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. Every year, about 30 cases are reported to health authorities. But because milder cases are often not reported, the incidence may be greater. 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 disappeared.

How can I prevent marine toxin poisoning?

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

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.