Gastroenteritis: how to treat stomach flu?
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Gastroenteritis is an infection of the digestive tract, very common in children. Most often of viral origin, it is mainly transmitted through dirty hands, water, and food.

What are the symptoms? What are the precautions to take to protect yourself? How to treat it? Here are our explanations.

What is gastroenteritis?

Gastroenteritis is an infection of the digestive system that causes:

  • Nausea;
  • Vomiting;
  • abdominal cramps;
  • diarrhea.

In the majority of cases, it is short-lived. Symptoms occur quickly and usually disappear within 1 to 3 days.

Gastroenteritis has multiple causes. This may include:

  • different viruses;
  • bacteria;
  • other microorganisms such as amoebas.

These are mainly transmitted by:

  • hands;
  • water;
  • contaminated food.

The intensity and duration of symptoms vary depending on the cause. Viral gastroenteritis is by far the most common, accounting for more than two-thirds of cases.

Viruses involved

Many viruses can cause gastroenteritis.

In adults, norovirus or calicivirus is recognized as the agent most often involved in outbreaks of viral gastroenteritis. The best known of these is the Norwalk virus, first identified in 1968 in a school in Norwalk, USA, during an outbreak of gastroenteritis.

As for rotavirus, it is the type of virus most frequently responsible for gastroenteritis in young children, occurring in more than half of cases.

Gastroenteritis: the bacteria involved

There is also gastroenteritis that is caused by bacteria such as:

  • Salmonella;
  • Campylobacter;
  • Shigella;
  • Coli;
  • Vibrio;
  • Yersinia ;
  • Clostridium difficile.

The parasites involved

Parasites can also be involved such as:

  • amoeba;
  • Giardia;
  • Cryptosporidium.

Travelers’ diarrhea

Travelers’ diarrhea can occur in about half of the visitors who visit:

  • in Asia excluding Singapore;
  • on the African continent except for South Africa;
  • in Central and South America.

It is caused by:

  • water;
  • food contaminated, most commonly with E Coli, then Salmonella, Campylobacter, and Shigella.

It occurs 4 to 14 days after arrival. It usually lasts from 1 to 5 days.

It is estimated that about one in five cases of gastroenteritis is caused by bacterial food poisoning. Three mechanisms can be at work.

Ingestion of food contaminated with a toxin

Some bacteria, such as staphylococcus or bacillus Cereus, produce a toxin in food before it is consumed. This toxin is heat resistant. The incubation period is 1-6 hours, and the disease lasts about 24 hours.

Ingestion of food contaminated with bacteria

The bacteria involved, such as C Perfringens or toxogenic E coli, produce a toxin once they are in the gut.

Ingestion of food contaminated with bacteria that can enter the lining of the intestine

In this case, ingestion of these foods can cause inflammatory diarrhea due to:

  • enterohaemorrhagic coli;
  • Salmonella;
  • Shigella;
  • Vibrio.

Some antibiotics can cause Clostridium difficile gastroenteritis. This gastroenteritis can be very severe and fatal, especially in the elderly or weakened by an illness. This is one of the reasons why antibiotics should not be taken without a valid reason.

Mode of transmission of gastroenteritis

Gastroenteritis is contracted through one of two routes.

Food poisoning

This is called bacterial gastroenteritis. Eating food or water contaminated with germs can cause gastroenteritis. The foods that carry it most often are, in order of importance:

  • seafood;
  • poorly washed fruits and vegetables;
  • poultry;
  • beef;
  • eggs.

By contact with a contaminated person or object

This is called viral gastroenteritis. This is the so-called “oral-fecal” pathway. The disease can be contracted if, after touching a contagious person or contaminated objects or surfaces, you put your hands to your face or prepare a meal without washing your hands thoroughly. An affected person is contagious from the time symptoms begin until about 48 hours after they disappear.

List of foods that can cause food poisoning

Foods that can cause food poisoning include:

  • undercooked ground beef contaminated with E. coli 0157:H7. This type of poisoning is called hamburger disease or barbecue syndrome;
  • green leafy vegetables contaminated with E. coli 0157:H7;
  • eggs contaminated with Salmonella bacteria;
  • water or food contaminated with Norwalk virus;
  • fruit contaminated with enterotoxigenic E. coli or ETEC in a country with poor sanitary conditions;
  • poisonous mushrooms.

Hygiene in the food chain

Hygiene measures and inspections implemented by the food industry make it possible to eliminate a large part of the germs that may be present in the food chain.

The consumer is also a very important link in the chain because the stages of food preparation and cooking also help to eliminate germs. Refreezing a thawed product or breaking the cold chain at any of the steps can, for example, cause harmful microorganisms to grow.

