Post nasal drip is a sensation of mucous build up in
throat. Sometimes you may even feel a dripping sensation from back of your nose. The cause is over-production of mucous by glands in nose and in throat.
At a healthy level those glands produce around two quarts of mucous each day. Most, if not all, of that is swallowed without knowing it. The mucous, however, serves a healthy purpose at this level, cleaning and moistening nasal passages, trapping foreign matter that has been inhaled, moistening and humidifying air you breathe, and even fighting infection.
At an unhealthy level, mucous becomes either excessively thick or excessively thin, possibly due to irritation, infection, or allergic reaction. Those who have difficulty swallowing normally may especially need to be cautious, because build-up may fester and cause infection.
There are some things we cannot control. For example, more than 90% of irritants and bacteria which cause infection enter body through nose. Much of it will remain in nasal passages and seek to live and grow there.
The body will react to infection by sending its defense system of white blood cells to nasal passages to trigger more mucous production in order to “wash out” bacteria, irritants, or foreign matter. But this tends to further congest nose. What makes matters worse, we often blow our noses, swallow phlegm, or cough to relieve congestion, but these actions force bacteria to other places in body, including sinuses, throat, or ears, causing further sickness.
