What is an exogenous cough?

The causes of coughs can be broadly categorized into two types: external pathogens and internal imbalances. Coughs caused by external pathogens result from the body being affected by external pathogenic factors; modern medicine believes these are related to viruses, bacteria, physical irritants, chemical fumes, parasitic diseases, and allergic reactions to foreign proteins. Triggering factors include exposure to cold, getting caught in the rain, excessive fatigue, and weakened constitutions in the elderly and young children. Coughs caused by internal imbalances result from disharmony among the internal organs.

In winter, many people are exposed to external pathogens; when these pathogens invade the lungs and cause coughing, it is referred to as an “exogenous cough.” Acute bronchitis generally falls within the scope of coughs as defined by Traditional Chinese Medicine.

The lungs are delicate organs located in the chest. They connect upward to the respiratory tract, open to the nose, and correspond externally to the skin and hair. As the primary organs governing the entry, exit, ascent, and descent of qi, the lungs can be affected by external pathogens whether they enter through the mouth and nose or are absorbed through the skin and hair. When lung qi fails to circulate properly and the functions of clearing and descending are disrupted, coughing may result. There are numerous patterns of coughs caused by external pathogens, but coughs due to wind-cold, wind-heat, and dry-heat are the most common. Treatment methods vary depending on the specific presentation.

1. Wind-Cold Cough: Patients present with thin, white phlegm, nasal congestion, clear nasal discharge, and an itchy throat, accompanied by symptoms such as a heavy, throbbing headache, chills and fever, absence of sweating, and body aches. Treating with San’ao Decoction, modified according to the specific symptoms, yields good results.
2. Wind-Heat Cough: Patients present with a cough producing yellow phlegm, difficulty coughing up phlegm, thirst, sore throat, hoarseness, yellow nasal discharge, fever with profuse sweating, aversion to wind, or symptoms such as headache and a sensation of fullness in the head. The tongue coating is thin and yellow, and the pulse is floating and rapid. Treatment should focus on dispelling wind, clearing heat, and promoting the free flow of lung qi. The Sangju Decoction, modified according to the specific symptoms, is recommended.
3. Dry-Heat Cough: Patients present with a dry cough without phlegm, or with scant, viscous phlegm that is difficult to expel; a dry nose and throat; severe coughing that may be accompanied by chest pain; or chills and fever, with streaks of blood in the phlegm. The tip of the tongue is red, the tongue coating is thin and yellow, and the pulse is fine and slightly rapid. Treatment should focus on clearing lung heat and moistening dryness. The Mulberry and Apricot Decoction, modified according to the specific symptoms, can be used to treat this condition.

Although exogenous coughs are caused by wind, cold, or heat and have an acute onset, they are easily cured in the early stages. However, if the condition persists or is complicated by dampness or dryness, active and thorough treatment is required; otherwise, it may recur or lead to chronic bronchitis, cor pulmonale, or asthmatic bronchitis.

Prevention of exogenous cough: Take care to avoid exposure to cold, getting caught in the rain, and excessive fatigue. Engage in regular exercise to strengthen the body’s defenses. If you develop an exogenous cough, seek treatment early and ensure a complete cure. During medication, get plenty of rest, stay warm, and abstain from smoking and alcohol; this will promote a faster recovery and help prevent complications.