The most important of treating viral gastroenteritis in children and adults is to prevent severe loss of fluids (dehydration). This treatment should begin at home.
Stay Hydrated. The best fluid to use to treat/prevent dehydration is an oral rehydration solution like Pedialyte.
Count wet diapers or frequency of urination.
The goal is to offer enough fluid so that the child urinates 3-4x in a 24h period. They do not need to produce a large quantity of urine, so the diapers don’t have to be saturated. Urine just has to be produced.
When your child is expressing interest in food start with a bland, starchy carb diet (bananas, rice, applesauce, and toast- the BRAT diet). Start with small frequent meals and do not pressure your child to eat.
The anus and buttocks can become quite irritated if exposed to very acidic stool. Clean the buttocks and anus after bowel movements with water. Alternatively, soak the child in a bathtub of warm water with baking soda (1/4 cup) sprinkled in. Apply a thick barrier ointment to the skin such as Desitin Original.