One thing that you learn very early on as a parent is that you HATE to see your children sick. Any parent would do anything to make their children better. The other thing is that sometimes you can get so laser focused on one particular symptom that you may miss something that is extrememly important. Any time your child has a decrease in fluid intake: not eating, drinking, vomitting, diarrhea, it is important that you closely monitor for signs and symptoms of dehydration. Much like the elderly population, children dehydrate quickly. The best way to monitor hydration status is to be aware of how often your child is urinating, either through monitoring how often you are changing a wet diaper or how often they are going to the bathroom to urinate. If the body is producing urine there is a significant chance that you child is staying hydrated. The body will not let go of excess fluid if it is starved for it. For younger children we really want to see a wet diaper every 4-6 hours with older children we want to see them go to the bathroom at least every 6-8 hours. Another way to monitor hydration status would be to check the inside of your childs mouth. If it feels moist, the child is reasonably hydrated. If the inside of the mouth feels dry and sticky, it is time to start to think about ways to prevent further dehydration. Also, if a child is crying but is unable to produce any tears, this might indicate an issue with the childs hydration status. In infants, a sunken soft spot can also be a late indicator of poor hydration status.
When your child is ill it is very important to be vigilant of their hydration status. This is something that is very easily monitored at home but can be a key indicator of how ill your child is and can determine the need to seek further medical care. Any time your child becomes lethargic, gray or ill looking, or overall your gut tells you something isn't right, it is time to contact your childs doctor.