Food poisoning refers to illness brought on by ingesting foods contaminated with living microorganisms, toxins produced by microorganisms, poisonous chemicals, or poisonous fish, shellfish, or plants (such as mushrooms). The digestive tract is most commonly affected. However, botulism, a life-threatening form of food poisoning, primarily affects the nervous system and may cause respiratory failure.

Food poisoning may result from improper storage and handling of food, such as inadequate refrigeration or touching food with soiled hands or machinery. Symptoms generally develop within one to 48 hours after eating. Some types of food poisoning (notably cholera and shigellosis) may take from three to five days to produce symptoms.

Food poisoning is suspected when sudden, acute gastrointestinal symptoms arise. It is difficult to prove that food poisoning is the cause of illness unless several people develop symptoms after sharing a meal or after eating in the same restaurant. The illness often subsides spontaneously after one to five days; however, severe or persistent symptoms require treatment and sometimes hospitalization.

What Causes Food Poisoning?

  • Preformed bacterial toxins produced by overgrowth of certain bacteria before food is eaten.
  • Contamination with live microorganisms that proliferate in the intestine and may invade tissues or produce toxins.
  • Poisonous metals
  • Poisons in fish, shellfish, and plants (mushrooms)

Symptoms of Food Poisoning

  • Diarrhea that may contain blood
  • Abdominal pain and cramps, nausea and vomiting
  • Feeling that the heart is pounding
  • Loss of appetite
  • Trouble breathing
  • Difficulty swallowing
  • Weakness and fatigue
  • Double vision
  • Trouble moving parts of your body
  • Fever
  • Headaches
  • Bloody stool

Preventing Food Poisoning

  • Wash your hands thoroughly with warm water and soap before preparing food.
  • Make sure food is handled, cleaned, cooked, and refrigerated properly.
  • Don’t buy or use food in cans that are rusty, bulging, dented, or leaking.
  • Avoid tasting food to check for contamination.
  • Don’t eat mushrooms you have picked.
  • Don’t consume unpasteurized dairy products.
  • Throw away any questionable leftovers.

Diagnosis of Food Poisoning

  • Vomit, feces, or blood may be cultured or tested.
  • If available, samples of suspected foods are examined for contaminants.

How to Treat Food Poisoning

  • Diarrhea may help rid the body of bacteria and toxins. For that reason, check with your doctor before taking antidiarrheal medications.
  • Avoid eating solid food until the diarrhea has passed.
  • Drink plenty of fluids to prevent dehydration from diarrhea.
  • A drink containing electrolytes and sugar may be needed to replace minerals lost with severe diarrhea.
  • Intravenous fluids may be needed to treat severe dehydration.
  • Medication to prevent vomiting (antiemetics) may be prescribed in severe cases, although vomiting may help rid the body of toxins.
  • Antibiotics may be prescribed in some cases, if certain infectious agents are involved.

According to the National Institutes of Health (NIH) in June 2015, antibiotic-resistant infections from food-borne microorganisms cause about 400,000 cases of food poisoning each year in the United States. This resistance is a serious public health threat, resulting primarily from the overuse of antibiotics, and increasing the risk for severe infections.

When to Call a Doctor

  • The elderly, young children, and anyone with a weakened immune system (such as those diagnosed with AIDS or undergoing treatment for cancer) should be taken to a doctor immediately if they develop even mild symptoms of food poisoning. These people are at greater risk of life-threatening complications.
  • Call a doctor if you develop any of the following: sudden, severe or bloody diarrhea; a fever over 102°F; severe abdominal pain.
  • Call a doctor if food poisoning symptoms do not subside within a week.


Johns Hopkins Symptoms and Remedies: The Complete Home Medical Reference

Simeon Margolis, M.D., Ph.D., Medical Editor

Prepared by the Editors of The Johns Hopkins Medical Letter: Health After 50

Updated by Remedy Health Media

Publication Review By: the Editorial Staff at

Published: 22 Aug 2011

Last Modified: 22 Jun 2015