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Oral rehydration solution (ORS)

Written by Stephanie Nera, RPh, PharmD · Pharmacology

Updated Sep 20, 2023


Oral rehydration salts are used to treat dehydration caused by diarrhea, fluid loss, burns, and other conditions that cause water and electrolyte deficiency.

Oral rehydration salts do not treat the cause of diarrhea, but rather replace the lost salts, sugars, and water. If the cause of dehydration is due to an infection, additional antimicrobial and vitamin (zinc) supplementation may be necessary.

How should I take oral rehydration salts (ORS)?

For the oral powder, open the sachet and pour the contents into 200 mL of distilled or purified (not mineral) drinking water. Stir well until all the powder has dissolved and the solution is clear or slightly cloudy.

Make sure your child drinks the entire glass of solution. If they cannot drink it all in one go, they can drink it over about 30 minutes. It may help to use a straw.

Oral rehydration salts are usually given after each runny stool (diarrhea).

Your doctor will calculate the exact dose of oral rehydration salts that is right for your child. If you bought it over-the-counter, the estimated doses will be shown on the product label or box. Encourage your child to drink as much as they can of the recommended dose.

How do I store oral rehydration salts (ORS)?

This drug should be stored at room temperature (<30°C) and be protected from moisture. Always check the label before using this product. For safety, keep out of the reach of children and pets.

After mixing the solution, do not keep the solution for more than one hour at room temperature. It can safely be stored in the refrigerator (2-8°C) for up to 24 hours.

Do not use if the printed expiration date has passed, the product seal has been broken, or the product has changed in color, odor, or consistency.

Do not dispose of this product by pouring it down the drain, toilet, or into the environment. Ask your pharmacist regarding the proper way and location of disposal.

Precautions & Warnings

What should I know before using oral rehydration salts (ORS)?

Before using this drug, tell your doctor if:

  • You are pregnant or breastfeeding
  • You are taking any other medicines or supplements
  • You have a history of allergy to this product or any food, medication, or other substances.
  • You have any underlying health conditions

Is it safe during pregnancy or breastfeeding?

ORS and other electrolytes are considered safe for use in pregnant and lactating women when there is a risk of dehydration.

Consult with your doctor regarding your hydration status, as ORS may not be enough in moderate-to-severe cases of dehydration. Dehydration can affect pregnant and lactating women more severely than other populations of patients.

Side Effects

When prepared and taken as recommended, no side effects are expected to occur. While side effects are not likely to happen even with additional doses, excessive amounts or megadoses of salt, sugar, or water can cause adverse effects.

Potential adverse effects include:

  • Overhydration or water intoxication
  • Worsening of diarrhea
  • Water retention
  • Edema or swelling
  • Increased blood sugar

These side effects are more likely to occur if the solution is made at home rather than using the premade ORS sachets or when the solution is diluted or followed with too much water.

You or your child may experience some, none, or other side effects not mentioned above. If you have any concerns about a side effect or it becomes bothersome, consult your doctor or pharmacist.


Oral rehydration salts may interact with other drugs that you are currently taking, which can change how your drug works or increase your risk for serious side effects.

To avoid any potential drug interactions, you should keep a list of all the drugs you are using (including prescription drugs, nonprescription drugs, and herbal products) and share it with your doctor and pharmacist.

If you experience an adverse drug interaction, do not start, stop, or change the dosage of any drugs without your doctor’s approval. Inform your doctor immediately to reevaluate your treatment plan. Your dose may need to be adjusted, substituted with another drug, or discontinue using the drug.

Does food or alcohol interact with oral rehydration salts (ORS)?

There are no significant food or alcohol interactions with ORS. Avoid alcohol intake to prevent worsening dehydration.

Inform your doctor or pharmacist if you have any concerns regarding food-drug interactions.

What health conditions may interact with oral rehydration salts (ORS)?

Oral rehydration salts may interact with your health condition. This interaction may worsen your health condition or alter the way the drug works. It is important to always let your doctor and pharmacist know all the health conditions you currently have.

This drug should be taken with caution if you have any of the following conditions or risk factors:

  • Pre-existing blood disorders
  • Gout
  • Dental disease
  • Liver disease
  • Heart disease
  • Gastrointestinal obstruction
  • Kidney impairment


The information provided is not a substitute for any medical advice. You should ALWAYS consult your doctor or pharmacist before using oral rehydration salts (ORS).

What is the dose of oral rehydration salts (ORS) for an adult?

The recommended dose is 200 to 400 mL in 24 hours.

What is the dose of oral rehydration salts (ORS) for a child?

According to the WHO, fluid replacement doses are based on the age and current hydration status of the child.

For no dehydration (with episodes of loose stools)

  • Ages <2 years: Give 50 to 100 mL after each loose stool, up to 500 mL/day.
  • Ages 2-9 years: Give 100 to 200 mL after each loose stool, up to 1 L/day.
  • Ages 10 years and above: Give as much as tolerated, up to 2L/day.

For some dehydration (administer within the first 4 hours)

  • Ages <4 months or <5 kg: Give 200 to 400 mL
  • Ages 4 to 11 months or 5 to 7.9 kg: Give 400 to 600 mL
  • Ages 1 to 2 years or 8 to 10.9 kg: Give  600 to 800 mL
  • Ages 2 to 4 years or 11 to 15.9 kg: Give 800 to 1200 mL
  • Ages 5 to 14 years or 16 to 29.9 kg: Give 1200 to 2200 mL
  • Ages 15 years and above or 30 kg or more: Give 2200 to 4000 mL

For severe dehydration

Give intravenous (IV) Ringer’s Lactate or, if not available, normal saline and ORS as outlined above. Do not give plain glucose or dextrose solution.

In cases of severe dehydration, seek emergency medical assistance as soon as possible. Give rehydration solutions at home until you can make it to the hospital.

How is oral rehydration salts (ORS) available?

Oral rehydration salts are available in the following dosage forms and strengths:

  • Oral powder in sachet (ratio and concentration of ingredients varies depending on the brand)

What should I do in case of an emergency or overdose?

In case of an emergency or an overdose, call your local emergency services or go to your nearest emergency room.

What should I do if I miss a dose?

If you miss a dose of oral rehydration salts, take it as soon as possible. However, if it is almost time for your next dose, skip the missed dose and take your regular dose as scheduled. Do not take a double dose.


Hello Health Group does not provide medical advice, diagnosis or treatment.

Written by

Stephanie Nera, RPh, PharmD


Updated Sep 20, 2023

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