How do you treat diarrhea in a child under 3?

Depends on how ill: For a child 1-2 years old with diarrhea (with or without vomiting), the amount of liquid a child drinks is even more important the what he is drinking. Small, frequent sips (while awake) work the best. That may mean 1/2 ounce (15 ml) every 30 minutes for a child with more diarrhea, to 2 ounces (60 ml) every hour for a baby with less diarrhea. Pedialyte works better than half-strength gatorade.