Prevalence of gastroenteritis

Every year, outbreaks of gastroenteritis affect millions of people worldwide, especially children.

In Canada, as in Europe or the United States, there is an upsurge in viral gastroenteritis during the winter.

Norovirus causes the majority of gastroenteritis outbreaks at any age. It causes severe vomiting and lasts from 12 to 60 hours.

Bacterial gastroenteritis occurs in all seasons but is much less common than viral gastroenteritis in industrialized countries.

Several studies conducted in Canada have found that, on average, Canadians suffer from 1.3 gastroenteritis per year, of greater or lesser intensity.

According to studies, it is estimated that 1 in 200 children under 5 years of age to 1 in 80 children is hospitalized each year in developed countries for rotavirus gastroenteritis. In Quebec, 2,000 to 2,500 hospitalizations per year are linked to this disease.

Possible complications of gastroenteritis

Although generally harmless in industrialized countries, gastroenteritis is often fatal in several parts of the world: there are 1.5 to 2.5 million deaths per year from acute diarrhea.

In particular, rotavirus is particularly severe, very often causing dehydration. It particularly affects young children and causes 500,000 deaths per year worldwide.

If gastroenteritis is not managed properly, it can have serious consequences for people of fragile constitutions, due to the dehydration it causes, such as:

  • infants;
  • young children;
  • sick people;
  • the elderly.

Dehydration occurs when the body loses too much fluid and mineral salts, which are essential for the body’s function. A child can become very dehydrated after only 1 or 2 days of diarrhea.

It should be noted that in very rare cases, serious poisoning, particularly E. coli poisoning, can cause kidney damage. These poisonings begin with common symptoms of gastroenteritis, such as diarrhea, but can escalate and lead to death. Gastroenteritis or C difficile colitis can also be very serious and sometimes fatal.

When to consult in case of gastroenteritis?

Seek medical attention as soon as possible if any of the following symptoms occur.

In infants

  • signs of dehydration: severe thirst and dry layers, dark circles and “sunken” in the sockets, dry mouth, absence of tears, fontanelles more marked than usual;
  • blood in the stool, which may be red or black;
  • lethargy or excessive sleep: it is difficult to wake the baby
  • vomiting for several hours;
  • fever above 38.5°C (101.3°F)
  • rapid, panting breathing.

In adults

Remark. Diarrhea and vomiting can interfere with the absorption of medications, which can make them less effective. This is also the case for the contraceptive pill. If in doubt, consult a doctor.
  • vomiting or diarrhea that leads to symptoms of dehydration that cannot be counteracted with a rehydration solution
  • inability to urinate for more than 12 hours;
  • vomiting blood;
  • have blood in the stool
  • severe abdominal pain lasting more than 2 hours;
  • fever of 40°C (104°F) or higher

In healthy adults, symptoms of gastroenteritis usually last 1 to 3 days. Exceptionally, they can persist for up to 7 days. The intensity of symptoms varies depending on the cause, with bacterial gastroenteritis being more severe than viral gastroenteritis.

What are the symptoms of gastroenteritis?

Symptoms of gastroenteritis include:

  • loss of appetite
  • abdominal cramps
  • nausea and vomiting that appear suddenly;
  • very watery diarrhea
  • mild fever: 38°C or 101°F
  • headaches
  • fatigue.

Identifying symptoms of dehydration

Symptoms of gastroenteritis-related dehydration include:

  • dry mouth and skin
  • less frequent urges to urinate;
  • darker than usual urine
  • irritability
  • muscle cramps
  • loss of weight and appetite
  • weakness;
  • hollow eyes;
  • shock;
  • fainting.

Some people are at higher risk of developing gastroenteritis. Also, certain risk factors favor the appearance of this disease.

Gastroenteritis: people at risk

People at risk for gastroenteritis are:

  • Young children, aged 6 months to 3 years, especially those who attend daycares or nurseries because of the multiplication of contacts: are particularly at risk because their immune system is immature and they put everything in their mouth. On average, a child under 5 years of age suffers from diarrhea 2.2 times a year in industrialized countries11;
  • As a result, day-care staff are also more at risk;
  • the elderly, especially those living in residences, with their immune systems weakening with age;
  • people who live or work in closed environments such as hospitals, airplanes, cruise ships, summer camps, etc. Half of them would be likely to contract gastroenteritis when an epidemic breaks out;
  • people traveling in Latin America, Africa, and Asia;
  • People with an immune system weakened by disease or immunosuppressive drugs, such as anti-rejection drugs for transplant patients, certain anti-arthritic drugs, cortisone, or powerful antibiotics that unbalance the intestinal flora.

