Oral Rehydration Salts
Also known as: ORS, oral rehydration solution, oral rehydration therapy
Randomized trials in healthy adults show ORS reduces urine output and increases short-term fluid retention compared with plain water, and promotes greater post-exercise rehydration than water; systematic reviews of treatments for acute diarrhoea list ORS among studied interventions. Evidence supports ORS for short-term replacement of fluid and electrolytes in these contexts.
Last reviewed: 2026-10-14 · 5 indexed studies
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Overview
Oral rehydration salts (ORS) are electrolyte–carbohydrate solutions formulated to restore plasma volume and replace losses of water, sodium and other electrolytes. They are used for rehydration after diarrhoea and for fluid replacement after exertional losses.
Mechanism & Function
Mechanism of Action
Glucose-facilitated sodium co-transport in the small intestine enhances water and electrolyte absorption, increasing net fluid uptake and reducing urinary fluid losses compared with water alone.
Physiological Role
Restore intravascular volume and correct deficits of water and electrolytes (principally sodium and chloride) to maintain plasma osmolality and circulating volume.
Primary Pathways
Performance / Health Relevance
By improving net fluid retention versus water, ORS can accelerate rehydration after exercise-induced losses and limit early urinary losses, which may be beneficial where sustained fluid retention is desirable.
Evidence Review
Practical Use & Dosage
- Minimum Effective Dose
- Replace measured fluid losses; trial examples include ingestion of 1 L in a single sitting or replacement of 100% of exercise-induced body-mass loss.
- Optimal Range
- Formulations used in trials included ~45 mmol sodium per litre with ~2.5% carbohydrate; reduced-osmolarity ORS formulations are commonly recommended in guidelines.
- Upper / Caution Level
- Not established from the provided abstracts; follow product instructions and clinical guidance for prolonged use.
- Timing
- Administer during or promptly after fluid loss (e.g. during diarrhoea or immediately after exercise).
- Best Format
- Powder to reconstitute or ready-to-drink solutions.
- Bioavailability
- Electrolytes and glucose in ORS are readily absorbed via intestinal transport mechanisms.
- Absorption Considerations
- Glucose enhances sodium (and hence water) absorption via SGLT1; beverage osmolarity and sodium content influence net fluid retention.
Safety & Interactions
Side Effects
- •Occasional nausea or vomiting may occur in some individuals
Contraindications
- None specified in provided abstracts; use caution in patients with complex electrolyte disturbances or severe vomiting where IV therapy may be required.
Drug Interactions
- •None specified in provided abstracts.
Who Should Avoid
- •Individuals unable to tolerate oral intake or with severe dehydration requiring intravenous fluids
Monitoring
Monitor clinical status and serum electrolytes in prolonged use or in patients with comorbidities; follow local clinical guidelines for severe dehydration.
Frequently Asked Questions
Auto-generated from indexed evidence — dosage, safety, interactions, and more.
When is Oral Rehydration Salts typically used or indicated?
Oral Rehydration Salts is most commonly used for: Rehydration after diarrhoea, Post-exercise rehydration, Replacement of acute fluid and electrolyte losses. Restore intravascular volume and correct deficits of water and electrolytes (principally sodium and chloride) to maintain plasma osmolality and circulating volume.
How does Oral Rehydration Salts work?
Glucose-facilitated sodium co-transport in the small intestine enhances water and electrolyte absorption, increasing net fluid uptake and reducing urinary fluid losses compared with water alone.
What is the recommended dose of Oral Rehydration Salts?
The optimal range is Formulations used in trials included ~45 mmol sodium per litre with ~2.5% carbohydrate; reduced-osmolarity ORS formulations are commonly recommended in guidelines.. with a minimum effective dose of Replace measured fluid losses; trial examples include ingestion of 1 L in a single sitting or replacement of 100% of exercise-induced body-mass loss.. Best taken: Administer during or promptly after fluid loss (e.g. during diarrhoea or immediately after exercise).. Upper / caution level: Not established from the provided abstracts; follow product instructions and clinical guidance for prolonged use..
What are the side effects of Oral Rehydration Salts?
Reported side effects include: Occasional nausea or vomiting may occur in some individuals. Monitoring: Monitor clinical status and serum electrolytes in prolonged use or in patients with comorbidities; follow local clinical guidelines for severe dehydration.
Does Oral Rehydration Salts interact with medications?
Known or theoretical interactions: None specified in provided abstracts.. Always check with a clinician before combining with prescription medication.
Who should avoid Oral Rehydration Salts?
Oral Rehydration Salts is generally not recommended for: Individuals unable to tolerate oral intake or with severe dehydration requiring intravenous fluids; and None specified in provided abstracts; use caution in patients with complex electrolyte disturbances or severe vomiting where IV therapy may be required..
How strong is the evidence for Oral Rehydration Salts?
Evidence level: Strong (overall score 75/100), based on 5 indexed studies on SuppIndex.
Research & References (5)
A randomized trial to assess the potential of different beverages to affect hydration status: development of a beverage hydration index.
Randomized trial in 72 healthy, fasted males comparing 1 L of various beverages; an oral rehydration solution produced significantly lower 4 h urine output and higher beverage hydration index at 2 h versus still water.
Post-Exercise Rehydration in Athletes: Effects of Sodium and Carbohydrate in Commercial Hydration Beverages.
Randomized, double-blind crossover trial in 26 athletes dehydrated ~2.6% body mass; compared water, a sports drink (18 mmol Na/L, 6% carbohydrate) and an ORS (45 mmol Na/L, 2.5% carbohydrate) for percent fluid retained over 3.5 h.
Diarrhoea in adults (acute).
Systematic review (to Jan 2010) of treatments for acute diarrhoea in adults; oral rehydration solutions (various formulations) were among interventions evaluated as part of the evidence synthesis.
Diarrhoea in adults (acute).
Earlier systematic review (to Jan 2007) of acute diarrhoea interventions in adults; oral rehydration solutions were listed among the interventions examined.
Systematic review on management of high-output enterostomy in children: An urgent call for evidence.
Systematic review on management of high-output enterostomy in children highlighted lack of evidence; conservative strategies mentioned include oral rehydration solution but no qualifying trials met inclusion criteria for this population.
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Research Overview
Strong EvidenceCite this ingredient
One-click citation export in APA, MLA, Chicago, BibTeX, or HTML. The URL below is stable and safe to link.
Stable URL
https://thesuppindex.com/ingredients/oral-rehydration-salts
SuppIndex. (2026). Oral Rehydration Salts: Evidence summary, dosage and clinical studies. Retrieved October 16, 2026, from https://thesuppindex.com/ingredients/oral-rehydration-salts
Based on 5 indexed studies · Evidence level: Strong.
Goal Ratings
Stack Compatibility
Can be used alongside other oral rehydration strategies; avoid concurrent excess hypotonic fluids which may impair electrolyte repletion.