In the respiratory outpatient clinic, patients often ask: "Doctor, I have been coughing for a long time, and I have not recovered from anti-inflammatory drugs and cough medicines, what should I do?" ”
Chronic cough is defined as a cough that lasts more than 8 weeks and shows no obvious abnormalities on chest imaging. Most chronic coughs are not related to infection, and the main symptom of patients is a prolonged cough that does not heal, and various antibiotics and cough suppressants are used for a long time, but with little effect. Chronic cough may seem to have similar symptoms, but there are many causes, and the premise of effective cough suppressant is to identify the cause of chronic cough. Let's take a look at these different causes of chronic cough.
Cough variant asthma
Cough variant asthma (CVA) refers to a special type of asthma with chronic cough as the main or only clinical manifestation, without obvious wheezing, shortness of breath, etc., but with airway hyperresponsiveness. CVA is the most common cause of chronic cough in adults in mainland China, accounting for about 1/3 of all causes.
The cough caused by CVA is usually more violent, manifested as irritating dry cough, and the cough is more pronounced at night, more often than during the change of seasons (especially in spring and autumn), weather changes, exercise, inhalation of cold air/oil smoke/dust mites/animal dander, etc. Patients often have an allergic disease or family history, and about 60% of patients have a positive skin prick test for allergens.
If CVA treatment is not timely or standardized, it may develop into typical bronchial asthma. In most patients, regular inhalation of low-dose glucocorticoids plus β receptor agonists is effective in improving cough symptoms, and treatment should be no less than 8 weeks. If it is clear that the spring and autumn seasons are approaching or the weather is getting colder, patients with recurrent symptoms can be treated in advance to prevent cough attacks. Patients who are allergic to dust mites/animal dander need to be detached from the allergen.
Upper airway cough syndrome
Upper airway cough syndrome (UACS), also known as postnasal drip syndrome (PNDS), is an umbrella term for various nasopharyngeal disorders that lead to cough. This syndrome is a cough caused by nasal diseases causing secretions to flow backwards into the back of the nose, throat, etc., and stimulating cough receptors. The underlying diseases of UACS are mainly allergic rhinitis and sinusitis.
The cough of UACS is mostly accompanied by sputum production, mainly during the day, and there is rarely cough after falling asleep, often accompanied by postnasal drip flu, itchy throat, nasal congestion, sneezing, runny nose, etc., and the patient often clears his throat, and sometimes his voice is hoarse. Physical examination reveals hypertrophy and hyperemia of the nasal mucosa, cobblestone changes in the oropharyngeal mucosa, and mucus discharge from the posterior pharyngeal wall.
The choice of treatment for UACS depends in part on the underlying disease. For allergic rhinitis, nasal inhaled corticosteroids (e.g., beclomethasone propionate) and oral second-generation antihistamines (e.g., loratadine) are preferred. Treatment of bacterial sinusitis includes antibiotics (usually amoxicillin or cephalosporins), intranasal hormones, and decongestant drugs. If the medical treatment of the disease is inadequate, nasal endoscopic surgery may be considered.
Gastroesophageal reflux cough
Gastroesophageal reflux cough (GERC) refers to the reflux of gastric acid and other gastric/duodenal contents into the esophagus tubes, resulting in a clinical syndrome with cough as the main manifestation, and is a specific type of gastroesophageal reflux disease (GERD). GERC is mostly irritating dry cough, mostly occurring during the day and in the upright position, and eating acidic and greasy foods can easily induce cough, often accompanied by heartburn (retrosternal burning sensation), acid reflux, belching, etc. 24-hour esophageal pH monitoring can help diagnose the condition.
The treatment of the disease is mainly based on dietary modifications, such as low-fat diet, eating small, frequent meals, avoiding food before bedtime, and reducing coffee/chocolate intake. If symptoms are evident in the supine position, the head of the bed can be elevated to reduce regurgitation while sleeping. Inhibition of gastric acid secretion is an important treatment, and proton pump inhibitors (omeprazole, rabeprazole, etc.) are preferred, and H2 receptor antagonists (famotidine, ranitidine, etc.) can also be used. When symptoms are severe, both drugs may be used. When the effect of antacids alone is not good, gastrointestinal motility drugs (domperidone, mosapride) can be added. Surgery may be considered when medical treatment is ineffective.
Eosinophilic bronchitis
Eosinophilic bronchitis (EB) is a type of bronchitis characterized by an eosinophilic infiltrate of the airways with normal lung ventilation and no evidence of airway hyperresponsiveness that precludes the diagnosis of bronchial asthma. The main symptom of EB is a chronic irritating cough, which is generally dry and predominantly during the day. Some patients are sensitive to fumes, dust, odors, or cold air, and the cough may disappear quickly or be significantly reduced after treatment with glucocorticoids (inhaled budesonide for more than 8 weeks).
Cough after infection
Post-infection cough (PIC) refers to the patient's cough that persists after the symptoms of the acute phase of respiratory infection disappear, among which the cough caused by viral influenza is the most common, also known as post-cold cough. PIC resolves on its own, and if it is an occasional cough, no medication is required. If cough symptoms are significant, a short-term use of antitussive drugs is recommended. If there is a lot of phlegm, oral expectorants, such as ambroxol, can be taken orally.
Drug-induced cough
Some medications can also cause coughing in the person taking them. For example, the common adverse reaction of taking angiotensin-converting enzyme inhibitor (ACE inhibitor) antihypertensive drugs (such as captopril, benazepril, enalapril, perindopril, etc.) is cough, with an incidence of 10%~30%. Cough usually disappears or is significantly reduced after 4 weeks of discontinuation of ACE inhibitors. Patients with hypertension who have cough can switch ACE inhibitors to angiotensin II receptor antagonists (eg, losartan, valsartan, etc.).
Psychogenic cough
Psychological cough, also known as "habitual cough" and "psychogenic cough", is relatively common in children and is caused by psychological problems or intentional throat clearing. It typically presents with a usual cough, but the cough disappears when focused on a certain event and during night rest, and may be accompanied by anxiety and other undesirable emotions when the cough attacks. Suggestion therapy, counseling, and anti-anxiety or antidepressant drugs may be effective for psychogenic cough.
In addition to the above, there are several other causes of chronic cough such as interstitial lung disease, bronchial foreign body, left ventricular insufficiency, mediastinal tumors, etc.
To sum up, the causes of chronic cough are complex, and it is necessary to further clarify the cause according to the clinical manifestations and related examinations, and then "treat the cause" in order to "cure the disease". Therefore, patients with long-term cough are advised not to use drugs indiscriminately and to visit a respiratory clinic as soon as possible.
Text: Yang Liu, Department of Respiratory and Critical Care Medicine, Beijing You'an Hospital, Capital Medical University
Editor: Mu Xinyu Guan Zhongyao
Proofreading: Ma Yang
Review: Qin Mingrui, Xu Bingnan
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