All heat reactions are caused by an excessive loss of water through sweating. Make sure your child drinks a lot of cool water whenever she is working or exercising in a hot environment.
Water is ideal for replacing lost sweat.
Very little salt is lost in sweat. Special glucose-electrolyte solutions such as Gatorade offer no advantage over water unless your child has been exercising for over an hour. Have your child take 5-minute water breaks every 25 minutes in the shade. Encourage your child to drink water even if he is not thirsty. He may not feel thirsty until he is almost dehydrated.