Medical Dictionary Search Engines

Please be patient! It may take up to ONE minute to load all the Engines.
Problems? Please contact our support.


Search For


Specialty Search




Other encyclopedia topics: A-Ag Ah-Ap Aq-Az B-Bk Bl-Bz C-Cg Ch-Co Cp-Cz D-Di Dj-Dz E-Ep Eq-Ez F G H-Hf Hg-Hz I-In Io-Iz J K L-Ln Lo-Lz M-Mf Mg-Mz N O P-Pl Pm-Pz Q R S-Sh Si-Sp Sq-Sz T-Tn To-Tz U V W X Y Z 0-9   

Food poisoning


Food poisoning is the result of eating organisms or toxins in contaminated food. Most cases of food poisoning are from common bacteria like Staphylococcus or E. coli .

Causes, incidence, and risk factors

Food poisoning can affect one person or it can occur as an outbreak in a group of people who all ate the same contaminated food.

Even though food poisoning is relatively rare in the United States, it affects between 60 and 80 million people worldwide each year and results in approximately 6 to 8 million deaths.

Food poisoning tends to occur at picnics, school cafeterias, and large social functions. These are situations where food may be left unrefrigerated too long or food preparation techniques are not clean. Food poisoning often occurs from undercooked meats or dairy products (like mayonnaise mixed in coleslaw or potato salad) that have sat out too long.

Food poisoning can be caused by:

  • Staph aureus
  • E. coli enteritis
  • Salmonella
  • Shigella
  • Campylobacter
  • Cholera
  • Botulism
  • Mushroom poisoning
  • Listeria
  • Bacillus cereus
  • Fish poisoning
  • Yersinia

Infants and elderly people have the greatest risk for food poisoning. You are also at higher risk if you have a serious medical condition, like kidney disease or diabetes, a weakened immune system, or you travel outside of the U.S. to areas where there is more exposure to organisms that cause food poisoning. Pregnant and breastfeeding women have to be especially careful.


The symptoms from the most common types of food poisoning generally start within 2 to 6 hours of eating the food responsible. That time may be longer (even a number of days) or shorter, depending on the toxin or organism responsible for the food poisoning. The symptoms include:

  • Nausea and vomiting
  • Abdominal cramps
  • Diarrhea (may be bloody)
  • Fever and chills (may not be present)
  • Weakness (may not be present, or may be serious and lead to respiratory arrest in the case of botulism)
  • Headache (may not be present)
Botulism is a very serious form of food poisoning that can be fatal. It can come from improper home canning

Signs and tests

Your healthcare provider will examine you for signs and symptoms of food poisoning, such as stomach problems and dehydration. Your provider will also ask about foods you have eaten recently. Tests of your vomit, blood, stool, and any leftover food may identify the cause. Even if you have food poisoning, however, these tests may not be able to verify it.


You will usually recover from the most common types of food poisoning within a couple of days. The goal is to make you feel better and avoid dehydration . Drink any fluid (except milk or caffeinated beverages) to replace fluids lost by diarrhea and vomiting. Children should be given an electrolyte sold in drugstores. Don't eat solid foods until the diarrhea has passed, and avoid dairy, which can worsen diarrhea.

If you have diarrhea and are unable to drink fluids (for example, due to nausea or vomiting), you may need medical attention and intravenous fluids. This is especially true for young children. If you take diuretics, you need to manage diarrhea carefully. Talk to your doctor -- you may need to stop taking the diuretic while you have the diarrhea. Medications should NEVER be stopped or changed without discussing with your doctor and getting specific instructions.

For the most common causes of food poisoning, your doctor would NOT prescribe antibiotics. Antibiotics can actually prolong diarrhea and keep the organism in your body longer.

If you have eaten toxins from mushrooms or shellfish, you will need to be seen right away. The emergency room doctor will take steps to empty out your stomach and remove the toxin.

Expectations (prognosis)

Full recovery from the most common types of food poisoning usually occurs within 12 and 48 hours. Serious complications can arise, however, from certain types of food poisoning.


Dehydration is the most common complication. This can occur from any of the causes of food poisoning.

Less common but much more serious complications include:

  • Respiratory distress, including the need for support on a breathing machine (botulism)
  • Kidney problems (Shigella, E. coli)
  • Bleeding disorders (E. coli and others)
  • Arthritis (Yersinia and Salmonella)
  • Nervous system disorders (Botulism, Campylobacter)
  • Pericarditis (Salmonella)
  • Death -- 50% of people with mushroom or certain fish poisonings (like puffer fish) die and 10% with botulism

Calling your health care provider

Call your doctor if:

  • You have diarrhea and are unable to drink fluids due to nausea or vomiting.
  • You are on diuretics and have diarrhea, nausea, or vomiting.
  • Diarrhea lasts for more than 2 to 3 days.
  • There is blood in your stools .

Call 911 if:

  • You have signs of dehydration (thirsty, dizzy, lightheaded, faint).
  • Bleeding is excessive or your stools are maroon or black.
  • You are short of breath or having trouble breathing.
  • Your heart is racing, pounding, or skipping.
  • You may have poisoning from mushrooms, fish, or botulism.
  • You have any nervous system symptoms like weakness, double vision, difficulty speaking, or paralysis.
  • You have a fever over 101°F.
  • You have trouble swallowing.


To prevent food poisoning, take the following steps when preparing food:
  • Carefully wash your hands and clean dishes and utensils.

    Update Date: 8/8/2003

    Jacqueline A. Hart, M.D., Senior Medical Editor, A.D.A.M.,Inc. Previously reviewed by Steven Angelo, M.D., Assistant Professor of Medicine, Yale School of Medicine, New Haven, CT. Review provided by VeriMed Healthcare Network (1/12/2003).

©2009 [Privacy Policy] [Disclaimer]
Last updated: Tue, 06 Jan 2009 00:20:03 GMT