Oral rehydration salts, often abbreviated as ORS, are a specially formulated combination of glucose and electrolytes used to replace fluids and salts lost during diarrhea, vomiting, and other conditions associated with dehydration [1]. Their main value is that they do more than replace water - they help the body absorb and retain fluids more efficiently [1], [2].
ORS are not simply a drink with “a little salt and sugar.” Their composition is carefully designed to support sodium and water absorption in the intestines, which is especially important in viral gastroenteritis, traveler's diarrhea, food poisoning, or frequent vomiting [2], [3].
Standard oral rehydration salts contain several basic components: glucose, sodium chloride, potassium chloride, and sodium citrate [1]. When the powder is dissolved in the exact amount of water specified, it forms a solution intended to replace fluids and electrolytes [1].
Glucose is not included only for energy. Its main role is to help sodium absorption in the small intestine. When sodium and glucose are absorbed together, water follows that process, making rehydration more efficient than drinking plain water alone [2], [3].
Sodium is essential for maintaining fluid balance and blood pressure, potassium is important for muscle and heart function, and citrate helps correct metabolic disturbances that can occur during diarrhea [1], [2].
With diarrhea and vomiting, the body loses both water and electrolytes. Plain water can reduce thirst, but it does not replace lost sodium and potassium in appropriate amounts [2]. Juices and soft drinks often contain too much sugar, which can worsen diarrhea in some people by increasing the osmotic load in the intestines [3], [4].
Sports drinks are designed primarily to replace fluids and electrolytes during physical activity, but they usually do not have the same balance of sodium, glucose, and overall osmolarity as oral rehydration solutions intended for diarrhea and vomiting [2], [3].
That is why ORS have an advantage when there is a real risk of dehydration due to diarrhea, vomiting, or gastroenteritis [2], [4].
Oral rehydration salts are most commonly used for acute diarrhea, vomiting, viral gastroenteritis, traveler's diarrhea, and mild to moderate dehydration [3], [4]. They are especially useful when a person has several watery stools per day, is vomiting, feels very thirsty, has a dry mouth, weakness, darker urine, or urinates less often than usual [3], [4].
In children, ORS are often recommended as first-line rehydration for gastroenteritis, particularly when there is an increased risk of dehydration [4]. In adults, they can be used in similar situations, especially when fluid losses are rapid or the person is unable to eat and drink normally [2], [3].
ORS are most useful when started early, before dehydration becomes pronounced [3].
ORS powder should be dissolved in exactly the amount of water stated on the sachet or in the manufacturer's instructions. This is very important because too much water can dilute the solution, while too little water can make it too concentrated and unsuitable for the body [1].
Do not add sugar, salt, juice, milk, or other beverages to prepared ORS because this changes the balance of ingredients and may reduce the effectiveness or safety of the solution [1], [3].
If a person is vomiting, the solution should not be consumed all at once. It is better to take small sips frequently - for example, a few milliliters every few minutes. Even when vomiting is present, many people can be rehydrated successfully if ORS is given slowly and gradually [3].
The amount depends on age, body weight, degree of dehydration, and the amount of fluid being lost through stool or vomiting. In children, guidelines often use weight-based estimates, and in children at increased risk of recurrent dehydration, additional ORS after each larger watery stool may be considered [4].
In adults, ORS is taken according to thirst and ongoing losses, using small and frequent sips if nausea is present. Fluid intake should continue even after symptoms begin to improve because losses can continue for some time [2], [3].
For infants, young children, older adults, and people with chronic illnesses, it is better not to improvise the amount, but to follow the product instructions or seek advice from a doctor, pharmacist, or pediatrician [4], [5].
ORS are intended for mild to moderate dehydration, but they are not a substitute for urgent medical care when signs of severe dehydration are present. Medical attention is needed if a person cannot keep fluids down, vomiting persists, blood appears in the stool, there is marked drowsiness, confusion, dizziness on standing, a rapid pulse, very little urination, or signs of exhaustion [3], [5].
In children, warning signs include dry mouth, crying without tears, sunken eyes, marked drowsiness, cold hands and feet, fewer wet diapers, or refusal to drink [4], [5].
If severe dehydration is present, intravenous fluids and medical supervision may be required [3], [5].
Extra caution is needed in infants, young children, pregnant women, older adults, and people with kidney disease, heart disease, diabetes, electrolyte disorders, or weakened immunity [4], [5]. In these groups, dehydration can progress more quickly or have more serious consequences.
People who have sodium restrictions or severe kidney or heart disease should not use ORS without advice from a healthcare professional, especially if they plan to drink larger amounts of the solution [5].
Oral rehydration salts are one of the most important and practical ways to replace fluids and electrolytes during diarrhea and vomiting. Their advantage lies in the precise balance of glucose and electrolytes, which helps improve water absorption in the intestines [1], [2].
ORS are most commonly used for viral gastroenteritis, acute diarrhea, vomiting, and mild to moderate dehydration [3], [4]. They should be prepared exactly according to the instructions and taken gradually, especially when nausea is present.
If signs of severe dehydration, blood in the stool, persistent vomiting, or worsening general condition appear, ORS are not enough and medical care should be sought [3], [5].
[1] World Health Organization (WHO). Oral Rehydration Salts: Production of the New ORS. 2006.
https://www.who.int/publications/i/item/WHO-FCH-CAH-06.1
[2] Centers for Disease Control and Prevention (CDC). Managing Acute Gastroenteritis Among Children: Oral Rehydration, Maintenance, and Nutritional Therapy. 2003.
https://www.cdc.gov/mmwr/preview/mmwrhtml/rr5216a1.htm
[3] National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). Treatment of Diarrhea. Accessed 2026.
https://www.niddk.nih.gov/health-information/digestive-diseases/diarrhea/treatment
[4] National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). Treatment of Viral Gastroenteritis (“Stomach Flu”). Accessed 2026.
https://www.niddk.nih.gov/health-information/digestive-diseases/viral-gastroenteritis/treatment
[5] World Health Organization (WHO). Diarrhoeal Disease. Accessed 2026.
https://www.who.int/news-room/fact-sheets/detail/diarrhoeal-disease
Health Disclaimer: This content is for educational and informational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare professional before starting or changing any supplement, especially if you are pregnant, breastfeeding, have a medical condition, or take medication.
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