How Drinking Water Mixed with Salt and Sugar Helps During Diarrhea

November 16, 2025 •

3 min read

According to the World Health Organization (WHO), oral rehydration solution (ORS) has saved millions of lives globally by treating dehydration caused by diarrheal diseases. Drinking water mixed with salt and sugar is a fundamental component of this life-saving therapy, working through a scientifically proven mechanism to restore the body's fluid balance.

Quick Summary

This guide explains the physiological mechanism of why a specific mixture of salt and sugar in water is essential for treating diarrhea-related dehydration. It details how this solution, known as oral rehydration solution, utilizes glucose-sodium co-transport to enhance water and electrolyte absorption in the intestines. The text covers the correct preparation, effectiveness compared to plain water, and crucial safety precautions.

Key Points

Sodium-Glucose Mechanism: The mixture works by leveraging the sodium-glucose co-transport system, where glucose in the solution helps the intestines absorb sodium and water more effectively.
Restores Electrolytes: Diarrhea causes a dangerous loss of essential electrolytes like sodium and potassium; ORS replaces these vital minerals, which plain water cannot do.
Prevents Dehydration: The solution replenishes lost fluids rapidly, preventing severe dehydration, organ damage, and other serious complications associated with diarrhea.
Requires Specific Ratios: For a homemade ORS to be effective and safe, the precise WHO-recommended ratio of salt and sugar to water must be followed carefully.
Acts as First Response: ORS is a critical first-line treatment for mild to moderate dehydration, reducing the need for more invasive intravenous fluid therapy.
Not a Cure for All: While effective for rehydration, ORS does not stop diarrhea itself. Its purpose is to correct fluid imbalances while the body fights the underlying cause.
Safe for Children: ORS is a safe and highly recommended therapy for managing diarrhea-related dehydration in children, who are particularly vulnerable to fluid loss.

The Science of Oral Rehydration Solution (ORS)

Diarrhea causes the body to lose a significant amount of water and essential electrolytes, such as sodium, chloride, and potassium. This rapid loss, if unaddressed, can lead to dangerous dehydration, especially in children and the elderly. The simple combination of water, salt, and sugar is a treatment known as Oral Rehydration Solution (ORS), which is absorbed efficiently by the small intestine even during a diarrheal episode.

The Sodium-Glucose Co-Transport Mechanism

The effectiveness of ORS hinges on a powerful physiological process called sodium-glucose co-transport. In the small intestine, specific carrier proteins called sodium-glucose cotransporters (SGLTs) transport glucose into the intestinal cells. This transport is dependent on the presence of sodium. When glucose is actively absorbed, it creates an osmotic gradient that pulls sodium and, crucially, water from the intestine into the bloodstream. This mechanism continues to function even when diarrhea-causing infections have disrupted other intestinal processes.

Glucose: The sugar in the solution is not merely for energy or taste. Its primary function is to act as a transport partner for sodium. Without glucose, sodium is poorly absorbed, and water absorption is inefficient.
Sodium (Salt): This key electrolyte is lost in large amounts during diarrhea. The sodium in the ORS is essential for the glucose co-transport pump to operate, allowing the body to take in both water and vital electrolytes.
Water: The clean water is the solvent that carries the salts and sugar, replenishing the volume of fluids lost through loose stools.

Proper Preparation of Homemade ORS

For moderate dehydration, it is recommended to use a pre-packaged ORS from a pharmacy, as these contain the precise, World Health Organization (WHO) recommended ratios of ingredients. However, in resource-limited or emergency situations, a homemade version can be a life-saving alternative.

To prepare a basic solution:

Wash your hands thoroughly with soap and clean water.
Boil one liter of clean water and let it cool completely.
Measure six level teaspoons of sugar and half a level teaspoon of salt.
Mix until both the sugar and salt are completely dissolved.
Administer to the patient in frequent sips. Discard any unused solution after 24 hours.

The Difference: ORS vs. Plain Water

While plain water is always better than no fluid, it is not an ideal replacement for severe fluid and electrolyte loss during diarrhea. Here is a comparison:


Feature	Plain Water	Oral Rehydration Solution (ORS)
Mechanism	Replenishes water passively. Limited electrolyte and water absorption in the small intestine during diarrhea.	Actively transports water and sodium into the bloodstream using the sodium-glucose co-transport pump, even during diarrhea.
Effectiveness	Not fully effective for replenishing lost electrolytes and fluids in moderate to severe dehydration.	Highly effective for treating and preventing dehydration associated with diarrhea.
Electrolyte Replacement	Contains no or minimal electrolytes. Does not replace the sodium, potassium, and chloride lost through liquid stools.	Contains a balanced mixture of essential electrolytes, addressing the chemical imbalance caused by diarrhea.
Safety in Dehydration	Can worsen electrolyte imbalance, especially hyponatremia (low sodium), if consumed in large quantities without replacing salts.	Safe and specifically formulated for rehydration, restoring the correct balance of fluids and salts.

When to Seek Medical Attention

Though an oral rehydration solution is highly effective for mild to moderate dehydration, severe cases require immediate professional medical care. Seek medical help if you experience symptoms of severe dehydration, such as lethargy, dizziness, inability to drink, decreased urination, or if the diarrhea persists for more than 48 hours. For infants and young children, consult a doctor if diarrhea does not improve within 24 hours.

Conclusion

The science behind drinking water mixed with salt and sugar during diarrhea is not a folk remedy but a foundation of modern medicine. By leveraging the body's natural sodium-glucose co-transport system, this simple mixture, correctly prepared, can rapidly restore the critical balance of fluids and electrolytes lost. Whether through a commercial product or a homemade solution, oral rehydration therapy remains an affordable, accessible, and essential tool for combating the life-threatening effects of dehydration from diarrheal disease. It is a testament to the power of a simple, scientifically sound approach to health care. For additional information on specific oral rehydration salts formulations and diarrhea management, consult the guidelines published by the World Health Organization (WHO), such as the Guideline for Cholera Prevention and Control.

Frequently Asked Questions

According to the World Health Organization's basic recipe, you should mix half a level teaspoon of salt and six level teaspoons of sugar into one liter of clean, boiled, and cooled water. This creates a solution that is effective for rehydration.

The sugar (glucose) is necessary because it facilitates the absorption of sodium and, by extension, water in the small intestine through a process called sodium-glucose co-transport. Without the glucose, the intestinal absorption of salt and water is much less efficient.

Plain water replaces fluid but does not replace the crucial electrolytes lost with diarrhea. ORS contains both water and a balanced mix of electrolytes (salts) and sugar, which work together to maximize rehydration and restore the body's electrolyte balance.

No, most sports drinks are not ideal substitutes for ORS. They often contain too much sugar and too little sodium, which can draw water into the intestines and worsen diarrhea. They should only be used if no better alternative is available.

If a child is vomiting, wait 5-10 minutes and then resume giving the ORS solution in very small, frequent sips. Using a spoon or syringe to give small amounts every minute or two can help minimize vomiting. Continue breastfeeding infants.

Seek medical attention if symptoms of severe dehydration appear, including extreme thirst, dizziness, lethargy, decreased urination, or if diarrhea persists for more than 48 hours. Infants and young children with persistent diarrhea also warrant a doctor's visit.

It is generally not recommended to add flavorings to a homemade ORS, as many added juices or sodas contain high amounts of sugar that can worsen diarrhea. For infants, continuing regular breastfeeding is best. If a commercial ORS is needed, some may come in flavored varieties.