Hand, foot and mouth disease usually doesn't require any diagnostic tests because the symptoms are so distinct.
It takes about three days for hand, foot and mouth to show itself. A child may have a fever, headache or sore throat and seem lethargic or irritable. But the symptoms of hand, foot and mouth that confirm its victory are a skin rash and mouth sores.
In a child showing all symptoms, you would notice red spots on palms and soles, and perhaps on knees, elbows or buttocks (hand, foot, mouth and rear-end disease is just too wordy). Inside his or her mouth, you would see what look like blisters with fluid in them. These sores can turn into painful ulcers. (There's a very similar condition called herpangina, but those blisters tend to be toward the back of the mouth instead of the front, and there's no skin rash involved [source: Perlstein].
Because it hurts to swallow, kids might not want to take in any fluids, so dehydration is a real danger. If a child isn't peeing much or has dark urine and has a dry tongue or sunken eyes, you need to see a doctor. In some cases, an IV is needed to deliver the proper amount of fluids.
It is possible for hand, foot and mouth disease to lead to serious complications. It's rare, but viral meningitis and encephalitis have both been known to follow, so trust your gut and call the doctor if symptoms get more serious and if a high fever and excruciating headache develop.
Some lucky people, particularly adults, don't show any symptoms at all, which is worrisome considering that the virus is very contagious, especially in the first week. That's why prevention is so important, which we'll learn more about on the next page.