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Food poisoning: Everything thing you need to know

Gastroenteritis is a condition that involves inflammation of the gut lining– particularly of the stomach and intestines. This usually recovers without treatment but can lead to complications in some cases.

Food poisoning is a major cause of gastroenteritis leading to a common series of unpleasant symptoms.

Gastroenteritis is usually caused by viruses, bacteria, or parasites; this is called food poisoning when the source of the infection is contaminated food. Gastroenteritis could also be called “gastric flu” or “stomach flu.”

Fast facts on gastroenteritis and food poisoning

Here are some key points about food poisoning and gastroenteritis. More detail and supporting information is in the body of this article.

  • Most cases of gastroenteritis are caused by infection with bacteria, viruses, or parasites
  • Diarrhea, nausea, vomiting, and abdominal pain are typical symptoms of gastroenteritis
  • Gastroenteritis is usually self-limiting, and tests are not usually necessary for a diagnosis
  • The most serious complication of food poisoning and gastroenteritis is dehydration, especially for vulnerable people such as the very young and very old


Drinking plenty of liquids can help treat dehydration.
Drinking plenty of liquids can help treat dehydration.

Gastroenteritis and food poisoning normally resolve without medical intervention. Treatment focuses on reducing the symptoms and avoiding complications, particularly dehydration.

The main strategy for food poisoning treatment and prevention is to rest and replace the lost fluids and electrolytes with:

  • Drinking plenty of liquids (preferably with oral rehydration salts to replace lost electrolytes – see below)
  • Ensuring fluid intake even if vomiting persists, by sipping small amounts of water or allowing ice cubes to melt in the mouth.
  • Gradually starting to eat again. No specific restrictions are recommended, but blander foods might be easier to start with (cereal, rice, toast, and bananas are good examples).

During episodes of gastroenteritis, the following can exacerbate symptoms: fatty, sugary or spicy foods, dairy products, caffeine, and alcohol.

To prevent the dangerous and potentially lethal effects of diarrhoea dehydration, oral rehydration salts (ORS) are recommended for vulnerable people (such as infants and children, adults over the age of 65 and people with reduced immunity).

According to a former director-general of the World Health Organization (WHO), Dr. Gro Ver Brundtland, the use of ORS in developing countries has been “one of the great public health success stories of our time,” reducing the number of deaths annually among children with acute diarrhea from 5 million to 1,3 million deaths.

While the threat of death is lower in developed countries, rehydration is nevertheless important.

Salt, glucose, and minerals lost through dehydration are replaced by sachets of oral rehydration salts available from pharmacies. The salts are dissolved in drinking water and do not require a doctor’s prescription.

Getting the right concentration is crucial, as too much sugar can make diarrhea worse, while too much salt can be extremely harmful, especially for children. A more diluted solution (using more than 1 liter of water, for example), is preferable to a more concentrated one.

In addition, store-bought products such as Pedialyte and Gatorade help restore electrolytes and increase hydration.

Drug treatments for gastroenteritis

Drugs are available to alleviate gastroenteritis ‘ main symptoms– diarrhea and vomiting:

  • Antidiarrheal medication such as loperamide (branded versions include Imodium, and Imotil, among others) and bismuth subsalicylate (for example, Pepto-Bismol)
  • Antiemetic (anti-vomiting) medication such as chlorpromazine and metoclopramide

Antidiarrheals are available OTC, while antiemetics are available from doctors.

Talk to a doctor before taking medication for anti-diarrhea as some infections that get worse with anti-diarrhea medicines.

Probiotics and gastroenteritis

Probiotics (live “healthy” bacteria and yeasts) may also be useful in the treatment of gastroenteritis, some more recent research suggest. One study found the use of probiotics for acute gastroenteritis in hospitalized children reduced their hospital stay by an average of 1.12 days.

In particular, some evidence exists to support the use of the following strains of beneficial bacteria in the treatment of gastroenteritis in infants, in addition to the use of oral rehydration solutions without dietary restriction:

  • Lactobacillus rhamnosus GG
  • Saccharomyces boulardii

This is a new area of study so in the future there may be more work on using probiotics for the treatment of gastroenteritis.


Abdominal cramps can be a symptom of gastroenteritis.
Abdominal cramps can be a symptom of gastroenteritis.

