Overview of rehydration in adults

Rehydration is the most important aspect of managing acute gastroenteritis. All adults with gastroenteritis should have their hydration status assessed so that appropriate rehydration can be given—see Assessing adults for dehydration.

The route of rehydration in adults with gastroenteritis is guided by the:

• degree of dehydration (see Assessing clinical and laboratory features of dehydration in adults)
• presence of complications and comorbidities
• goals of care in the patient.

Patients with minimal or no dehydration should be encouraged to continue eating and drinking as tolerated (see Diet and feeding during gastroenteritis). In patients without risk factors for dehydration, eating and drinking is usually sufficient to replace fluid and electrolyte loss.

Patients with a higher degree or risk of dehydration can usually be treated with oral rehydration. Intravenous or subcutaneous rehydration may be required for severe dehydration or if dehydration does not improve with oral rehydration.

Close attention to fluid and electrolyte balance is particularly required in frail older patients, in patients on fluid restriction, patients with heart failure or those receiving renal replacement therapy.