How Can Nasal Obstruction Cause Post-Nasal Drainage?

Before talking about the nose, consider the way some home humidifiers work. There is a sponge, water supply, and airflow. Humidification occurs by having a fan blow air though the sponge that is soaked by a constant water supply. As the air passes through the wet sponge, evaporation occurs resulting in air humidification.

Well, the same thing occurs inside the nose. In a normal nose, about one liter of moisture is produced by the nasal mucosa every day (water supply). This nasal moisture production is what allows the air to be humidified as a person breathes (the fan) through the nose.

However, when the nose is obstructed preventing a steady airflow, there is a corresponding reduction in evaporation allowing for more moisture to be present inside the nose. With increased moisture, it may lead to the perception of increased post-nasal drainage.

So, how can post-nasal drainage be corrected in this situation?

Well, one can try to decrease nasal moisture production using medications like decongestants, anti-histamines, and/or nasal sprays. Or, one can try to alleviate the nasal obstruction to increase nasal airflow leading to increased evaporation thereby reducing the amount "drainage" (which actually is normal "water supply").

Alleviating nasal obstruction can also occur with decongestant, allergy, and nasal spray medications, but if there's not much improvement, one can consider surgical options if there are anatomic factors present.

Such intra-nasal anatomic obstructions include deviated septum, turbinate hypertrophy, adenoid hypertrophy, nasal polyps, etc.

There is a specific surgical procedure that can address each of these issues if present.

Of course, nasal obstruction does not automatically lead to post-nasal drainage. But it is only one of many other factors that may be present that can lead to this complaint.