Symptoms

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