As anyone who’s had a toddler knows, they’re incredibly demanding creatures. Armed with an insatiable desire to eat and/or destroy just about everything in their path, these walking embodiments of unchecked ego can be a handful. Especially when they have colds. There’s nothing quite as trying as a toddler with a head cold, stuffed up nose, and ever present rivers of mucus flowing from each nostril. Because most toddlers can’t blow their own noses, the constant wiping and suctioning can be a chore. But runny noses serve a useful purpose. When we catch a cold, the virus stimulates membranes in the nose to produce clear mucus. When mucus streams out the nostrils or is propelled by a forceful blow, it carries germs from the nose and sinuses. When the body’s immune system starts to fight the cold virus, it turns the mucus white or yellow, which is the body’s way of letting you know it’s been infected.