarrheal medications
  • Electrolyte replacements either IV or by mouth
  • Antiemetics to stop vomiting and nausea
  • Antiseizure medications if necessary

In severe cases of shellfish poisoning, in addition to the supportive care listed above, the use of life support systems such as a mechanical ventilator and oxygen and close cardiac monitoring until the toxin passes from the victim's system may be necessary.

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Kasper, D.L., et al., eds. Harrison's Principles of Internal Medicine, 19th Ed. United States: McGraw-Hill Education, 2015.