[header] How to treat a child who can't keep food down [title] Keep your child hydrated. [step] A lot of liquid is lost through vomiting. You should strive to keep your child hydrated for the duration of his sickness. 
Water is the best liquid, but varying drinks will help encourage fluid intake. [substeps] Encourage your child to take small, slow sips of liquids frequently, every five to 10 minutes if possible.