Can tea consumption cause dehydration in patients?

Tea Does Not Cause Dehydration

Tea is a hydrating beverage and does not cause dehydration in patients—it should be actively encouraged as an appropriate fluid choice for maintaining hydration status. 1

Evidence-Based Recommendation

The ESPEN (European Society for Clinical Nutrition and Metabolism) guidelines explicitly state that tea (both hot and cold) is among the drinks that provide a hydrating effect on the body and should be offered to patients according to their preferences. 1

Dispelling the Caffeine Myth

There is a common myth that must be dispelled: caffeinated beverages like tea cause dehydration—this is categorically false. 1

• Despite widespread concerns about the "dehydrating" effects of caffeine, good evidence from randomized controlled trials demonstrates that tea does not cause dehydration. 1
• The hydration potential of hot or iced tea is very similar to that of plain water. 1
• Research shows that black tea, in typical consumed amounts, offers similar hydrating properties to water with no significant differences in blood or urine measurements of hydration status. 2

The Science Behind Caffeine and Hydration

• Acute caffeine ingestion only produces diuretic effects at very high doses (at least 250-300 mg, equivalent to 5-8 cups of tea), and only in individuals who have been deprived of caffeine for days or weeks. 3
• Profound tolerance to any diuretic effects of caffeine develops rapidly in regular consumers. 3
• Doses of caffeine equivalent to normal servings of tea appear to have no diuretic action. 3
• Even in mildly dehydrated individuals, green tea ingestion does not worsen hydration levels and effectively reduces negative fluid balance during recovery from mild hypohydration. 4

Clinical Application

For General Hydration

Tea should be included in the range of appropriate beverages offered to patients for hydration purposes. 1, 5

• Water, sparkling water, flavored water, hot or cold tea, coffee, milk drinks, fruit juices, soups, and soft drinks are all hydrating. 1
• Patients do not need to drink plain water to stay hydrated—this is a myth. 1
• Beverage selection should be based on patient preferences to encourage adequate fluid intake. 1

For Older Adults

Tea is particularly valuable for older adults who are at high risk of dehydration. 1

• In the UK, coffee and tea intake each make up around 10% of drinks intake in free-living older adults, making them important fluid sources. 1
• Twenty percent of UK care home residents report coffee as their favorite drink, and 50% drink coffee daily—similar patterns exist for tea consumption. 1
• Offering a variety of drinks including tea is more enjoyable than always drinking water and promotes better overall fluid intake. 1

Special Considerations

If continence is a concern, decaffeinated tea may be tried, but is not necessary unless found helpful. 1

• The evidence does not support routine avoidance of caffeinated tea for continence issues. 1
• Decaffeinated options should only be used if they prove beneficial for the individual patient. 1

Common Pitfall to Avoid

Do not confuse low-intake dehydration with volume depletion from diarrhea or vomiting. 5

• For simple dehydration from inadequate fluid intake, tea and other preferred beverages are appropriate. 5
• For diarrheal illness with electrolyte losses, oral rehydration solutions (not tea) are indicated for moderate to severe cases. 5
• Tea is contraindicated during active diarrheal illness as caffeinated beverages can worsen symptoms. 5

Bottom Line for Clinical Practice

Tea contributes to daily fluid intake and helps maintain hydration status. 1, 2 Healthcare providers should actively encourage tea consumption as part of a varied fluid intake strategy, particularly in populations at risk for dehydration such as older adults. 1 The outdated belief that tea causes dehydration should be abandoned in clinical practice. 1