What to expect from oral rehydration therapy for gastroenteritis

Gastroenteritis irritates the stomach and bowel, so fluid can leave the body through vomiting and loose stools. An oral rehydration solution provides water, glucose and salts in proportions that help absorption. It does not directly remove the infection. You may still have cramps or loose stools while hydration improves, but alertness, thirst and urination should be watched closely. See [Gastroenteritis](/conditions/gastroenteritis/) for broader information.

Mix the product with the exact volume of safe water stated on the label. Sip regularly, especially after a loose stool, rather than taking a large glass quickly. After vomiting, restart with tiny sips and increase gradually if they stay down. Keep breastfeeding if applicable, and return to ordinary foods as tolerated. Use the guidance on [Oral Rehydration Therapy](/treatments/acute-and-urgent-care/oral-rehydration-therapy/) for preparation and use.

Seek urgent care for confusion, fainting, severe weakness, no or very little urine, inability to swallow fluids, repeated vomiting, blood in stool, or severe abdominal pain. Fever with a stiff neck, a marked change in behaviour, or worsening symptoms also needs prompt assessment. Infants and older adults can deteriorate without obvious thirst, so use a lower threshold for advice.

Ask how to judge hydration, whether a child needs a different plan, when normal meals should resume, and whether any medicine could worsen vomiting or diarrhoea.