Four well-known, classic symptoms are typical of gastroenteritis:

  • Diarrhea (loose stools)
  • Nausea (feeling sick or queasy)
  • Vomiting
  • Abdominal pain (‘stomach cramps’)

Such symptoms can arise in any combination; they typically have a sudden (acute) onset but this and the severity of the symptoms can differ.

The onset of symptoms after consuming contaminated food may be within a few hours, but depending on the pathogen involved, the incubation period may be much longer too.

Vomiting usually occurs in the disease earlier, diarrhea usually lasts for a few days, but may be longer depending on the organism that causes the symptoms.

Food poisoning and gastroenteritis can also cause, in addition to the classic symptoms above:

  • Loss of appetite
  • Fever or high temperature and chills

The type of gastrointestinal symptoms is an indicator of the type of infection — viral infection usually results in diarrhea without blood or mucus, and watery diarrhea is the predominant symptom. Conversely in bacterial diarrhea, mucus and blood are more frequently seen. Norovirus has the potential to cause acute vomiting, especially in children.

One of the dangers of food poisoning and gastroenteritis is the loss of fluids resulting from diarrhea and vomiting, which can lead to dehydration, particularly in very young, elderly, or otherwise vulnerable persons. However, it can prevent dehydration.

Individuals may seek medical care if they get lightheaded, have bloody diarrhea, fevers, are over 65, have multiple medical issues, are pregnant, or if symptoms aren’t getting better in a couple of days.

Food poisoning or stomach flu?

Food poisoning and stomach flu have similar symptoms but a virus, such as the norovirus, also triggers stomach flu.


The time taken to show up with symptoms depends on the bacteria or pathogen involved.

The US Food and Drug Administration (FDA) states:

  • Bacillus cereus: Present in meats, stews, and gravies, it takes 10 to 16 hours to trigger symptoms, and they last for 24 to 48 hours.
  • Campylobacter jejuni: Present in undercooked poultry, symptoms appear after 2 to 5 days and last for 2 to 10 days.
  • E. coli O157:H7: Present in undercooked beef, contaminated water, and others, symptoms appear after 1 to 8 days and last 5 to 10 days.

Different pathogens will have different effects on the body. See the FDA website for more details.


The United States Food and Drug Administration (FDA) cites that, despite high U.S. food supply requirements, nearly 48 million cases of foodborne illness occur annually due to contaminated food.

The FDA reports that the food poisoning would result in 128,000 hospitalizations and 3,000 deaths.

The organization, along with a summary of the symptoms usually caused by each of these diseases, provided a complete list of the microorganisms responsible for these illnesses.

In general terms, gastroenteritis is caused by three types of infectious agents:

  • viruses
  • bacteria
  • parasites

The viruses that are most commonly implicated in gastroenteritis are:

  • Rotavirus: More common in children and the most common cause of viral gastroenteritis in children
  • Norovirus: More common in adults

Astrovirus, which usually affects children and the elderly, and adenoviruses are the less common viral causes. Cytomegalovirus can lead to gastroenteritis, especially in those with compromised immunity.

The most often involved bacteria in gastroenteritis are:

  • Salmonella
  • Campylobacter
  • Shigella
  • Escherichia coli (especially serotype O157:H7)
  • Clostridium difficile

A Research from the United States The Interagency Food Safety Analytics Partnership of Centers for Disease Control and Prevention found 46 percent of E from 2008 to 2012. Coli cases came from beef, 18% of salmonella cases came from planted vegetables and 66% came from dairy products.


Gastroenteritis is typically easy to diagnose from the symptoms alone, with little need for a doctor’s confirmation; patient-reported symptoms are usually sufficient to notify a diagnosis.

Stool testing is necessary in some cases. Of example, if blood follows diarrhea or is watery for more than a couple of days, doctors may want a sample to check for parasites or bacteria.

Similar tests may also be required during an outbreak of, for example, rotavirus.


Kitchen hygiene is the key to preventing food poisoning.
Kitchen hygiene is the key to preventing food poisoning.

Standard advice to avoid food poisoning includes four key components:

  • Cook: Ensure adequate heating time at the proper temperature to kill any bacteria that could cause gastroenteritis. It is helpful to use a thermometer to test cooked meat and to ensure egg yolks are firm.
  • Separate: Separate foods to avoid cross-contamination, and especially raw meat.
  • Chill: Chilled storage slows the growth of harmful bacteria.
  • Clean: Keep utensils and worktops clean and wash hands frequently, especially before eating or touching the mouth and after handling raw meat or eggs

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