How does oral rehydration therapy work?

Diarrhoea and vomiting can remove water and electrolytes such as sodium from the body. In the small intestine, glucose and sodium are transported together; water follows them across the intestinal lining. This allows an oral rehydration solution to replace fluid and salts even when some diarrhoea continues. It does not remove the infection or stop every episode of vomiting.

The mixture needs the correct balance. Commercial sachets should be prepared with the exact amount of safe water stated on the packet. Very concentrated, diluted or homemade mixtures can contain the wrong salt or sugar level and may be unsafe.

Prepare the solution exactly as directed and offer frequent small sips. If vomiting occurs, pause briefly and restart with smaller amounts. Continue breastfeeding when relevant and offer suitable food as the person improves. Keep prepared solution covered and follow the packet’s storage instructions; discard it when the stated time has passed. Do not add juice, extra sugar or salt.

Get urgent help for confusion, fainting, severe weakness, inability to drink, very little urine, blood in stool, severe abdominal pain or breathing difficulty. A baby, older adult or person with a serious medical condition can become dehydrated quickly and should be assessed early. Contact a clinician when vomiting prevents fluids staying down, diarrhoea persists, or signs of dehydration are worsening despite oral rehydration.

Ask which product is suitable, how much and how often to offer it, and whether another treatment is needed for the cause of fluid loss. Check whether kidney, heart or other health problems require a modified plan.