Gastroenteritis

Gastroenteritis

Does your child have gastroenteritis (a.k.a. stomach flu)? Be careful about dehydration—especially if your child is very young.


Symptoms

  • Diarrhea (more frequent and looser stools than usual)
  • Nausea or vomiting
  • Reduced appetite
  • Fever and stomach ache (sometimes)
  • Signs of dehydration (sometimes)

Seek medical attention immediately or go to the emergency room if your child:

  • Is under 3 months old
  • Vomits more than 6 or 7 times a day
  • Refuses to drink or throws up immediately after drinking
  • Has a dry tongue
  • Seems to be urinating less
  • Has stools with traces of blood
  • Has a hard, tender belly or bouts of severe abdominal pain

Consult a doctor if your child has persistent diarrhea (more than six bowel movements a day) lasting more than 5 days.

If in doubt, don’t hesitate to call Info-Santé 811.

What is gastroenteritis?

Gastroenteritis (also known as stomach flu) is an inflammation of the digestive system usually caused by a virus.

Its main complication is dehydration. This can develop quickly, especially in children under 2.

Signs of dehydration

Dehydration is the loss of fluids (made up of water and minerals) that are essential for the body to function properly.

Signs of mild dehydration

  • Decreased urine, saliva, and tears when crying
  • Darker urine
  • Dry skin, mouth, and tongue

Signs of severe dehydration

  • Significant decrease in urine (no urine for more than 6 to 8 hours for an infant, or more than 8 to 10 hours for a child aged 2 or older)
  • Dark, sunken eyes
  • Drowsiness or disorientation
  • Fever
  • General weakness
  • Sunken fontanelle (soft spot) on an infant

If your child shows signs of severe dehydration, take them to the emergency room.

Age: Gastroenteritis can affect anyone, but it’s most common in babies and children aged 5 and under.
Duration: In general, 3 to 5 days; but it often takes one week for stools to return to normal.
Infectious period: Viral gastroenteritis is highly contagious as long as a child is showing symptoms. Children may be contagious for a longer period if they have a weakened immune system due to another health issue.
How it spreads: Direct contact (vomit or feces) or indirect contact (contaminated surfaces and objects: towels, washcloths, bath gloves, toilets, glasses and utensils, toys, etc.).
Isolation period: If any of the following apply, it’s a good idea to keep your child at home: they are unable to participate in activities at daycare or school; they have a fever or vomited two or more times in the last 24 hours; their stool contains mucus or blood; their stool is overflowing from their diaper; they aren’t able to use the toilet for all their bowel movements.
The child can return to daycare or school even if their stool is still frequent and somewhat loose. Once they do, handwashing is very important to reduce the likelihood of transmission. Your child should have their energy back and be able to stay hydrated before they resume their normal activities.

Treatment

Anti-nausea, anti-vomiting, and anti-diarrheal medications are not recommended to treat gastroenteritis. Some of these medications may even make the illness worse and cause significant side effects in children.

Antibiotics are also ineffective for viral gastroenteritis. In some cases, the doctor may order a stool test to determine the nature of the infection. If it is caused by a bacterium or parasite rather than a virus, the doctor will likely prescribe an antibiotic or antiparasitic.

The doctor’s main concern when treating gastroenteritis is making sure the child does not become dehydrated. If your child is severely dehydrated, they should be seen by a doctor as soon as possible.

In cases of severe or prolonged gastroenteritis, a child may develop a temporary lactase deficiency. The doctor may recommend switching to lactose-free milk.

Gastroenteritis vs. food poisoning

There’s no way to distinguish between viral gastroenteritis and food poisoning based on symptoms alone. Viral gastroenteritis is contagious

Texte source à vérifier, l’intoxication alimentaire n’est pas contagieuse. Merci!

, however, so you could check whether your child has been around other people who are also sick. Both conditions require the same care.

How to prevent dehydration

If your child is vomiting or has diarrhea, it’s important to make sure they drink enough fluids to prevent dehydration.

If your child is vomiting

Have them drink an electrolyte solution (e.g., Pedialyte®, Gastrolyte®) for 24 to 48 hours. These products are also available as freezer pops.

Don’t give your child “sports drinks” like Gatorade®. They don’t contain the right balance of water, sugar, and salt, and can make your child’s symptoms worse. Soft drinks (even if flat), fruit juices, and broths should all be avoided for the same reason.

If your baby refuses to drink a rehydration solution from a bottle, try giving it with a dropper, syringe, small spoon, or cup.

If your baby is breastfeeding, breastfeed more often but for shorter periods. You can also alternate between breastfeeding and bottle-feeding with an electrolyte solution. This can help them rehydrate more quickly, especially if they aren’t tolerating breast milk.

If your baby is only bottle-feeding, continue with their usual formula, but feed more often and in smaller amounts. Alternate the usual formula with bottles of electrolyte solution. Do not water down the formula.

To avoid causing more nausea and vomiting, give your child small amounts of liquid at very short intervals. The recommended quantities vary by age:

  • Under 6 months: 30 to 90 ml (1 to 3 oz.) per hour, or about 5 ml (1 tsp) every 5 minutes. Gradually increase this amount and lengthen the intervals between feeds according to your baby’s tolerance.
  • 6 months to 2 years: 90 to 125 ml (3 to 4 oz.) per hour, or about 10 ml (2 tsp) every 5 minutes. Gradually increase this quantity by lengthening the intervals according to your child’s tolerance.
  • Over 2 years old: 125 to 250 ml (4 to 8 oz.) per hour, or about 15 ml (1 tbsp) every 5 minutes. Gradually increase this quantity by lengthening the intervals according to your child’s tolerance.

