Topic Overview

What are marine toxins?

Marine toxins are chemicals
and bacteria that can contaminate certain types of seafood. Eating the seafood
may result in
food poisoning. The seafood may look, smell, and taste
normal. There are five common types of marine toxins, and they all cause
different symptoms.

Food poisoning through marine toxins is rare.
Marine toxin
poisoning occurs most often in the summer.

How is marine toxin poisoning diagnosed and treated?

Your doctor will do a medical history and a physical exam
and ask you questions about your symptoms and any fish you have recently eaten.
Laboratory testing is typically not needed.

There are no specific
treatments for marine toxin poisoning. Treatment generally consists of managing
complications and being supportive until the illness passes.
Dehydration caused by diarrhea and vomiting is the
most common complication.

To prevent dehydration, take
frequent sips of a rehydration drink (such as Pedialyte). Try to drink a cup of water or rehydration drink for each large,
loose stool you have. Soda
and fruit juices have too much sugar and not enough of the important
electrolytes that are lost during diarrhea, and they
should not be used to rehydrate.

Try to stay with your normal diet
as much as possible. Eating your usual diet will help you to get enough
nutrition. Doctors believe that eating a normal diet will also help you feel
better faster. But try to avoid foods that are high in fat and sugar. Also
avoid spicy foods, alcohol, and coffee for 2 days after all symptoms have

How can I prevent marine toxin poisoning?

keep seafood refrigerated or on ice. If you have a
weak immune system, you should consider not eating raw

To help avoid marine toxins:

  • Do not eat barracuda, especially if it is from
    the Caribbean Sea.
  • Refrigerate fresh tuna, mackerel, grouper and mahimahi. Remember that cooking does not destroy the toxins in spoiled or toxic seafood.
  • Check with health officials about local
    advisories on algae blooms, dinoflagellate growth, or red tide.
  • Do
    not eat fish or shellfish sold as bait. These products do not have to meet the
    same standards as seafood for eating.

What are the types of marine toxin poisoning?

Scombrotoxic fish poisoning:

  • Is caused by bacteria. The bacteria may produce
    a chemical (histamine) that results in the food poisoning.
  • Is
    usually found in finfish such as tuna, mackerel, and bonito.
  • Causes
    symptoms within 2 minutes to 2 hours of eating the fish. The most common
    symptoms are rash, diarrhea, flushing, sweating, headache, and vomiting.
    Burning or swelling of the mouth, stomach pain, and a metallic taste may also
    occur. Most people have mild symptoms that are gone within a few hours. In
    severe cases,
    antihistamines or
    epinephrine may be needed.
  • Cooking does
    not destroy the chemical, so buy your fish from a good source.

Ciguatera poisoning:

  • Is caused by ciguatoxins, which are produced by
    tiny sea plants called dinoflagellates.
  • Is usually found in
    tropical reef fish (such as barracuda) that kill other fish. But it may be
    found in grouper, sea bass, snapper, mullet, and other fish living in tropical
    waters. Common locations for these fish are the reefs surrounding Hawaii, the
    Virgin Islands, Puerto Rico, and Guam and other South Pacific
  • Causes symptoms within a few minutes to 30 hours. Symptoms
    include nausea, vomiting, diarrhea, cramps, excessive sweating, headache, and
    muscle aches. A feeling of burning and “pins and needles” as well as weakness,
    itching, and dizziness can occur. You may also experience unusual taste
    sensations, nightmares, and hallucinations. Symptoms usually are over in 1 to 4
  • Cooking does not destroy the toxins, so buy your fish from a
    good source.

Paralytic shellfish

  • Is caused by a dinoflagellate, although not the
    same one that causes ciguatera poisoning. These dinoflagellates have a
    red-brown color and in large numbers can cause a red streak called “red tide”
    in the ocean.
  • Is usually found in shellfish in colder coastal
    waters, such as the Pacific Northwest and New England. Shellfish that have
    caused the condition include mussels, cockles, clams, scallops, oysters, crabs,
    and lobsters.
  • Usually causes symptoms within 2 hours of eating the
    shellfish, although symptoms may occur within 15 minutes or after as long as 10
    hours. Symptoms usually begin with numbness or tingling in the face, arms, and
    legs, followed by headache, dizziness, nausea, and loss of coordination.
    Symptoms are usually mild, although severe symptoms have occurred.
  • Cooking does not destroy the toxins, so buy your fish from a good

Neurotoxic shellfish

  • Is caused by a type of
  • Is usually found in oysters, clams, and mussels
    from the Gulf of Mexico and the Atlantic Coast of the southern United
  • Cause symptoms in 1 to 3 hours. They include numbness, loss
    of coordination, an upset stomach, and tingling in the mouth, arms, and legs.
    They usually last 2 to 3 days.
  • Cooking does not destroy the toxins, so buy your fish from a
    good source.

Amnesic shellfish poisoning:

  • Is caused by toxins produced by a salt-water
  • Is found in shellfish such as mussels.
  • Causes
    symptoms within 24 hours. Symptoms include an upset stomach, dizziness,
    headache, disorientation, and short-term memory loss.
    Seizures may occur in severe cases.
  • Cooking does not destroy the toxins, so buy your fish from a
    good source.


ByHealthwise Staff
Primary Medical Reviewer E. Gregory Thompson, MD – Internal Medicine
Specialist Medical Reviewer W. David Colby IV, MSc, MD, FRCPC – Infectious Disease

Current as ofMarch 3, 2017