Hacking and Coughing: Is Sticky Phlegm a Distress Signal from Your Lungs?

The 'dampness-phlegm' described in Donguibogam can be seen as encompassing the concepts of bronchial mucus hypersecretion and chronic inflammation explained in modern medicine. In our bronchi, mucus is secreted to protect the lungs from external foreign matter; this mucus is naturally moist and soft, capturing foreign particles and discharging them outside the body through ciliary movement. However, when exposed to continuous irritation such as fine dust, smoking, allergens, and viral or bacterial infection, or when the function of mucus-secreting glands (goblet cells, submucosal glands) is hyperactivated due to an autonomic nervous system imbalance, mucus is excessively secreted and its properties become thick and sticky. This hypersecreted sticky mucus hinders bronchial ciliary movement and reduces the ability to expel foreign substances, leading to a vicious cycle that worsens inflammation within the bronchi. Chronic inflammation activates immune cells, and various inflammatory mediators (cytokines, chemokines, etc.) secreted during this process stimulate further mucus secretion and increase mucus viscosity. Just as Donguibogam observed that dampness-phlegm accumulates waste in the body like stagnant water spoiling, modern medicine also explains that excessive, sticky mucus can worsen the bronchial environment and become fertile ground facilitating bacterial growth. Furthermore, lung health is not confined solely to the respiratory system. It is also closely connected to the neuroendocrine system. Chronic stress stimulates corticosteroid secretion, which in the long run can lead to immune hypofunction and amplified inflammatory responses. This systemic imbalance weakens the immune surveillance of the bronchi and triggers a hypersensitivity reaction to external stimuli, further aggravating mucus hypersecretion. For example, gastroesophageal reflux caused by digestive system problems frequently induces chronic cough and phlegm, demonstrating that the respiratory system and digestive system influence each other through the autonomic nervous system and immune system. Therefore, managing sticky phlegm requires an integrated approach that goes beyond merely resolving phlegm, aiming to balance whole-body immunity including the lungs, improve the inflammatory environment, and stabilize the autonomic nervous system.