Thirst isn't always a reliable early indicator of the body's need for water. Many people, particularly older adults, don't feel thirsty until they're already dehydrated. That's why it's important to increase water intake during hot weather or when you're ill. The signs and symptoms of dehydration also may differ by age. Infant or young child  Dry mouth and tongue No tears when crying No wet diapers for three hours Sunken eyes, cheeks Sunken soft spot on top of skull Listlessness or irritability  Adult  Extreme thirst Less frequent urination Dark-colored urine Fatigue Dizziness Confusion  When to see a doctor Call your family doctor if you or a loved one:  Has had diarrhea for 24 hours or more Is irritable or disoriented and much sleepier or less active than usual Can't keep down fluids Has bloody or black stool 
thirst isn't reliable early indicator body's need water  people  older adults  don't feel thirsty they're dehydrated  that's it's important increase water intake hot weather you're ill  signs symptoms dehydration may differ age  infant young child  dry mouth tongue tears crying wet diapers hours sunken eyes  cheeks sunken soft spot top skull listlessness irritability  adult  extreme thirst frequent urination dark-colored urine fatigue dizziness confusion  see doctor call family doctor loved one:  diarrhea 24 hours irritable disoriented sleepier active usual can't keep down fluids bloody black stool 
dehydration