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Understanding Food Poisoning -- the Basics

Medically Reviewed by Jabeen Begum on September 29, 2021

What Is Food Poisoning?

You can get food poisoning after eating food contaminated by viruses or bacteria.

Other types of food poisoning can be caused by parasites or exposures to toxins or chemical agents.

Food poisoning causes anything from mild to severe acute discomfort and may leave you temporarily dehydrated.

Mild cases may last only a few hours or days, but more serious types, such as botulism or certain forms of chemical or toxin poisoning, are severe and possibly life-threatening unless you get medical treatment.

What Causes Food Poisoning?

Many bacteria can cause food poisoning. People who are ill or infected can transmit staphylococcus bacteria to food they are preparing. People who eat or drink contaminated food or water can get travelers' diarrhea, usually caused by the bacterium E. coli. Salmonella poisoning can occur from eating contaminated poultry, eggs, and meat; though potentially fatal, most cases cause only mild symptoms. Harmful bacteria grow in cooked and raw meat and fish, dairy products, and prepared foods left at room temperature too long.

Canned goods, especially home-canned produce, can harbor a bacterium that needs no oxygen to multiply and is not destroyed by cooking. This bacterium causes botulism, a rare but potentially fatal food poisoning. Infants may develop botulism from eating honey because their immature digestive systems, unlike those of adults, cannot neutralize its naturally occurring bacteria.

Raw seafood, especially contaminated shellfish, may bring on food poisoning. Certain mushrooms, berries, and other plants are naturally poisonous to humans and should never be eaten; potato sprouts and eyes also contain natural toxins. Toxic mold can form on improperly stored fruit, vegetables, grains, and nuts. Deadly toxins are contained in certain types of mushrooms. Chemical food poisoning can be caused by pesticides or by keeping food in unsanitary containers.

How Can I Prevent Food Poisoning?

Here are some tips to stay healthy:

  • Always wash your hands before preparing any food. Wash utensils with hot soapy water after using them to prepare any meat or fish.
  • Don't thaw frozen meat at room temperature. Let meat thaw slowly in a refrigerator, or thaw it quickly in a microwave oven and cook right away.
  • Avoid uncooked marinated food and raw meat, fish, or eggs. Cook all such food thoroughly.
  • Check expiration dates on all foods.
  • In restaurants, send back any undercooked meat or egg products for further cooking. Ask for a new plate.
  • Don't eat any food that looks or smells spoiled or any food from bulging cans or cracked jars.
  • Set your refrigerator to 40 F or below. Never eat any prepared foods that have been out of a refrigerator more than 2 hours.
  • Keep juices or drippings from raw meat, poultry, shellfish, or eggs from contaminating other foods.
  • Carefully select and prepare fish and shellfish to ensure quality and freshness.
  • Keep separate cutting boards. Use one for raw meat, poultry, and fish and another for produce.
  • Avoid raw (unpasteurized) milk or foods made from raw milk.
  • Wash raw fruits and vegetables thoroughly before eating.
  • Drink only pasteurized juice or cider.
  • Be aware of proper home-canning procedures.
  • If you are ill with diarrhea or vomiting, do not prepare food for others.
  • Wash hands with soap after handling pets or cleaning up after animals.
  • Breast milk is the safest food for young infants. Breastfeeding prevents many food-borne illnesses and other health problems.
  • Do not feed honey to infants less than 1 year old.

Those at high risk, such as pregnant women and people with weakened immune systems, infants, and the elderly, should also:

  • Avoid soft cheeses.
  • Cook foods until they are steaming hot.
  • Take care with foods from deli counters.
WebMD Medical Reference

Sources

SOURCES:

Kliegman, R. Nelson Textbook of Pediatrics, 19th Edition. Saunders, 2011.

National Digestive Disease Information Clearinghouse: "Diarrhea."

Feldman, M. Sleisenger and Fordtran's Gastrointestinal and Liver Disease, 9th Edition, Saunders, 2010.

FamilyDoctor.org: "Fever in Infants and Children: Treatment."

USDA Food Safety and Inspection Service: "Safe Food Handling: Refrigeration and Food Safety," "Safe Food Handling: Cutting Boards and Food Safety."

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