Raw seafood can cause many different illnesses.

Side Effects of Eating Raw Seafood

by Sara Ipatenco

Certain types of raw seafood are culinary delicacies and include sushi, oysters and tuna tartare. While eating raw seafood that's been correctly prepared isn't likely to make you sick, eating undercooked or improperly cooked seafood can. Some types of raw seafood can even contain marine toxins that can be life-threatening. Arm yourself with all the raw seafood facts so you know what to eat and what to stay away from.

Food Poisoning

Food poisoning is always possible when you eat raw or undercooked seafood. Seafood can become contaminated with bacteria or viruses that can make you ill if you eat the food before it's fully cooked. Food poisoning can also occur if you eat a poisonous animal, such as a pufferfish, according to the University of Maryland Medical Center. Symptoms of food poisoning occur within a day or so after eating contaminated food, and usually include nausea, vomiting, abdominal pain and diarrhea. More serious food poisoning, such as botulism, can become life-threatening if it's not treated right away.

Fish and Shellfish Poisoning

Raw or undercooked shellfish can cause specific types of poisoning. Ciguatera poisoning is caused by eating contaminated tropical reef fish, such as barracuda, grouper, sea bass and snapper, and causes nausea, vomiting, diarrhea, excessive sweating, headache, muscle aches, weakness and dizziness. Scombrotoxic fish poisoning can occur by eating contaminated tuna, which is a common sushi ingredient, and mackerel. The bacteria causes rash, diarrhea, sweating, headache and vomiting. Paralytic shellfish poisoning causes numbness, tingling and temporary paralysis, and amnestic shellfish poisoning can cause diarrhea, nausea and short-term memory loss, according to the MedlinePlus website.

Mollusk Poisonings

Vibrio vulnificus is a poisoning that can occur by eating raw oysters. Most people can eat raw oysters without problems, but Vibrio vulnificus can also cause serious symptoms including chills, fever, nausea and blood poisoning. The bacteria is fatal in 40 percent of cases, notes the Clemson Cooperative Extension. The Norwalk virus is caused by improperly steamed clams or oysters. The virus causes nausea, vomiting, diarrhea and stomach cramps, but isn't fatal. Neurotoxic shellfish poisoning affects clams and mussels and leads to nausea, vomiting, diarrhea, mouth numbness, headache and dizziness.

Staying Safe

Cooking fish and seafood properly and thoroughly is the most effective way to reduce your risk of food poisoning. If you do eat raw seafood, order it from reputable restaurants. When you make your own raw fish, including sushi, at home, use commercially frozen fish, the Clemson Cooperative Extension recommends. These varieties are usually frozen at cold enough temperatures to kill bacteria. Keep seafood refrigerated until you're ready to eat it, as well, the CDC cautions. If you have a weakened immune system or liver problems, you shouldn't eat raw seafood. If you suspect that you've ingested contaminated raw seafood, seek medical attention or call a poison control center immediately.

About the Author

Sara Ipatenco has taught writing, health and nutrition. She started writing in 2007 and has been published in Teaching Tolerance magazine. Ipatenco holds a bachelor's degree and a master's degree in education, both from the University of Denver.

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