Electrolyte solutions sold in pharmacies

Electrolyte solutions (e.g., Pedialyte® and Gastrolyte®) can help prevent dehydration and ensure your child gets essential minerals (electrolytes). Once opened, these solutions should be stored in the fridge and used within 48 hours. Powder packs and frozen solutions last longer. Be sure to check the expiry dates.
If you don’t have an electrolyte solution on hand, you can make a homemade rehydration solution. Be sure to follow the exact proportions:
  • 360 ml (12 oz.) pure orange juice (no sugar added)
  • 600 ml (20 oz.) cooled boiled water
  • 2.5 ml (1/2 tsp) salt

Feeding a child who is vomiting or has vomited

If your child is no longer vomiting or is vomiting very little (with or without diarrhea), or if they only have diarrhea:

  • If your baby is only breastfeeding or bottle-feeding, return to their usual feeding schedule.
  • If your child is older, resume their normal diet gradually as their vomiting subsides. Eating helps the intestines heal, so your child should start eating again as soon as possible. If they don’t eat, the diarrhea may persist longer, and they won’t be getting adequate calories, nutrients, minerals, or vitamins. For the same reasons, if your child has diarrhea without vomiting, they should stick to their usual diet as much as possible.
  • Give your child small amounts of food several times a day (5 or 6 small meals) to start.
  • Serve them whatever they feel like eating, including dairy products.
  • Avoid fatty or sugary foods (chips, fries, pastries, cold cuts, ice cream, juice, sodas, sugary cereals, dried fruit, fruit in syrup, candy, chocolate, etc.). Store-bought broths and soups (in packets or cans) should also be avoided since they are too salty.

Probiotics

To help relieve diarrhea and restore the balance of intestinal flora, it may be a good idea to give your child a probiotic such as Bio-K® or Lactibiane®. Foods naturally rich in probiotics, such as unsweetened yogurt with bacterial culture, kefir, and fermented vegetables like sauerkraut, can also help.

Prevention

The vaccine that protects against rotavirus gastroenteritis, the most common form of gastroenteritis in infants, is now part of the vaccination schedule. Two doses are needed to ensure your child is well protected: the first at 2 months and the second at 4 months. The vaccine comes in liquid form and is administered orally.

Children can still get gastroenteritis even if they’ve been vaccinated. This is because the vaccine protects only against rotavirus, and other viruses can also cause the illness.

Limiting the spread

Gastroenteritis is highly contagious. It spreads quickly among young children, as they are often in groups at daycare and wear diapers.

Here are some ways to limit the spread of the virus:

  • Clean and disinfect objects and areas that have been in contact with your child’s vomit or feces, including the toilet.
  • Make sure your child washes their hands thoroughly and frequently, especially after using the toilet and before eating. If they are too young to do this on their own, do it for them.
  • Make sure that everyone who comes into contact with your child also washes their hands. Wash your hands after taking them to the toilet or changing their diaper, before feeding them or giving them medicine, etc.
  • As much as possible, avoid direct contact between your baby and any older children who have diarrhea along with signs of a respiratory infection. This is even more important for infants under 3 months old. The gastroenteritis virus can also spread through respiratory droplets.

Preventing bacterial gastroenteritis

Most cases of gastroenteritis are caused by viruses, but your child may develop bacterial gastroenteritis—caused by bacteria like salmonella—after consuming contaminated food or water, or through contact with a person or animal whose feces contain bacteria.

To reduce the risk of bacterial gastroenteritis:

  • Avoid drinking water from streams or springs unless you’re sure it’s safe.
  • Follow basic hygiene rules in the kitchen:
       – Before preparing fruits and vegetables, peel them or rinse them under running water, especially if they will be eaten raw.
       – Disinfect surfaces that have come into contact with raw meat or fish.
       – Make sure meat is thoroughly cooked before eating.
  • Keep pet bowls and litter boxes away from areas where food is prepared or eaten. Reptiles, turtles, and lizards can carry bacteria that cause diarrhea.
  • When travelling to tropical countries, drink only bottled water. Peel fruit yourself and avoid foods that may have been washed in tap water. Avoid food sold at street stalls.
Naître et grandir

Scientific review: Dr. Isabelle Viel-Thériault, pediatrician and infectiologist at CHU de Québec
Research and copywriting:The Naître et grandir team
Updated: April 2025

Photo: Adobe Stock/ulza

Sources and references

Note: The links to other websites are not updated regularly, and some URLs may have changed since publication. If a link is no longer active, please use search engines to find the relevant information.

  • Billeau, Audrey. La Maman infirmière à la rescousse : tous les bobos et les soins des enfants de 0 à 6 ans. Montreal, Les Éditions de l’Homme, 2025, 232 pp.
  • Doré, Nicole, and Danielle Le Hénaff. From Tiny Tot to Toddler: A practical guide for parents from pregnancy to age two. Quebec City, Institut national de santé publique du Québec. inspq.qc.ca
  • Gouvernement du Québec. “Gastroenteritis (stomach flu).” 2023. quebec.ca
  • Gouvernement du Québec. “Rotavirus vaccine.” 2019. quebec.ca
  • KidsHealth. “Gastroenteritis (Stomach Flu).” 2021. kidshealth.org
  • Ministère de la Famille du Québec. Les infections en milieu de garde. 2019. cdn-contenu.quebec.ca
  • Canadian Paediatric Society. “Dehydration and diarrhea in children: Prevention and treatment.” Caring for Kids. 2018. caringforkids.cps.ca
  • Canadian Paediatric Society. “Food safety at home.” 2020. caringforkids.cps.ca

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