Could my babies runny nose be due to an allergy?

Q: My 6-month-old baby often has either a runny or a congested nose. Could this be due to an allergy?

A: Contrary to common belief, which blames respiratory allergies for symptoms that are actually caused by lingering colds, allergies are relatively rare in children and even more so in infants. In fact, it takes several years of exposure for a child to develop a reaction to an allergen like pollen.

Nasal symptoms are very noticeable in infants because young babies are lying down most of the time, causing mucus to accumulate in the back of the nose. And even when awake, they don't clear their breathing passages by coughing, sneezing or swallowing, as someone who's older would. Finally, the tininess of a baby's nasal passages ensures that even a little blockage is clearly audible.

One caution: Call your pediatrician if your baby develops fast or difficult breathing or wheezes when she exhales. These can be symptoms of respiratory syncytial virus (RSV), which can lead to serious infection.