Food Poisoning

Reviewed on 11/1/2022

What to Know About Food Poisoning

Picture of Batteria in Food
Picture of Batteria in Food
  • Food poisoning is a disease that usually results in vomiting and diarrhea after a person eats or drinks fluids contaminated with certain bacteria, viruses, parasites, or chemicals (toxins).
  • The most common symptoms and signs of food poisoning are vomiting and diarrhea.
  • Other symptoms that may occur are fever, abdominal pain, and/or cramps.
  • Severe signs and symptoms may include dehydration, blood in vomit or stools, diarrhea over 3 days, and neurologic symptoms; for example, weakness, blurry vision, and an abnormal sensation of the body such as burning, tingling, or numbness (paresthesias).
  • Causes include many things including viral and bacterial strains, parasites, and chemicals (toxins). If the cause is not contaminated food, it most likely is contagious.
  • Depending on the cause of food poisoning, the duration of the majority of food poisoning usually ranges from a few hours after exposure to contaminated food or fluid to several days.
  • Treatment of food poisoning depends on the cause; most people self-care in a few days, but some cases may benefit from specific antibiotic or antiparasite treatments once the cause is identified.
  • Home remedies to soothe food poisoning symptoms may help speed recovery and may include:
    • Rest
    • Rehydration
    • Slowly begin to eat bland foods like rice, bananas, toast, gelatin
    • Avoid alcohol, nicotine, fatty, and seasoned or spicy foods)

What Is Food Poisoning?

Food poisoning is an illness caused by eating or drinking food or water contaminated with viruses, bacteria, toxins, parasites, or chemicals. Typical symptoms of food poisoning are vomiting and diarrhea.

What Are the Signs and Symptoms of Food Poisoning?

The most common signs and symptoms of food poisoning from most causes are as follows:

  • Abdominal cramps
  • Nausea
  • Vomiting
  • Diarrhea

However, symptoms of infrequently can get worse. Other serious symptoms include:

  • Blood in the stool or vomit
  • Dehydration
  • High fevers
  • Diarrhea that lasts more than 3 days
  • Headaches
  • Weakness
  • Blurry vision
  • Numb, tingling, or burning sensations in the extremities
  • Bloating
  • Liver problems
  • Renal problems
  • Reactive arthritis
  • Seizures
  • Death

Symptoms of food poisoning sometimes depend on which organ system the poison affects; for example, the neurological system may be altered by neurotoxins like pesticides and botulinum toxin.

When a group of individuals experiences similar symptoms after eating or drinking similar foods, food poisoning may be suspected.

Some people are at higher risk to develop food poisoning. They include children, older adults, pregnant women and people with medical conditions like diabetes, liver disease, kidney disease and anyone with immunodepression.

What Are Different Types of Food Poisoning and Causes?

Viruses and bacteria

Viruses are the most frequent cause of food poisoning in the U.S. The next highest causes are bacteria. About 31 viral and bacterial pathogens are responsible for almost 9.4 million diagnosed food poisoning illnesses per year; about 48 million food poisoning cases are unspecified (undiagnosed). Yearly, about 128,000 people are hospitalized and about 3,000 die from all causes of food poisoning.

The most common pathogens that cause food poisoning are:

The most common pathogens that caused hospitalizations due to contamination of foods or fluids are:

The most common pathogens that cause deaths are:

  • Salmonella
  • Toxoplasma gondii
  • Listeria monocytogenes
  • Norovirus
  • Campylobacter

Infectious agents comprise the largest category of food poisoning, but as seen from the above top categories, viral infections comprise the bulk of infected patients but are far less likely to cause hospitalizations and deaths than Salmonella bacteria. Because the bulk of "unspecified" causes is probably similar to the makeup of the diagnosed causes, this grouping of viruses and bacteria is considered to be the main causes of food poisoning in the U.S.


There are many toxins that can cause food poisoning. Some are produced by bacteria on or in food and others are produced by plants and animals/fish or other organisms that are ingested. There are many plants and animals/fish that can be poisonous under certain conditions but they are encountered infrequently or under special conditions.

Various toxins and their sources
Bacteria Plants Animals/fish/other
enterotoxins Mushroom toxins Scombroid toxin
exotoxins Belladonna Ciguatera toxin
cytotoxins Ricin Saxitoxin
neurotoxins Hemlock Tetrodotoxin

Even though there are many bacterial, plant, and other toxins that can be ingested with food and water, they are usually limited to relatively small outbreaks.


Most parasites are ingested with contaminated food or water. Some of the parasites ingested include:

  • Giardia
  • Amoeba
  • Trichinella
  • Taenia solium


Certain chemicals are considered toxins that can cause food poisoning. Although there are over 80,000 chemicals used in the U.S., only a few have been well studied. While most do not enter into foods, some do and cause food poisoning. An example of such a chemical is mercury, found in drinking water and in fish such as tuna and marlin. Other examples of chemicals that can be toxic if enough contaminates food and water are pesticides, polychlorinated biphenyls, and lead.

The causes of food and water poisoning are numerous. This brief listing of causes should suffice as a framework to begin more detailed studies of food poisoning.

If viruses or bacteria cause food poisoning, it can be contagious.

What Foods Cause Food Poisoning?

Foods most commonly associated with food poisoning include:

  • Eggs
  • Poultry
  • Meats
  • Unpasteurized milk or other fluids
  • Cheese,
  • Raw fruits and vegetables (usually unwashed
  • Nuts
  • Spices

How Long Does Food Poisoning Last?

