Oral Rehydration Therapy

Oral rehydration therapy replaces water and essential salts after fluid loss from illness, heat, or exertion.

It uses a prepared solution containing glucose and electrolytes. In the intestine, glucose helps the body absorb sodium and water together, which can make small, repeated drinks more useful than plain water alone during ongoing diarrhoea or vomiting.

Some people notice less thirst, a wetter mouth, or more frequent urination as fluid replacement takes effect. Improvement depends on how much fluid has been lost and whether vomiting or diarrhoea is continuing. Keep taking small sips; feeling better does not necessarily mean fluid losses have stopped.

The solution itself is usually well tolerated. Drinking a large amount quickly can worsen nausea or trigger vomiting, so small frequent sips are often easier. Mixing a sachet with too little water, adding extra sugar or salt, or using a homemade mixture with uncertain measurements can upset the electrolyte balance.

Use the solution while fluid losses continue and until you can comfortably drink and eat normally. For short-lived stomach illness, this may be a brief measure. A clinician should guide use when dehydration is substantial, symptoms persist, or a medical condition affects how your body handles fluids or salts.

Choose a commercially prepared oral rehydration solution when available and follow its mixing directions exactly. Use safe drinking water, prepare only what you expect to use soon, and do not substitute sports drinks, soft drinks, juice, or heavily salted broths for an oral rehydration solution.

Oral rehydration therapy can be useful with dehydration related to gastroenteritis, food poisoning, traveller's diarrhoea, or heat exhaustion. Cholera and norovirus infection can also cause rapid fluid loss. Babies, children, older adults, and people who cannot keep fluids down may need earlier clinical assessment because dehydration can worsen quickly.

Start with a correctly prepared solution. Take small, frequent sips rather than forcing a full glass. If vomiting occurs, pause briefly and restart with smaller amounts. Continue usual foods when appetite returns unless a clinician has advised otherwise. Watch for urination, alertness, thirst, and the ability to keep fluids down.

As hydration improves, thirst and dry mouth may ease and urine should become less concentrated. Rest, cooling down after heat exposure, and restarting light meals as tolerated can help recovery. Continue to monitor symptoms rather than relying on a single sign of improvement.

Severe dehydration can require assessment and intravenous fluids. Seek urgent care for confusion, collapse, persistent vomiting, severe weakness, or signs of dehydration in an infant. People with kidney disease, heart failure, or a prescribed fluid restriction should seek personalised advice before increasing fluids or electrolyte intake.

Intravenous fluid therapy may be used when someone cannot drink enough, is repeatedly vomiting, or needs faster monitored replacement. Treatment also depends on the cause of the fluid loss; a clinician may assess for infection, heat illness, or another condition that needs separate care.

A GP, urgent care clinician, or pharmacist can help you choose an appropriate solution and decide whether home treatment is suitable. Bring details about fluid intake, vomiting or diarrhoea, medicines, medical conditions, and changes in urination when seeking care.