--- title: "Oral rehydration salts: Uses & Side Effects | HealthAnswers" description: "Oral rehydration salts are pharmacy sachets that replace fluids and salts lost to diarrhoea and vomiting; how they work, dosing, and dehydration warning…" url: https://healthanswers.co.uk/treatments/oral-rehydration-salts/ robots: noindex --- # Oral rehydration salts: Uses & Side Effects | HealthAnswers Treatments Oral rehydration salts are pharmacy sachets that replace fluids and salts lost to diarrhoea and vomiting; how they work, dosing, and dehydration warning signs. Written by HealthAnswers editorial team Medically reviewed by [HealthAnswers UK doctor review panel](https://healthanswers.co.uk/our-doctors/) Reviewed 3 July 2026 ## Quick answer What are oral rehydration salts used for? Oral rehydration salts (ORS) are sachets of glucose and salts dissolved in water to replace fluids lost through diarrhoea and vomiting. They rehydrate more effectively than water alone and are especially useful for children, older people and anyone with heavy fluid loss. ## Who is this page for? This page is for people in the UK who want a plain-English overview of Oral rehydration salts, including when to seek help and what NHS care usually involves. It explains general information, not what is wrong with you personally. ## Who should skip this page? Skip this page if you need a diagnosis, a prescription, or emergency care. It cannot replace a GP, pharmacist, NHS 111 or 999. If you are in immediate danger, call 999; for urgent advice that is not life-threatening, call 111 in England, Scotland or Wales, or use your GP out-of-hours service in Northern Ireland. On this page 4 sections ## Key facts about oral rehydration salts - ORS sachets replace fluids and salts lost in diarrhoea and vomiting. - They rehydrate the body more effectively than water alone. - They are especially useful for children, older people and anyone with heavy fluid loss. - They are available from any pharmacy and should be made up exactly as directed. ## What are oral rehydration salts? Oral rehydration salts (ORS) are pharmacy sachets containing a precise blend of glucose and essential salts. Dissolved in water, they replace what diarrhoea and vomiting strip out — not just fluid, but the sodium, potassium and glucose the body needs to hold onto that fluid. It is a simple treatment with a remarkable record: globally, ORS has saved millions of lives. ## Why oral rehydration salts work better than water Water alone replaces volume but not salts, and during diarrhoea the gut absorbs plain water poorly. The glucose in ORS actively transports sodium — and with it water — into the body, so rehydration is faster and more complete. That difference matters most in young children, older people and anyone losing a lot of fluid. ## How to use oral rehydration salts properly - dissolve each sachet in the exact amount of water stated — never stronger, never weaker - sip frequently rather than gulping - take more after each loose stool or vomit, as the pack directs - for children, follow the age-specific guidance or ask a pharmacist Avoid improvising home mixes: the proportions are the point, and getting them wrong — particularly too much salt or sugar — can do harm, especially in children. ## When to see a GP about dehydration ORS supports recovery but does not replace vigilance. Contact a GP or 111 if fluids will not stay down, urine is dark and scarce (or nappies stay dry), drowsiness or dizziness develops, there is blood in the diarrhoea, or things are not improving within a few days — and act sooner for babies, frail older people and anyone with a weakened immune system. ## ! Important safety information for oral rehydration salts Use ORS alongside watching for dehydration, not instead of it. Contact a GP or NHS 111 if you or your child cannot keep fluids down, show signs of dehydration (dark urine, dizziness, drowsiness, or few wet nappies in babies), have blood in the diarrhoea, or are not improving after a few days. Seek **urgent** help for a baby, a frail older person, or anyone with a weakened immune system who is becoming more unwell. ## Common questions about oral rehydration salts How do oral rehydration salts work? The precise mix of glucose and salts matches what the gut absorbs best — the glucose actively helps pull water and sodium into the body. That is why ORS rehydrates faster and more completely than water alone during diarrhoea. How do I use ORS sachets? Dissolve a sachet in the exact amount of water stated — never stronger or weaker — and sip frequently. After each loose stool or vomit, take more as directed. For children, follow the pack's age guidance or a pharmacist's advice. Can I make my own rehydration drink? Pharmacy sachets are strongly preferred because the proportions matter — too much salt or sugar can make things worse, especially for children. Sachets are cheap, accurate and widely available. Who benefits most from ORS? Young children, older people, and anyone with heavy or prolonged diarrhoea and vomiting — the groups who dehydrate fastest. For mild cases in healthy adults, water and normal drinks taken little and often may be enough. ## Sources - [NHS — Diarrhoea and vomiting](https://www.nhs.uk/conditions/diarrhoea-and-vomiting/)