In the majority of individuals with mild to moderate symptoms of food poisoning (viral and bacterial), symptoms resolve in about 24-48 hours and no specific medical treatment is needed. However, if there are any signs of dehydration (decreased or no urination, dry mouth, increased thirst, dizziness, and weakness), blood in the stools, fever, vomiting, or diarrhea longer than 72 hours, medical care should be sought. If there is any reason to suspect that a rarer cause of food poisoning is causing symptoms, see a doctor.

How Is Food Poisoning Diagnosed?

The diagnosis usually begins with the patient's recent history of eating foods or exposure to contaminated water, travel history, and questions about friends or relatives with similar symptoms. The physical exam will focus on signs of dehydration and abdominal tenderness, while blood tests, if necessary, may be used to help rule out other problems.

Stool samples may be useful to detect blood in the stool, culture for pathogens, microscopically examine for parasites and to detect certain toxins. In addition, there are immunological tests for some toxins (for example, Shiga toxin). Depending on the suspected cause, in rare cases, biopsy samples may be taken. Definitive diagnosis depends on the identification of the pathogen or toxic material found in the individual.

Although tests are available, in mild to moderate cases of viral and most bacterial food poisoning, tests are not usually done because of the expense and the likelihood that symptoms will resolve before the tests are completed.

What Is the Treatment for Food Poisoning?

Treatment of food poisoning is mainly done with fluids to avoid dehydration, especially in children and the elderly.

Some patients may benefit from medication to reduce nausea and vomiting. The use of medications like loperamide (Imodium) to treat diarrhea is often not advised as it may prolong symptoms or cause additional problems. Patients are advised to check with their doctor before using the medication. Antibiotics are not used to treat viral and most bacterial causes of food poisoning but may be used in certain circumstances.

Severe bacterial infections and pregnant women with listeriosis will get antibiotics; some other pathogens such as certain parasites may be treated with antiparasitic medications. Other relatively rare causes of food poisoning may require special medications.

What Type of Diet Should I Eat After Food Poisoning?

Home care for mild to moderate bacterial and viral food poisoning is mainly preventing dehydration.

  • Fluid replacement by mouth using a combination of water and electrolyte solutions like Gatorade or Pedialyte is usually enough to avoid dehydration as long as enough is taken to replace the amount lost through diarrhea.
  • Infrequent or rare cases of food poisoning should be treated by a doctor or a specialist; this should also be done in severe viral and bacterial cases of food poisoning.

Do I Need to See a Doctor for Food Poisoning?

Although many people require no physician to intervene, a primary care physician often can treat some types of food poisonings. However, more serious types are often treated by a team that may include specialists in infectious diseases, gastroenterology, critical care, and/or toxicology.

How Do I Know If I Have Food Poisoning or the Stomach Flu?

Gastroenteritis (stomach flu) is defined as an infection or irritation of the gastrointestinal tract, especially the stomach or intestines. It is a slightly more specific term that describes a particular type of food poisoning. However, the term is used most often to describe stomach irritation or inflammation due to infection, including non-food-related infections.

How Can Food Poisoning Be Prevented?

Prevention of food poisoning is possible. The Centers for Disease Control (CDC) published ways to prevent food poisoning and included links to videos:

  • CLEAN: Wash your hands and surfaces often. Germs can survive in many places around your kitchen, including your hands, utensils, and cutting boards.
  • Rinse fresh fruits and vegetables under running water and always follow the rules of food safety.
  • SEPARATE: Don't cross-contaminate. Even after you've cleaned your hands and surfaces thoroughly, raw meat, poultry, seafood, and eggs can still spread germs to ready-to-eat foods—unless you keep them separate. Watch the SEPARATE video!
  • COOK: Cook to the right temperature. While many people think they can tell when food is "done" simply by checking its color and texture, there's no way to be sure it's safe without following a few important but simple steps. Use a food thermometer to ensure that foods are cooked to a safe internal temperature: 145 F (62.77 C) for whole meats (allowing the meat to rest for 3 minutes before carving or consuming), 160 F (71.11 C) for ground meats, and 165 F (73.89 C) for all poultry. Watch the COOK video!
  • CHILL: Keep your refrigerator below 40 F (4.44 C) and refrigerate foods properly. Germs can grow in many foods within 2 hours unless you refrigerate them. (During the summer heat, cut that time down to 1 hour.)

When traveling in foreign countries, especially developing countries, it is best to wash any fruits or vegetables before eating and only drink from commercially sealed bottles. The use of ice in drinks is not recommended.

What Is the Outlook for a Person With Food Poisoning?

Most cases of food poisoning in the U.S. have good outcomes because they usually resolve quickly and have no complications. However, in some instances, a person may have severe symptoms and the outcome may range from good to poor, depending on the person's food poisoning agent and their response to treatment.

The prognosis for common food poisoning (viral, bacterial) in developing countries is guarded especially for children and the elderly as they often have other health conditions that weaken them and sometimes have little or no access to pathogen-free foods or water.

Salmonella infection

Food Poisoning Symptoms

Symptoms of Salmonella Infection

The symptoms of Salmonella infections depend on the overall health of the infected person (for example, normal or with a suppressed immune system) and the particular serovar infecting the patient. Symptoms usually begin about 12-72 hours after ingestion of the bacteria. In general, people contract S. spp (for example, serovars S. enteritidis, S. cholerasuis) that usually cause a self-limiting diarrhea, nausea, and vomiting termed salmonellosis or S. gastroenteritis.

Reviewed on 11/1/2022

CDC. "Food Safety." Updated: Feb 07, 2018.

CDC. Be Food Safe: Protect Yourself from Food Poisoning. Updated: Apr 18, 2017.

CDC. "Estimates of foodborne illness in the U.S.". Aug 19, 2016.

Gamarra, R. "Food Poisoning." Medscape. Jun 26, 2015,