Glands in your nose and throat continually produce mucus. Mucus is a thick, wet substance that moistens and cleans the nasal membranes, humidifies air, traps and clears inhaled foreign matter, and fights infection. Normally, you don’t notice the mucus from your nose because it mixes with saliva, drips harmlessly down the back of your throat, and you swallow it.
When your body produces more mucus than usual or it’s thicker than normal, it becomes more noticeable. Excess mucus can come out of the nostrils resulting to a runny nose. When the mucus runs down the back of your nose to your throat, the condition is called postnasal drip.
The excess mucus that triggers postnasal drip has many possible causes. The most common are colds, flu, allergies, sinusitis, a deviated septum (misalignment of the wall that separates the two nostrils), and weather changes.