Gastroenteritis: risk factors

As soon as basic hygiene measures are not observed, there is a risk of contracting gastroenteritis.

To avoid contracting gastroenteritis, there are a number of preventive measures, either to prevent the onset of the disease or to avoid the risk of complications.

How to prevent gastroenteritis?

Basic preventive measures

Preventing person-to-person contamination

To prevent person-to-person contamination, here are our tips to follow:

  • wash your hands and your child’s hands regularly with soap and water, especially before eating, before preparing meals, after going to the toilet, and after changing a diaper.
  • Wash clothes soiled by diarrhea or vomiting thoroughly;
  • clean any objects soiled by diarrhea or vomiting with bleach, especially toilets and sinks;
  • do not share utensils or food with anyone who has gastroenteritis;
  • do not share bath towels;
  • store toothbrushes separately;
  • Avoid direct contact with a person who has gastroenteritis as much as possible.

Preventing food poisoning

To prevent food poisoning, you should:

  • cook food thoroughly, especially red meat, poultry, and eggs;
  • refrigerate leftovers within 2 hours of cooking;
  • rinse fruits and vegetables that are eaten fresh with tap water;
  • Do not cook on a surface that has come into contact with raw meat or poultry;
  • use one board to cut raw meat and another for vegetables;
  • thoroughly clean kitchen utensils after use;
  • eat pasteurized dairy products preferably. Pasteurization kills microbes through heat;
  • ensure that the temperature of the refrigerator does not exceed 4°C;
  • When traveling in a country with poor sanitary conditions, prefer water, soft drinks, bottled beer, and, with a little more precaution, tea, and coffee prepared with boiled water. Avoid raw vegetables and unpeeled fruit;
  • get vaccinated against typhoid fever if you plan to travel to a typhoid fever country. Both typhoid fever and cholera are contracted through the ingestion of contaminated food or water.

Preventing gastroenteritis in young children

In children, rotavirus infections are virtually inevitable, especially if the child is kept in a community. Thus, by the age of 5, more than 95% of children will have been infected at least once by this virus.

However, since 2006 there has been a vaccine against rotavirus gastroenteritis to be given to babies from 6 weeks of age. Vaccination consists of 2 or 3 doses, administered orally, with an interval of at least 1 month between doses. Talk to a doctor.

Measures to prevent complications

It is advisable to rehydrate well in order to replace lost fluids.

Consult a doctor if there are any worrying signs.

Gastroenteritis is an infection of the digestive system that causes nausea, vomiting, diarrhea, etc. What medical treatments are available?

How to treat gastroenteritis?

Most people recover within 1 to 3 days. The purpose of the treatment is:

  • rehydrate;
  • prevent dehydration.

Isolation of the sick person is desirable. So it is better to stay at home and rest.


It is recommended, when there is vomiting, to wait a few hours after they have stopped before drinking or eating to allow the digestive system to recover. However, young children may try drinking a rehydration solution when they have gone 30 minutes without vomiting.

Then, drink small sips of water or a rehydration solution such as Gastrolyte® that can be found in pharmacies. You can also make it yourself, which is less recommended. Avoid consuming too much at once. At first, it is advisable to take about 1 tablespoon of solution every 10 minutes, then gradually increase.

If vomiting resumes:

  • wait 30 minutes;
  • Try to absorb some water or rehydration solution again.

It is also recommended to:

  • avoid alcohol, which dehydrates and irritates the digestive system;
  • Avoid drinking several glasses of sugary soft drinks a day, including cola. Their high sugar content can make diarrhea worse.

Rehydration solutions

Method of preparation: mix:

  • 360 ml of unsweetened orange juice;
  • 600 ml of cooled boiled water with the addition of 1/2 tsp table salt.

Storage: Solutions can be stored for 12 hours at room temperature and 24 hours in the refrigerator.

Beware of mistakes! An error, for example in the amount of salt, when preparing the solution can lead to serious complications. For this reason, most experts recommend using a commercial solution like Pedialyte or Gastrolyte, especially in children.


  • soft drinks such as 7-up even decarbonated;
  • sweetened or undiluted fruit drinks or juices.

Infant rehydration

It is advisable to offer the child frequently an electrolyte rehydration solution, on sale in pharmacies:

  • preferably fresh;
  • several times an hour;
  • in small sips or with a spoon.

Start with as little as 5 to 15 ml at a time.

The amount varies according to age:

  • from 0 to 6 months: 30 to 90 ml per hour is given;
  • from 6 months to 2 years: from 90 to 120 ml per hour;
  • For two years: from 125 to 250 ml per hour.

If the child starts vomiting again, we take a break of 30 to 60 minutes and start again from the beginning: 5-15 ml at a time.

