Signs of dehydration in kids
Kids, and especially babies and toddlers, can lose fluid faster than adults. Here's what to watch for.
Written from AAP, federal and National Academies guidance and checked against each source. Medical review by a pediatric registered dietitian is in progress. Updated November 2026.
If your child is very drowsy, hard to wake, has sunken eyes, or has barely peed all day, call your pediatrician now. If they're unresponsive or struggling to breathe, call 911.
Early signs
The American Academy of Pediatrics lists these signs of mild to moderate dehydration:6
- Less playful or active than usual
- Peeing less often (in babies, fewer than six wet diapers a day)
- Dry, sticky mouth
- Fewer tears when crying
- Sunken soft spot on the head in babies and toddlers
- Fewer bowel movements if the cause is vomiting or not drinking, or loose stools if the cause is diarrhea
Signs of severe dehydration
In addition to the early signs:6
- Much fussier than usual
- Unusually sleepy or drowsy
- Sunken eyes
- Cool, blotchy or discolored hands and feet
- Wrinkled-looking skin
- Peeing only once or twice a day
The AAP advises calling your pediatrician right away if any of these warning signs appear.
What usually causes it
- Stomach bugs. Vomiting and diarrhea are the most common cause in young kids.
- Fever. Kids lose more water when they run hot.
- Heat and sports. Long practices, hot cars and summer camps.
- Not drinking. A sore throat, mouth sores or just being too busy to stop.
What to do
- For mild cases in otherwise healthy kids, offer small, frequent sips of fluid.
- When a child is vomiting or has diarrhea, ask your pediatrician about an oral rehydration solution. These are made for replacing fluid during illness. Sports drinks and juice aren't the same thing and can make diarrhea worse.
- Babies under 6 months should keep getting breast milk or formula. Don't give them plain water unless your pediatrician says to.
Preventing it
Most dehydration in healthy kids is prevented with water at meals, a water bottle within reach, and extra water on hot or active days. See how much water by age and sports and heat.
Common questions
How can I tell if my toddler is dehydrated?
Watch for fewer wet diapers or bathroom trips, a dry mouth, no tears when crying, less energy than usual, and a sunken soft spot on the head. Very sleepy, sunken eyes or peeing only once or twice a day are signs of severe dehydration. Call your pediatrician.
Should I give my child a sports drink when they're sick?
Not usually. Ask your pediatrician about an oral rehydration solution instead. Sports drinks have more sugar and less of the salts kids lose during vomiting and diarrhea.