Sinus infection is another cause of childhood runny nose and should be considered if the nasal drainage lasts longer than the seven to ten-day uncomplicated viral cold. However, the criteria for sinusitis in children is more stringent than in adults, primarily because upper respiratory illness so frequently occurs in the normal child. A number of conditions in children, rarely seen in adults, can lead to excessive nasal drainage. The adenoids sit in the back of the nose in an area called the nasopharynx. In children, they can be large and manifested by loud snoring and a nasal voice.
Adenoids tend to shrink during the teenage years, and are usually gone by age eighteen.
Chronic infection of the adenoids can itself cause a runny nose, or may secondarily infect the sinuses. Large tonsils or chronic tonsil infection can also lead to sinus infections in children. A rare congenital condition, usually diagnosed early in life, is called choanal atresia, in which there is blockage at the back of the nasal passages. If there is a narrowing rather than complete blockage, we use the term choanal stenosis. When this occurs, the mucus that the nose and sinuses produce cannot drain backward and thus pours out the front of the nose.