A common cold is an infection of your upper respiratory tract. It's relatively harmless — but it usually doesn't feel that way. If it's not a runny nose, sore throat and cough, it's watery eyes, sneezing and congestion. Or maybe all of the above. In fact, because any one of more than 200 viruses can cause a common cold, symptoms tend to vary greatly.

Unfortunately, if you're like most adults, you're likely to have a common cold two to four times a year. Children, especially preschoolers, may have a common cold as many as eight to 10 times annually.

The good news is that you or your child should be feeling better in about a week or so. If symptoms of a common cold aren't improving in that time, see your doctor to make sure you don't have a bacterial infection in your lungs, sinuses or ears.