Seafood Poisoning

Reviewed/Revised Dec 2023
VIEW PROFESSIONAL VERSION
Get the full details

What is seafood poisoning?

Certain seafood contains chemicals that are poisonous. Seafood poisoning is when you get sick from eating certain fish or shellfish that have toxins (poisons).

What are the symptoms of seafood poisoning?

Symptoms depend on the type of toxin in the fish.

Ciguatera poisoning

Ciguatera is a type of toxin that can build up in older fish. Cooking the fish doesn't get rid of the toxin.

About 2 to 8 hours after eating the fish, you feel:

  • Sick to your stomach

  • Belly cramps

  • Diarrhea (frequent, loose, watery poop)

Later, you feel:

  • Itchy

  • A pins-and-needles feeling

  • Headache

  • Muscle aches

  • Hot as cold, and cold as hot

  • Pain in your face

Symptoms can last for several months.

Puffer fish poisoning

Puffer fish (fugu) contains a dangerous toxin. Cooking or freezing the fish doesn't get rid of the toxin.

You feel:

  • Sick to your stomach

  • Belly cramps

  • Diarrhea (frequent, watery, or loose poop)

  • Paralyzed (unable to move your muscles)—this can cause you to stop breathing and die

If you think you or someone else may have puffer fish poisoning, call for emergency medical assistance (911 in most areas of the United States) or go to the hospital right away.

Scombroid poisoning

Scombroid is a toxin that grows in certain kinds of fish (mackerel, tuna, and bonito) if the fish isn't stored or refrigerated properly.

The fish may taste bitter or peppery.

Symptoms of scombroid poisoning:

  • Red, warm skin (flush)

  • Feeling sick to your stomach

  • Throwing up

  • Hives (pale red skin bumps that appear suddenly)

Shellfish poisoning

Shellfish poisoning comes from eating shellfish, such as mussels, clams, oysters and scallops, that contain a poison called saxitoxin.

Cooking shellfish doesn't prevent poisoning.

Symptoms of shellfish poisoning:

  • Pins-and-needles feeling around your mouth a few minutes after eating

  • Feeling sick to your stomach

  • Throwing up

  • Belly cramps

  • Muscle weakness

  • Not able to move arm and leg muscles

  • Trouble breathing

How do doctors treat seafood poisoning?

Specific treatments depend on the type of poison.

Doctors will:

  • Give you medicine (antihistamine)

  • Have you drink lots of fluids

  • Give you IV fluids (into your vein) if you can't drink

  • Give you medicine to help you stop throwing up, if needed

  • Do treatments to bring your body temperature, heart rate, and breathing back to normal

quizzes_lightbulb_red
Test your KnowledgeTake a Quiz!
Download the free Merck Manual App iOS ANDROID
Download the free Merck Manual App iOS ANDROID
Download the free Merck Manual App iOS ANDROID