Kids with the flu may have diarrhea and vomiting, which can make them dehydrated quickly. Give your child a special solution like Pedialyte, clear soups, water, or juice mixed with water. Start with a few teaspoons every 5 minutes. When they can drink without throwing up, try giving larger amounts. If they vomit more than once, if they are not urinating as much as usual, or if they look sick, call the doctor.