Food Poisoning

Written by Marissa Selner and Winnie Yu | Published on July 18, 2012
Medically Reviewed by George Krucik, MD


Every year, millions of people eat food contaminated with bacteria, viruses, or parasites. The result can be food poisoning, an uncomfortable experience characterized by nausea, vomiting, and diarrhea. One in six Americans develops food poisoning each year.

The Types of Food Poisoning

Food poisoning can be caused by one of the following:


Norovirus is a contagious virus responsible for more than half of food poisoning cases. It is usually spread by unsanitary food preparation. Cooks or servers who do not wash their hands before touching food can spread the norovirus.


Botulism is a rare (but serious) illness caused by bacteria that grow in foods that have been improperly canned or preserved.

E. Coli

Escherichia Coli is a type of bacteria found in the intestines of all humans and animals. Certain strains can cause illness when ingested. The bacteria may contaminate meat during processing. It can also seep into foods that are not prepared safely.


Salmonella is a type of bacteria in the intestines of animals. It can live in animal products such as meat and eggs. If you cook your foods long enough or at high enough temperatures, it should kill all Salmonella present.

What Causes Food Poisoning?

Contamination most often occurs when foods or drinks come in contact with organisms in fecal matter. Foods eaten raw are common sources of illness because they do not go through the cooking process. Heat from cooking often kills pathogens on the food.

Due to the crowded conditions in many animal-processing facilities, meat, eggs, and dairy products are frequently contaminated. Many of the contaminants are killed when these products are cooked or pasteurized. However, in some cases, the bacteria or viruses are able to survive.

Water may also be contaminated with organisms that cause illness, especially in countries where water treatment is uncommon or not well managed.

Who Is at Risk for Food Poisoning?

Anyone can come down with food poisoning. Most people are infected at least once in their lives. Pregnant women, children, the elderly, and individuals with suppressed immune systems are at greater risk of complications.

What are the Symptoms of Food Poisoning?

Symptoms vary depending on the source of the infection. Common cases of food poisoning usually include the following symptoms:

  • abdominal pain
  • diarrhea
  • vomiting
  • mild fever
  • weakness
  • nausea
  • headaches

Symptoms of potentially life threatening food poisoning occur when:

  • you cannot keep fluids down
  • your diarrhea persists for more than three days
  • you have a fever higher than 101.5 degrees Fahrenheit
  • you are extremely thirsty and have a dry mouth
  • you pass little or no urine
  • you are unable to speak or see

If you experience any of these symptoms, you should contact your doctor or another health care professional as soon as possible.

How Is Food Poisoning Diagnosed and Treated?

Most cases of food poisoning resolve within several days. Food poisoning that causes severe symptoms may require medical treatment. Medical treatment may also be necessary when symptoms are prolonged.

Your doctor may be able to diagnose the type of food poisoning based on your symptoms. If your physician can’t reach a diagnosis, a stool sample can identify the cause of the poisoning.

Often, the treatment is designed to rehydrate you after you lose fluids from diarrhea and vomiting. This is usually done with intravenous (IV) fluids. Your doctor may prescribe antibiotics if your food poisoning is bacterial.

What Can I Expect in The Long Term?

Most victims of food poisoning recover at home within a few days. Although some otherwise healthy victims fall severely ill and die from complications, this is very rare. Patients who are elderly, very young, or who have other illnesses may be less able to cope with food poisoning. Their symptoms can be more severe. Pregnant women who contract certain forms of food poisoning may suffer miscarriages, stillbirths, or premature births.

How Can Food Poisoning Be Prevented?

The best way to prevent food poisoning is to handle your food safely and to avoid any food may be unsafe.

Some foods are more likely to cause of food poisoning because of the way they are produced and prepared. These include:

  • Meat, poultry, eggs, and shellfish. These foods may harbor infectious agents that are killed during cooking. If these foods are eaten raw, not properly cooked, or if hands and surfaces are not cleaned after contact, food poisoning can occur.
  • Sushi and other fish products that are served raw or undercooked.
  • Deli meats and hot dogs that are not heated or cooked.
  • Ground beef, which may contain meat from several animals that were handled by multiple people.
  • Unpasteurized milk, cheese, and juice.
  • Raw, unwashed fruits and vegetables.

Always wash your hands before cooking or eating food. Make sure that your food is properly sealed. Store refrigerated and frozen foods appropriately. Thoroughly cook meat and eggs. Anything that comes in contact with raw products should be sanitized before using it to prepare other foods. Make sure to ALWAYS wash fruits and vegetables before serving.

Stay informed about food recalls and widespread outbreaks of food-borne illness. Discard any foods you have already purchased that have been reported as contaminated.

Those who are at high risk of severe reaction to food poisoning—infants and young children, the elderly, people who have compromised immune systems, and pregnant women—should avoid eating high-risk foods such as sushi, deli meat, soft cheeses, and unpasteurized milk or juice.

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