Sometimes, when mucus flows from the nasal cavity, people find it psychologically unpleasant. When there's a secretion in the throat, they instinctively want to cough it out, especially during meals when there’s an obvious foreign body sensation in the throat. What causes this?

The doctor explains that these issues are mainly due to the nasal cavity's self-cleaning function weakening with age. The mucous blanket in the nasal cavity relies on the movement of cilia, and there are generally two scenarios in which the mucous blanket may signal a foreign body sensation. The first is when you're sick. After falling ill, the secretion increases, and inflammation or tumors produce abnormal secretions, which can cause a noticeable presence of mucus.

The second scenario occurs when there is less secretion. As people age, the secretion function of the cells weakens, and the tissue becomes drier, especially if the surrounding air is also dry. In such cases, the humidity of the mucous blanket decreases, its fluidity weakens, it dries out, and you start to feel mucus in your throat.

Some issues can be easily identified through medical examinations. A doctor can look at the characteristics of the secretion and determine whether the nasal airflow has increased or if there is excessive ventilation in the nasal cavity. If the nasal turbinates shrink, causing atrophic rhinitis, or if the nasal cavity narrows, it can also become dry.

You might wonder how a narrowed nasal cavity can also become dry. When the nasal cavity narrows, the airflow through it accelerates. We say that fast airflow creates greater negative pressure. When the airflow speeds up, the negative pressure increases, and the rapid airflow causes the nasal cavity to dry out.

A common scenario is in patients who snore or have sleep apnea. Due to narrowed airways, their airflow becomes more forceful at night. We've measured airflow speeds, and the values are several times higher than normal airflow—very rapid. Additionally, because they snore at night, they wake up with a dry nasal cavity and feel like there's mucus in the back of the nose. In fact, clinical examination can reveal whether the nasal cavity is narrow or if a wide nasal cavity has caused postnasal drip.

Although the condition of postnasal drip can be somewhat complex, there's no need to worry. Many patients are visiting hospitals due to postnasal drip nowadays. The main cause is aging, which weakens the nasal cavity's self-cleaning ability, leading to such conditions. Therefore, long-term or even lifelong care of the nasal cavity is necessary.

It's also important to keep the nasal cavity moist and drink plenty of water. Drinking water enters through the throat, and some of the moisture will evaporate, and the water vapor entering the nasal cavity will make it feel more comfortable. You can also regularly perform nasal irrigation, but be sure to pay attention to the temperature of the water when doing nasal irrigation, and try to use warm water for rinsing.