Everything You Need to Know About Food Poisoning

Medically Reviewed By Jerlyn Jones, MS MPA RDN LD CLT
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Food poisoning is an illness that results from eating contaminated food. Some toxins that result in food poisoning appear naturally in food, while others come from the environment. This article defines food poisoning and discusses the symptoms, causes, and treatments related to the illness. It also provides tips on how to prevent food poisoning.

What is food poisoning?

Young male child sleeping at a picnic
Manu Prats/Stocksy United

Food poisoning is an illness that results from eating contaminated food. Approximately 48 million people in the United States experience food poisoning each year. This is despite the American food supply being among the safest in the world.

Among these cases, approximately 128,000 require hospitalization, and 3,000 are fatal.

Food poisoning is the result of bacteria, viruses, and toxins in our food. Some of these occur naturally in our food, while others accumulate from the environment.

The most common causes of food poisoning are:

  • bacteria and viruses
  • parasites
  • molds, toxins, and contaminates
  • allergens

Most cases of food poisoning only last a few days before clearing.

What are the symptoms of food poisoning?

The most common symptoms of food poisoning include:

These symptoms may range from mild to severe, depending on the cause of your food poisoning. They typically begin within 1–2 days of eating contaminated food. However, you may see an onset of symptoms anywhere from a few hours to several weeks later. You may also experience a lack of energy, a loss of appetite, and dehydration.

Learn how green poop is a possible sign of food poisoning.

When to contact a doctor

You should contact your doctor and seek medical care if you experience any of the following:

  • blood in your diarrhea
  • high fever over 102ºF (38.8ºC)
  • persistent vomiting that makes it difficult to keep liquids down
  • diarrhea that lasts longer than 3 days
  • dehydration, which may cause:
    • an extremely dry mouth or throat
    • dizziness
    • little to no urination

What causes food poisoning?

The most common causes of food poisoning are bacteria, viruses, and toxins.

Cause of food poisoningWhere it is foundOnset of symptoms
Staphylococcus aureusin foods that are not typically cooked after you handle them, such as sliced meats, sandwiches, and pastries30 minutes to 8 hours
Vibrioin raw or undercooked shellfish, especially oysters2–48 hours
Clostridium perfringensin beef and poultry, gravies, and dried or precooked food6–24 hours
Salmonellain raw or undercooked chicken, turkey, and other meats, eggs, unpasteurized milk and juice, and raw fruits and vegetables6 hours to 6 days
norovirusin leafy greens, fresh fruits, shellfish, and unsafe water12–48 hours
Clostridium botulinumin improperly canned or fermented foods18–36 hours
Campylobacterin raw or undercooked poultry, unpasteurized milk, and contaminated water2–5 days
Escherichia coliin raw or undercooked ground beef, unpasteurized milk and juice, raw vegetables, raw sprouts, and unsafe water3–4 days
Cyclosporain raw fruits or vegetables and herbs1 week
Listeriain soft cheeses, raw sprouts, melons, hot dogs, pates, deli meats, smoked seafood, and unpasteurized milk1–4 weeks

What are the risk factors for food poisoning?

Anyone can develop food poisoning if they eat contaminated foods. However, there are certain groups of people who are at higher risk of developing food poisoning and who may have a more severe case if they do get it.

These groups include:

  • people who are pregnant
  • children under 5 years old
  • adults over the age of 65 years
  • people with a weakened immune system

How do doctors diagnose food poisoning?

Most cases of food poisoning are never officially diagnosed. This is because the majority of people with food poisoning recover on their own at home.

It is often difficult to tell whether or not you actually have food poisoning. It is sometimes easier to tell if more people who ate the same thing also fall ill. However, the symptoms typically clear on their own within a few days of onset.

If you have a severe case of food poisoning and require medical treatment, your doctor may run blood tests or stool tests to check for bacteria and toxins that may be the cause of your illness.

How do you treat food poisoning?

Most cases of food poisoning are treatable at home and do not require medical care. However, if you are in a high risk group or if your child develops food poisoning, you may want to check with a doctor.

Symptoms of food poisoning generally go away within a few days. During this time, there are some ways you can help yourself be more comfortable and prevent dehydration. For example:

  • Drink plenty of fluids, even if you can only sip them.
  • Rest as much as you can.
  • Avoid alcohol, fizzy drinks, caffeine, and spicy or fatty foods.
  • Eat when you feel you can, and stick to small, light, non-fatty meals to begin with.

If your symptoms last longer than a few days to a week, your doctor may recommend further treatment. These treatments may include antibiotics or medications to help you stop vomiting. In severe cases, you may require hospitalization to receive IV fluids and so that your doctor can monitor you.

Read about what to expect when you are recovering from food poisoning.

What are the potential complications of food poisoning?

The most common complication of food poisoning is dehydration. Some symptoms of dehydration include:

  • extreme thirst
  • a dry mouth
  • urinating less often than usual
  • lightheadedness, dizziness, or fainting
  • tiredness
  • decreased skin turgor, which is when you pinch and release your skin, and it does not go back to normal right away
  • sunken eyes or cheeks

If you are experiencing any symptoms of dehydration, contact your doctor or seek medical care right away. Severe cases of dehydration may require hospitalization.

Most people with food poisoning recover without any lasting effects. However, there are other conditions that infections can lead to. These conditions include:

How can you prevent food poisoning?

You can prevent most cases of food poisoning by remembering the four Cs:

  • cleaning
  • cooking
  • chilling
  • (avoiding) cross-contamination

Tips to prevent food poisoning

Some tips to keep in mind when trying to prevent food poisoning include the following:

  • Always keep raw meat, seafood, poultry, and eggs separate from other foods.
  • Prepare any salads and chill them before handling raw meat, seafood, poultry, or eggs.
  • Always refrigerate or freeze foods that can spoil quickly.
  • Always wash your hands with soap and water before and after handling food.
  • Wash fruits and vegetables before eating, cooking, or cutting them.
  • Cook all food at a high enough temperature and for long enough to kill harmful microbes.
  • Always wash your utensils and surfaces after each use.
  • Do not eat food that can spoil if it has been sitting out for longer than 2 hours. If it is above 90ºF (32.2ºC) out, this should be no longer than 1 hour.

Other frequently asked questions

These are some more questions that people have asked about food poisoning.

How long does food poisoning last?

In most cases of food poisoning, the symptoms pass within a few days to 1 week after onset.

What is the fastest acting food poisoning?

Food poisoning that results from S. aureus bacteria typically has the fastest onset of symptoms. The symptoms can begin within 30 minutes to 8 hours after exposure to the bacteria.

These bacteria are most often found in foods that are not cooked after you handle them, such as sliced meats, sandwiches, and pastries.


Food poisoning is an illness that results from bacteria, viruses, or toxins in food.

You can develop food poisoning if you eat contaminated food. Symptoms typically include nausea, vomiting, and diarrhea.

Most cases of food poisoning clear on their own within a few days. During this time, it is important to keep an eye out for symptoms of dehydration, such as dizziness, a dry mouth, and a lack of urination. If you do experience symptoms of dehydration, seek medical care right away.

You can prevent food poisoning by properly cooking, cleaning, storing, and handling food.

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Medical Reviewer: Jerlyn Jones, MS MPA RDN LD CLT
Last Review Date: 2022 Jun 23
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THIS TOOL DOES NOT PROVIDE MEDICAL ADVICE. It is intended for informational purposes only. It is not a substitute for professional medical advice, diagnosis or treatment. Never ignore professional medical advice in seeking treatment because of something you have read on the site. If you think you may have a medical emergency, immediately call your doctor or dial 911.