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Food Poisoning

What is food poisoning?

Food poisoning (foodborne illness) is caused by bacteria or viruses found in food.

Millions of Americans get food poisoning each year.

Food poisoning symptoms often look like stomach flu (gastroenteritis). Many people with a mild case think they have stomach flu or a virus.

What causes food poisoning?

Most food poisoning is caused by eating food that has certain types of bacteria or viruses. When you eat these foods, the bacteria keeps growing in your digestive tract. This causes an infection.

Foods can also make you ill if they have a toxin or poison made by bacteria growing in the food.

Several types of bacteria can cause food poisoning. Among the more common bacteria are:

Salmonella and Campylobacter

  • May be found in meat, poultry, and eggs that are raw or not cooked long enough (undercooked)
  • Can be found in dairy products that haven’t gone through a high-heat process to kill bacteria (are unpasteurized)
  • Can be found in raw fruits and vegetables

Clostridium perfringens

  • May be found in raw meat, poultry, eggs, or unpasteurized dairy foods
  • Can be found in vegetables and crops that have touched soil
  • Can cause food poisoning when soups, stew, and gravies made with meat, fish, or poultry are not refrigerated


  • May be found in unpasteurized milk and soft cheeses made with unpasteurized milk
  • May also be found in deli meats, hot dogs, and store-made deli salads

Staphylococcus aureus

  • Can spread to food when touched by someone with the bacteria
  • Can cause infection when foods such as meats and egg salad are not refrigerated

Escherichia coli (E. coli)

  • Can cause infection if you eat beef that is undercooked, mainly ground beef
  • Can be found in unpasteurized milk
  • Can be found in food or water that is contaminated

You can also get food poisoning from viral diseases such as Hepatitis A. These viral diseases:

  • Can pass from an infected person’s hands to the hands of food workers or into waste water (sewage)
  • Can spread when shellfish and other foods have touched unsafe, dirty water

Botulism is a rare but deadly form of food poisoning. It is caused by a bacteria (clostridium botulinum) that is found all over, even in soil and water. 

Botulism can happen when:

  • You eat low-acid foods that are not properly canned or preserved at home. These foods include meat, fish, poultry, or vegetables.
  • Infants eat raw honey or corn syrup. Babies under the age of 1 year old should never have honey or corn syrup.

Who is at risk for food poisoning?

Anyone can get food poisoning. But some people are more likely to get it than others. They are also at greater risk of getting very ill from it. This is because their body’s disease-fighting system (immune system) doesn’t work well.

People who are at greater risk include:

  • Young children. Their immune systems aren’t fully developed yet.
  • Older adults. Their immune systems do not work as well.
  • Pregnant women. A woman’s immune system changes during pregnancy. The unborn baby is also at risk.
  • People with long-term (chronic) disease. People with diseases such as diabetes or cancer have weaker immune systems.

What are the symptoms of food poisoning?

Food poisoning symptoms can look like the symptoms of stomach flu (gastroenteritis). Many people with mild cases of food poisoning think they have stomach flu.

Food poisoning symptoms can happen very fast. They may start a few hours after you eat the contaminated food.

Each person’s symptoms may vary. Symptoms may include:

  • Belly cramps
  • Watery or bloody diarrhea
  • Nausea and vomiting
  • Headache
  • Fever
  • Belly bloating and gas

Food poisoning symptoms may look like other health problems. Always see your health care provider to be sure.

How is food poisoning diagnosed?

Your health care provider will ask you when you became sick, what your symptoms are, and what foods you have eaten.

Your provider will also look at your past health. He or she will give you a physical exam.

You may have lab tests to find out what bacteria caused your illness. In some cases the cause can’t be found.

How is food poisoning treated?

Most mild cases of food poisoning are treated the same as stomach flu (gastroenteritis). If you have diarrhea or vomiting, you may lose a lot of fluids (get dehydrated). The goal is to replace your lost fluids and ease your symptoms.

For some types of bacterial food poisoning, your health care provider may give you a medicine that fights bacteria (an antibiotic). Antibiotics don’t work on infections caused by a virus.

In severe cases you may need to be hospitalized.

Call your health care provider if you can’t keep fluids down. Also call if your symptoms don’t go away.  

What can I do to prevent food poisoning?

To prevent food poisoning, wash your hands often. Also prepare and store food safely.

Always wash your hands after:

  • Using the toilet
  • Changing diapers
  • Smoking
  • Blowing your nose
  • Coughing or sneezing

When preparing food be sure to:

  • Wash your hands well before touching food
  • Wash your hands after touching raw meat, seafood, poultry, or eggs. Wash your hands  before touching any other foods.
  • Wash all fruits and vegetables well before eating
  • Use plastic cutting boards for cutting raw fish, poultry, or meat. They are easier to keep clean.
  • Clean any counter top or kitchen tool well after each use
  • Cook poultry, beef, and eggs for the right amount of time before eating

When choosing food to eat be sure to:

  • Not have any food made from unpasteurized milk
  • Not have any food made from raw or undercooked eggs, poultry and meat

When storing food be sure to:

  • Keep fruits and vegetables, cooked foods, and prepared foods away from raw meat and raw eggs
  • Refrigerate mayonnaise, salad dressings, and any foods that have them
  • Throw out food if you don’t know how long it’s been left out of the fridge
  • Throw out food if you’re not sure it is bad

Key points about food poisoning

  • Food poisoning is caused by bacteria and viruses found in food.
  • Symptoms may look like stomach flu (gastroenteritis).
  • Treatment focuses on replacing fluids and easing nausea and vomiting.
  • In severe cases you may need to be hospitalized.
  • To prevent food poisoning, wash your hands often. Also prepare and store food safely.

Next steps

Tips to help you get the most from a visit to your health care provider:
  • Before your visit, write down questions you want answered.
  • Bring someone with you to help you ask questions and remember what your provider tells you.
  • At the visit, write down the names of new medicines, treatments, or tests, and any new instructions your provider gives you.
  • If you have a follow-up appointment, write down the date, time, and purpose for that visit.
  • Know how you can contact your provider if you have questions.
Online Medical Reviewer: newMentor board-certified, academically affiliated clinician
Online Medical Reviewer: Piccolo, Amanda, RD
Date Last Reviewed: 4/29/2014
© 2000-2015 The StayWell Company, LLC. 780 Township Line Road, Yardley, PA 19067. All rights reserved. This information is not intended as a substitute for professional medical care. Always follow your healthcare professional's instructions.
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