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Hydrating and rehydrating when you have gastroenteritis

When you have gastroenteritis, your body eliminates large quantities of water and mineral salts that are essential to your body’s proper functioning.

It is important to drink plenty of fluids and replenish mineral salts to prevent dehydration. Watch for signs of dehydration

To promote recovery, you must drink more fluids, such as water. You or your child can also use a rehydration solution. It is best to use commercial rehydration solutions. Homemade rehydration solutions are an alternative.

Commercial rehydration solutions

To rehydrate, it is best to use a commercial rehydration solution, such as Gastrolyte, Pedialyte or Pediatric Electrolyte. Commercial rehydration solutions contain the ideal proportion of water, sugar and mineral salts your body needs to recover. They allow the body to absorb fluids better so that you can keep yourself well hydrated. They also replace mineral salts lost due to diarrhea or vomiting.

These solutions are sold over the counter in pharmacies in a ready-to-drink liquid, freezies and in powder dissolved in water. The premixed forms are recommended. If you choose powders, be sure to mix them as directed to be safe.

Homemade rehydration solutions

If you cannot get a commercial rehydration solution, you can prepare a solution yourself. Mix the following ingredients:

  • 360 ml (12 oz) of unsweetened ready-to-drink orange juice
  • 600 ml (20 oz) of boiled water that has been chilled
  • 2.5 ml (1/2 tsp) of salt

You must use the exact quantities specified to avoid making your condition worse.

How much rehydration solution should you drink at home?

Adults who do not show signs of dehydration should take small, frequent sips of rehydration solution and increase the amount as tolerated in case of vomiting. An adult with diarrhea should drink between 100 and 240 ml of solution after each bowel movement.

Call Info-Santé 811 to find out how much solution you should drink and when you should drink it if you:

  • Are diabetic
  • Show signs of dehydration
  • Have a health problem that requires you to limit the amount of fluids you drink

A nurse will tell you exactly what you need to do based on your condition.

Also see the Foods to eat when you have gastroenteritis page to find out which food to eat when you have gastroenteritis.

Instructions for rehydrating children

Encourage your child to drink using a cup, bottle, spoon, dropper or syringe. Don’t prevent your child from drinking if he is thirsty and offer liquid every 5 to 15 minutes.

If your child is breastfed or bottle fed, he can continue drinking his usual milk (breast milk, commercial formula or whole milk (3.25% milk fat)). Breastfeed the baby as often as possible, for shorter periods of time, without measuring the amount.  If the baby is bottle fed, offer smaller quantities, more often.

Rehydration solutions must be offered to children over 12 months if:

  • there is significant or very frequent vomiting or diarrhea
  • they refuse or vomit the breast milk or infant formula

Amount to offer

To start, offer 5 ml (one teaspoon) to 15 ml (one tablespoon) of liquid. If tolerated, slowly and gradually increase up to the amount recommended for their age:

  • 0 to 6 months: 30 to 90 ml per hour (1 to 3 ounces)
  • 6 months to 2 years: 90 to 180 ml per hour (3 to 6 ounces)
  • older than 2 years: 180 to 250 ml per hour (6 to 8 ounces)

If your child wants to drink more, slowly increase the frequency and quantity until he can drink to quench his thirst. If your child has significant diarrhea and vomiting, offer a little more liquid to compensate for what was lost.

If your child starts vomiting again, give him a 30- to 60-minute break, then start the process over again.

After 4 hours of well-tolerated rehydration, gradually start eating again. For further information on eating when you have gastroenteritis, see Foods to eat when you have gastroenteritis.

Instructions for people at risk of complications

Children under 2 years old are at greater risk of dehydration. Rehydration must begin as soon as possible with gastroenteritis to avoid complications. When in doubt, call Info-Santé 811 for advice specific to your child’s situation.

If you are someone at risk of complications, call Info-Santé 811. A nurse will be able to give you advice on rehydration and eating specific to your situation.

Last update: December 2, 2022


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