What does ORS include? A Pharmacological Guide to Oral Rehydration Solutions

October 9, 2025 •

4 min read

Oral rehydration solution (ORS) is credited by the World Health Organization (WHO) and UNICEF with saving millions of lives annually. This simple yet powerful formulation is designed to efficiently counteract dehydration, so a critical question to understand its effectiveness is: What does ORS include?.

Quick Summary

An oral rehydration solution contains a precise blend of clean water, glucose, and key electrolytes such as sodium, potassium, and chloride. This medically balanced mix is designed to rapidly restore fluid and electrolyte levels lost from the body, most notably during bouts of diarrhea and vomiting.

Key Points

Core Ingredients: An oral rehydration solution (ORS) consists of clean water, glucose (sugar), and a specific balance of electrolytes, including sodium, potassium, and chloride.
Facilitated Absorption: The glucose in ORS is not for energy but to activate the sodium-glucose cotransport mechanism, which significantly enhances the small intestine's absorption of sodium and water.
WHO Standard: The World Health Organization (WHO) recommends a reduced-osmolarity formula with specific concentrations of salts and glucose to optimize fluid uptake and reduce diarrhea duration.
Not a Sports Drink: Unlike sports drinks, ORS has a much lower sugar content and a medically balanced ratio of electrolytes, making it a safer and more effective treatment for illness-related dehydration.
Precision is Key: For safety and efficacy, commercially prepared ORS is recommended over homemade versions, as incorrect measurements of salts and sugars can worsen a dehydrated state.

Core Ingredients of Oral Rehydration Solution

An oral rehydration solution (ORS) is a mixture of water, sugar (glucose), and specific salts (electrolytes) formulated to treat and prevent dehydration. The specific balance of these components is what makes it so effective, allowing for faster and more efficient rehydration than drinking plain water or sugary beverages.

Water: The Base of the Solution

Clean drinking water is the foundation of any ORS. It is the vehicle for delivering the other essential ingredients throughout the body. For powdered ORS, it is crucial to mix the powder with the specified volume of safe water to ensure the correct concentration is achieved. Using an incorrect amount of water can either dilute the solution, making it less effective, or concentrate it, potentially worsening dehydration.

Glucose: The Transport Agent

Glucose, a simple sugar, is a critical component of ORS, but not primarily for energy. Its main function is to facilitate the absorption of sodium and, consequently, water in the small intestine through a process called the sodium-glucose cotransport mechanism. This mechanism allows the body to absorb fluids and salts even during severe diarrhea, when normal absorption processes are impaired.

Electrolytes: The Essential Salts

Electrolytes are minerals vital for regulating fluid balance, nerve signals, and muscle function. An ORS contains several key electrolytes to replace those lost through vomiting, diarrhea, or excessive sweating.

Sodium: As sodium chloride (table salt), sodium is crucial for stimulating water absorption in the small intestine.
Potassium: As potassium chloride, this electrolyte helps regulate fluid balance and is often lost during diarrhea. Standard ORS contains more potassium than standard intravenous fluids to address these specific losses.
Chloride: Works alongside sodium and potassium to maintain the body's electrical charge and fluid balance.
Citrate or Bicarbonate: A base, such as trisodium citrate, is included to correct metabolic acidosis that can occur during severe dehydration.

The World Health Organization (WHO) Reduced-Osmolarity Formula

Since 2002, the WHO has recommended a reduced-osmolarity ORS formula, which is considered more effective than older versions. This formula has a lower overall concentration of solute particles, which facilitates better fluid absorption and reduces stool volume. The standard WHO reduced-osmolarity formula includes per liter of water:

Glucose (anhydrous): 13.5 g (75 mmol/L)
Sodium chloride (NaCl): 2.6 g (75 mmol/L)
Potassium chloride (KCl): 1.5 g (20 mmol/L)
Trisodium citrate (dihydrate): 2.9 g (10 mmol/L)

This yields a solution with a total osmolarity of 245 mOsm/L, optimizing fluid intake.

ORS vs. Sports Drinks: A Critical Comparison

Many people mistakenly believe sports drinks are a suitable substitute for an oral rehydration solution. While both contain water, sugar, and electrolytes, their formulations are designed for different purposes and contain significantly different ratios of key ingredients.


