Recommended Beverages for Adult Rehydration
For general rehydration in healthy adults with mild dehydration, encourage any preferred beverages including water, tea, coffee, fruit juice, sparkling water, carbonated beverages, or even lager—oral rehydration solutions and sports drinks are NOT indicated for simple low-intake dehydration. 1
Context-Specific Recommendations
For Low-Intake Dehydration (Non-Diarrheal)
Preferred beverages:
- Water (plain or sparkling) 1
- Hot or iced tea 1
- Coffee 1
- Fruit juice 1
- Carbonated beverages/sodas 1
- Lager 1
Avoid:
- Oral rehydration solutions (ORS) - these are designed for electrolyte replacement in diarrhea/vomiting, not simple dehydration 1
- Sports drinks - similarly inappropriate for low-intake dehydration 1
The key principle here is that low-intake dehydration requires hypotonic fluids to dilute elevated osmolality, not electrolyte replacement 1. The ESPEN geriatrics guideline explicitly states this distinction with strong consensus (100%) 1.
For Diarrheal Illness
The approach differs dramatically based on severity:
Mild diarrhea (no dehydration):
- Diluted fruit juices 1
- Flavored soft drinks 1
- Glucose-containing beverages (lemonades, sweet sodas) 1
- Soups and broths rich in electrolytes 1
- Saltine crackers alongside fluids 1
Moderate to severe diarrhea (with dehydration):
- WHO oral rehydration solutions (65-70 mEq/L sodium, 75-90 mmol/L glucose) 1
- Commercial ORS formulations 1
- Total fluid intake: 2200-4000 mL/day 1
Critical distinction: In diarrheal illness, ORS is appropriate because you're replacing electrolytes lost through stool 1. In simple dehydration from inadequate intake, ORS is contraindicated 1.
For Exercise-Related Dehydration
During exercise:
- Fluids containing 20-30 mEq/L sodium 2
- Volume: 200-800 mL/hour 2
- Carbohydrate-containing beverages for high-intensity exercise 2
Post-exercise rehydration:
- Skim or low-fat cow's milk appears superior to water for volume restoration 3
- Water is acceptable but less effective than milk 3
- Consume 1.5 L per kg of weight lost 2
Avoid:
- Excessive sodium-free fluids (risk of exercise-induced hyponatremia) 2
Clinical Algorithm for Beverage Selection
Step 1: Identify the cause of dehydration
- Low fluid intake → Use preferred beverages (water, tea, coffee, juice, etc.) 1
- Diarrhea/vomiting → Use ORS for moderate-severe cases 1
- Exercise → Use sodium-containing fluids during activity, consider milk post-exercise 2, 3
Step 2: Assess severity
- Mild (appears well) → Oral fluids of choice 1
- Moderate-severe (appears unwell) → Consider IV/subcutaneous fluids alongside oral intake 1
- Severe with inability to drink → IV fluids required 1
Step 3: Monitor response
- Reassess hydration status regularly until corrected 1
- If no improvement in 48 hours, seek medical evaluation 1
Common Pitfalls to Avoid
Do not confuse dehydration types: Low-intake dehydration and volume depletion from diarrhea require opposite fluid strategies—hypotonic versus isotonic/ORS respectively 1, 4. Using ORS for simple dehydration is inappropriate and reflects a fundamental misunderstanding of the pathophysiology 1.
Avoid caffeinated beverages in diarrhea: While coffee is acceptable for low-intake dehydration 1, caffeine-containing drinks (including colas) should be avoided during diarrheal illness 1.
Do not rely on thirst alone in elderly: Older adults may have impaired thirst mechanisms and require scheduled fluid intake rather than ad-lib drinking 1.
Avoid lactose during prolonged diarrhea: Milk products may worsen symptoms due to secondary lactase deficiency 1.