Rehydration & electrolytes · Oral rehydration solution
Oral Rehydration Salts (ORS)
A balanced mixture of salts and glucose that restores fluids and electrolytes lost through diarrhoea, vomiting, or heavy sweating.
OTCKidney warningPaediatric useSenior precautionOverview & typical uses
A balanced mixture of salts and glucose that restores fluids and electrolytes lost through diarrhoea, vomiting, or heavy sweating.
Primary uses
- Preventing and treating mild to moderate dehydration
- Supporting recovery during acute diarrhoea and vomiting
How it works
The precise glucose-to-sodium ratio drives water absorption through the intestinal wall, restoring hydration effectively even during illness.
Available forms & strengths
- Oral powder sachet (Oral)
- Ready-to-drink solution (Oral)
General precautions & contraindications
Do not use if
- Severe dehydration needing intravenous fluids
- Ongoing vomiting preventing any oral intake — seek medical care
Pregnancy
Generally considered safe. Considered safe in pregnancy.
Breastfeeding
Generally considered safe. Safe during breastfeeding.
Kidney considerations
- Discuss with a clinician before use if you have severe kidney disease or need fluid restriction.
Paediatric use
Safe from infancy. Encourage frequent small sips.
Older adults
Encouraged during dehydrating illness; check for heart-failure fluid restrictions first.
Common side effects
- Usually well tolerated
- Mild nausea in some people
Serious warnings — seek help if these appear
- Electrolyte imbalance from incorrect preparation
Food & alcohol precautions
Do not substitute — they lack the correct salt balance and can worsen diarrhoea.
Storage, missed dose & overdose
Storage
Store dry sachets below 25 °C. Once mixed, use within 24 hours (refrigerated).
If a dose is missed
Take small sips frequently as tolerated — no fixed schedule.
Overdose
Overdose is uncommon with correct preparation. Do not alter concentrations.
What to monitor
- Seek medical care for signs of severe dehydration: very little urine, extreme dizziness, confusion, or inability to keep fluids down.
Frequently asked questions
Home-made recipes exist for emergencies, but pre-packaged ORS gives the most accurate salt balance.
Follow package guidance. In general, small frequent sips are more effective than large gulps.
Medical references
- WHO Oral Rehydration Salts formulation — World Health Organization
- UNICEF diarrhoea treatment guidance — UNICEF
Content last reviewed: 2025-01-01
Medical disclaimer
This information is for educational purposes only and should not replace professional medical advice. Please consult a licensed pharmacist or clinician for advice tailored to your personal circumstances.