Feature	Oral Rehydration Solution (ORS)	Sports Drink (e.g., Gatorade)
Primary Purpose	To treat mild to moderate dehydration caused by illness (diarrhea, vomiting).	To replenish fluids, electrolytes, and muscle glycogen lost during strenuous exercise.
Sugar Content	Lower sugar content, formulated to maximize fluid absorption via the sodium-glucose cotransport mechanism.	Higher sugar content, designed to provide energy for athletic performance. Excess sugar can worsen diarrhea.
Electrolyte Balance	Medically formulated with a specific, precise balance of sodium, potassium, and other salts.	Contains electrolytes, but often in a lower concentration and different ratio than ORS.
Safety for Illness	Highly effective and recommended by health organizations like the WHO and CDC for treating dehydration from illness.	Can be less effective for illness-related dehydration due to high sugar and low electrolyte levels. Some can even worsen diarrhea.

Homemade ORS: A Risky Alternative

While some recipes for homemade ORS exist, health experts generally advise against them. The precise balance of ingredients in a commercial ORS is crucial for efficacy and safety. An improperly mixed solution can be dangerous:

Too much glucose (sugar): Can draw water into the intestine, worsening diarrhea.
Too much or too little sodium: Can cause a dangerous electrolyte imbalance, leading to hypernatremia (salt toxicity) or exacerbating hyponatremia.

Commercial ORS packets offer a safe, reliable, and convenient option for treating dehydration.

Proper Administration and Who Benefits from ORS

ORS is not a substitute for regular fluid intake. It is specifically indicated for rehydrating individuals experiencing fluid loss due to diarrhea, vomiting, or excessive sweating.

Children: Infants and young children are especially susceptible to dehydration from diarrhea and are a key target for ORS treatment.
Travelers: Can be used to prevent and treat travelers' diarrhea, particularly in areas with poor water quality.
Athletes: Used for recovery after intense exercise, especially in hot climates.
Individuals with certain medical conditions: Patients with chronic conditions, such as those with short bowel syndrome, may benefit from ORS to manage electrolyte imbalances.

Note: ORS is for mild to moderate dehydration. Severe dehydration is a medical emergency requiring intravenous fluids. Always consult a healthcare provider for persistent or severe symptoms.

Conclusion

In conclusion, an oral rehydration solution (ORS) is a scientifically formulated medical product containing clean water, glucose, and key electrolytes such as sodium, potassium, and chloride. Its precise composition leverages the sodium-glucose cotransport mechanism to maximize fluid and electrolyte absorption, making it far more effective than plain water or sports drinks for treating dehydration from illness. The WHO's reduced-osmolarity formula represents the current best practice, and for safety, commercially prepared packets are recommended over homemade recipes. Understanding what does ORS include is vital for appreciating its lifesaving efficacy in combating dehydration globally.

Frequently Asked Questions

The primary function of glucose in an ORS is to act as a transport agent. It works with sodium to help the body absorb water more efficiently through the sodium-glucose cotransport mechanism in the small intestine.

ORS is better because it contains a balance of electrolytes and glucose that plain water lacks. The combination of sodium and glucose enhances water absorption, effectively replacing the fluids and salts lost during a bout of diarrhea.

The key difference is their formulation and purpose. ORS has a specific, medically balanced ratio of electrolytes and a lower sugar concentration optimized for treating dehydration from illness, while sports drinks often have high sugar content intended for athletic performance, which can worsen diarrhea.

While some homemade recipes exist, health experts generally recommend against them. The precise balance of ingredients is critical for proper function, and an incorrect mixture can be ineffective or even dangerous. Commercial ORS packets are a safer and more reliable option.

ORS is used to treat and prevent mild to moderate dehydration caused by diarrhea, vomiting, excessive sweating from fever or exercise, and other conditions that lead to significant fluid and electrolyte loss.

Individuals with severe dehydration, altered mental status, or specific medical conditions like kidney disorders or heart failure should use ORS with caution and under medical supervision. Severe dehydration requires immediate intravenous (IV) treatment.

The common electrolytes in an ORS include sodium (as sodium chloride), potassium (as potassium chloride), chloride, and a base like citrate (as trisodium citrate).