Adult Rehydration Guidelines

General Recommendations

For general rehydration in healthy adults with mild dehydration, the European Society for Clinical Nutrition and Metabolism recommends encouraging any preferred beverages including water, tea, coffee, fruit juice, sparkling water, carbonated beverages, or even lager, as oral rehydration solutions and sports drinks are not indicated for simple low-intake dehydration 1
The European Society for Clinical Nutrition and Metabolism suggests that water, hot or iced tea, coffee, fruit juice, carbonated beverages, and lager are preferred beverages for low-intake dehydration 1
The European Society for Clinical Nutrition and Metabolism advises against using oral rehydration solutions and sports drinks for low-intake dehydration, as they are designed for electrolyte replacement in diarrhea or vomiting, not simple dehydration 1, 2

For mild diarrhea without dehydration, the European Society for Medical Oncology recommends diluted fruit juices, flavored soft drinks, glucose-containing beverages, and soups or broths rich in electrolytes 3, 4, 5, 6
For moderate to severe diarrhea with dehydration, the World Health Organization recommends using oral rehydration solutions with 65-70 mEq/L sodium and 75-90 mmol/L glucose, and a total fluid intake of 2200-4000 mL/day 3, 4
The European Society for Medical Oncology notes that oral rehydration solutions are appropriate for diarrheal illness because they replace electrolytes lost through stool, but are contraindicated for simple dehydration from inadequate intake 3, 4, 1, 2

The European Society for Clinical Nutrition and Metabolism recommends identifying the cause of dehydration, assessing severity, and monitoring response to guide beverage selection 1
For low fluid intake, the European Society for Clinical Nutrition and Metabolism suggests using preferred beverages, while for diarrhea or vomiting, oral rehydration solutions should be used for moderate to severe cases 1, 3, 4

The European Society for Clinical Nutrition and Metabolism advises against confusing dehydration types, as low-intake dehydration and volume depletion from diarrhea require opposite fluid strategies 1, 2
The European Society for Medical Oncology recommends avoiding caffeinated beverages during diarrheal illness, as they can worsen symptoms 5, 6
The European Society for Clinical Nutrition and Metabolism notes that older adults may have impaired thirst mechanisms and require scheduled fluid intake rather than ad-lib drinking 1
The European Society for Medical Oncology advises against relying on lactose-containing products during prolonged diarrhea, as they may worsen symptoms due to secondary lactase deficiency 5, 6