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Symptoms and Signs of Food Poisoning vs. Stomach Bug: Comparison of Differences

Doctor's Notes on Food Poisoning vs. Stomach Bug: Comparison of Differences

Food poisoning is an illness caused by eating or drinking contaminated food or water; the contaminants can be viruses, bacteria, toxins, parasites or chemicals. The stomach flu (gastroenteritis) is a general term used for various inflammatory problems in the digestive tract, some of which can include food poisoning causes. The most common food poisoning symptoms and signs are abdominal cramps, nausea, vomiting, and diarrhea. More severe food poisoning symptoms may include blood in the stool or vomit, dehydration, high fevers, diarrhea the last for three days, headaches, weakness, blurry vision, bloating, the problems, renal problems and numbness tingling or burning sensation to the extremities, seizures and death. Signs and symptoms of gastroenteritis include low-grade fevers, nausea without vomiting, mild to moderate diarrhea, crampy abdominal bloating, most of which are less severe than those for food poisoning. However, more serious symptoms can occur such as blood in vomitus or stools, vomiting more than 48 hours, fever high than 101F, swollen abdomen with increasingly severe abdominal pain and dehydration. Most causes of food poisoning last from a few hours to a few days while gastroenteritis last from 1 to 2 days to months.

Viruses are the most frequent cause of food poisoning in the US; the next highest causes are bacteria while other causes include chemicals, parasites and toxins. Viruses cause about 70% of gastroenteritis problems and bacterial infections cause most of the rest.

Medical Author:
Medically Reviewed on 3/20/2019

Food Poisoning vs. Stomach Bug: Comparison of Differences Symptoms

Food Poisoning Symptoms and Signs

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

  • Abdominal cramps
  • Nausea
  • Vomiting
  • Diarrhea

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

Symptoms of food poisoning sometimes depend on which organ system the poison effects; 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.

Stomach Flu Symptoms and Signs

By definition, gastroenteritis affects both the stomach and the intestines, resulting in vomiting and diarrhea. Other symptoms and signs include:

  • Low grade fever, usually less than 100 F (37.7 C)
  • Nausea with or without vomiting
  • Mild-to-moderate diarrhea (Dehydration also can intensify the symptoms of nausea and vomiting.)
  • Crampy painful abdominal bloating (The cramps may come in cycles, increasing in severity until a loose bowel movement occurs and the pain re resolves somewhat leaving a dull ache.)

More serious signs and symptoms of stomach flu (gastroenteritis)

  • Blood in vomit or stool (this is never normal and the affected individual should seek immediate medical care)
  • Vomiting more than 48 hours
  • Fever higher than 101 F (40 C)
  • Swollen abdomen
  • Increasingly severe abdominal pain
  • Dehydration - weakness, lightheadedness, decreased urination, dry skin, dry mouth and lack of sweat and tears are characteristic symptoms of dehydration.

If symptoms continue or worsen, call a health-care professional. Diarrhea is one of the leading causes of infant sickness and death. Worldwide, diarrhea accounts for 3-5 million deaths yearly for all age groups. In general, most adults and children recover after they are appropriately rehydrated.

Food Poisoning vs. Stomach Bug: Comparison of Differences Causes

Viruses are the most frequent cause of food poisoning in the U.S. The next highest causes are bacteria. Other causes include chemicals, parasites, toxins, and bacteria.

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

Gastroenteritis or the stomach flu can spread from person to person because of improper hand-washing following a bowel movement or handling a soiled diaper.

Uncommon and Common Food-Poisoning Dangers in Pictures Slideshow

Uncommon and Common Food-Poisoning Dangers in Pictures Slideshow

Listeria bacteria can contaminate fresh produce, like cantaloupes, as well as some processed foods, like cheeses. Symptoms of infection include fever, muscle aches, upset stomach, or diarrhea -- occurring 2 days to 2 months after exposure.

Safety: Scrub raw produce and dry before cutting. Store in fridge below 40 F. Clean everything in contact with a whole melon.


Kasper, D.L., et al., eds. Harrison's Principles of Internal Medicine, 19th Ed. United States: McGraw-Hill Education, 2015.