(HealthDay News) -- A runny nose usually starts when your child's cold is on the mend, says the American Academy of Family Physicians.
Mucus from a runny nose helps wash the cold virus out of the nose and sinuses. After a few days, the mucus may change to a white or yellow color, then to green.
A runny nose usually does not need to be treated. However, a cool mist vaporizer or over-the-counter decongestant medicine may help. The AAFP suggests checking with your child's doctor to see which medicines are okay.