What to eat in case of gastro? What foods to avoid?

As long as discomfort persists, it is best to avoid the following foods, which aggravate cramps and diarrhea:

  • dairy products;
  • citrus juices;
  • meat;
  • spicy dishes;
  • treats;
  • high-fat foods, including fried foods;
  • foods that contain wheat flour: bread, pasta, pizza, etc.;
  • corn and bran, which are rich in fiber;
  • fruits, with the exception of bananas, which would be rather beneficial, even in young children from 5 months to 12 months;
  • raw vegetables.

Once nausea is gone, gradually reintroduce a solid diet with certain foods that are easier to digest and reduce diarrhea such as:

  • starchy foods such as white rice;
  • sugar-free cereals;
  • white bread;
  • crackers.

It is advisable to stop eating if symptoms return. Then, it is possible to gradually add:

  • fruits and vegetables;
  • yogurt;
  • then protein foods: lean meat, fish, eggs, cheese, etc.


If necessary, taking paracetamol, via Acet®, Tylenol®, or Tempra®, can relieve stomach aches.

To “block” diarrhea, especially when traveling, antidiarrheal drugs, such as loperamide, for example, Imodium® or Diar-Ezee®, or diphenoxylate hydrochloride or Lomotil®, can be used. However, they do not treat the infection and should be avoided as much as possible. They are contraindicated in the presence of high fever or blood in the stool.


In more severe cases, hospitalization may be necessary. Doctors then use an intravenous infusion to rehydrate the body. Antibiotics are prescribed as needed to treat severe bacterial gastroenteritis.

The following complementary approaches may help relieve symptoms, in addition to rehydration. Some also speed up healing.

Effective complementary approaches for gastroenteritis


Probiotics are useful microorganisms for our intestinal flora. Their consumption can reduce the duration and intensity of gastroenteritis symptoms. Effective strains in acute gastroenteritis are:

  • lactobacilli, including Lactobacillus caseii GG and Lactobacillus reuteri;
  • yeast Saccharomyces boulardii.

In addition, probiotics may reduce the risk of contracting infectious diarrhea, due to rotavirus, E. coli, or Turista, in both children and adults, as shown by two systematic reviews and two meta-analyses of clinical trials. Their results demonstrate the usefulness of various strains of lactobacilli, including Lactobacillus GG: Lactobacillus rhamnosus or Lactobacillus casei of the rhamnosus subspecies.

Finally, the probiotics Saccharomyces boulardii and a mixture of Lactobacillus acidophilus and Bifidobacterium bifidum appear to be effective in protecting against traveler’s diarrhea, or turista. This was shown by a meta-analysis of 12 studies.

Psyllium or Plantago sp.

Psyllium may be helpful in reducing diarrhea. Indeed, as the mucilage it contains absorbs water in the intestine, it makes the stool more consistent. Since psyllium also slows down the emptying of the stomach and intestine, it allows the body to reabsorb more water.

Positive results have been obtained in people with diarrhea caused by taking certain medications or with fecal incontinence.


  • take 10 to 30 g per day of psyllium, in divided doses, with a full glass of water;
  • start with the smallest dose;
  • Increase until you get the desired effect.

It may be necessary to increase the dose to 40 g per day, or 4 doses of 10 g each.

Cautions: Regular psyllium intake may require adjustment of diabetes therapy. In addition, the consumption of psyllium would reduce the absorption of lithium.

Flax seeds or Linum usitatissimum

Commission E and ESCOP recognize the use of flaxseed to relieve short-term irritation and inflammation of the mucous membranes of the stomach and intestine. The mucilage of flaxseeds would form a protective layer on the intestinal mucosa.


  • Soak 5 to 10 g of crushed or ground seeds in 150 ml of warm water for 20 to 30 minutes;
  • filter;
  • drink the liquid.

Peppermint or Mentha piperita

ESCOP recognizes the use of peppermint leaves, orally, to relieve inflammation of the mucous membranes of the stomach and intestine. Traditionally, peppermint has been used for:

  • promote digestion;
  • relieve nausea;
  • Calm the pain.

Dosage: take 3 to 4 cups of infusion daily: infuse, for 10 minutes, 1 tablespoon of dried leaves in 150 ml of boiling water.

Chinese Pharmacopoeia

It seems that the preparation of Bao Ji Wan or Po Chai can help treat gastroenteritis. It would tone the digestive system and facilitate digestion. Use at the first sign of nausea and diarrhea.

The roots and leaves of isatis or Isatis tinctoria are also used in Chinese medicine to relieve gastroenteritis.

As for ginger, it is an antinauseant.

It is necessary to consult beforehand a practitioner trained in traditional Chinese medicine.

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