As the winter and spring seasons change again, the number of patients in the respiratory clinic begins to increase, and many of these patients come to the hospital suffering from recurrent cough. First of all, is cough a disease? In fact, cough is a symptom of many diseases, including respiratory diseases and diseases of other systems. It is in fact a reflex mechanism of the body to protect the respiratory tract and to help clear respiratory secretions. It is a physiological reflex caused by an impulse to the coughing center after the respiratory tract has been stimulated, which discharges respiratory secretions or foreign bodies and protects the cleanliness and smoothness of the respiratory tract, making it a useful reflex action and a necessary protective reflex for healthy humans. Under normal circumstances, a mild and infrequent cough can be relieved naturally by expelling sputum or foreign bodies. However, in the case of frequent and violent coughing, it can cause distress, interfere with rest and sleep, increase physical exertion, and have a serious impact on work and life. We often meet patients in outpatient clinics who have been coughing for a long time and do not think it is a serious problem at first. They go to the pharmacy and buy all kinds of cough drops and anti-inflammatory drugs that they can take at home, but their cough seems to get better and then it doesn’t. They go back and forth. Sometimes, I also used local remedies, such as stewed radish juice with loquat leaves, boiled eggs with honey, and various other things, but it just wouldn’t go away. When the coughing becomes unbearable, sometimes the family is overwhelmed by the coughing, so they will think of coming to the clinic. This is something we often encounter in outpatient clinics. Therefore, the question of how to treat coughs, whether they all need saline and whether they all need antibiotics, requires further clarification of the diagnosis and rational treatment based on various causes. Let’s start by classifying coughs into categories. Usually, we classify coughs into 3 categories according to time: acute cough, subacute cough and chronic cough. Acute cough lasts <3 weeks, subacute cough is 3 to 8 weeks, and chronic cough is >8 weeks. Chronic cough has many causes and can be divided into two categories according to the presence or absence of abnormalities in chest X-ray examinations: those with clear lesions on X-ray chest films, such as pneumonia, tuberculosis, lung cancer, etc.; and those with no obvious abnormalities on X-ray chest films and cough as the main or only symptom, which is the common unexplained chronic cough (referred to as chronic cough) in clinical practice. When a patient comes to the clinic to see a cough, the doctor will usually first ask about some medical history surrounding the cough. Depending on how long the cough lasts, the diagnosis can be narrowed down to acute, subacute or chronic cough. The etiology of acute cough is relatively simple, with the common cold and acute tracheobronchitis being the most common diseases for acute cough. The clinical manifestations of the common cold are nasal-related symptoms, such as runny nose, sneezing, nasal congestion and postnasal drip flu, throat irritation or discomfort with or without fever. The cough of the common cold is often associated with postnasal drip and irritation in the throat. Treatment is generally symptomatic and in many cases does not require the use of antibacterial drugs. Drugs containing pseudoephedrine hydrochloride and other drugs that reduce the effect of mucosal congestion and antihistamines that reduce glandular secretion can be used. Clinically, a combination of the above drugs is usually used, and first-generation antihistamines + pseudoephedrine are preferred for treatment, which can help relieve sneezing, nasal congestion and other symptoms. For example: Tylenol, Neocontrol, etc. If the cough is more severe, you can also use some drugs that clear heat and stop coughing and dissolve phlegm, and cough suppressants can also be used. Acute tracheobronchitis is an acute inflammation of the tracheobronchial mucosa caused by various factors. Viral infections are the most common cause and can be followed by bacterial infections. Cold air, dust and irritating gases can also cause or aggravate the disease. In the past two days, the weather has changed to cold and the air quality may not be good, so there has been a surge in respiratory coughs, many of which are due to acute tracheobronchitis. The clinical manifestations often start with symptoms of upper respiratory tract infection. Subsequently, the cough may increase gradually, with or without coughing up sputum, and with bacterial infections, often with yellow pus sputum. The cough and sputum usually last for 2 to 3 weeks, but there is no significant abnormality on X-ray or only increased lung texture. On examination, the breath sounds in both lungs are coarse, and sometimes wet or dry woven sunglasses can be heard. If there is a bacterial infection, such as purulent sputum or an increase in peripheral blood leukocytes, some antibacterial drugs may be appropriate. If there is bronchospasm, bronchodilator drugs can be used to treat it. Another point to note is to quit smoking. We often encounter patients who come to the clinic with a cough, but a strong smell of cigarette smoke comes out of their mouth. In people who smoke, bronchial mucosal defenses and repair capabilities are weakened, which is more pronounced in acute airway inflammation and can make the cough more severe. The most common cause of subacute cough is post-infection cough. When the symptoms of the acute phase of a respiratory infection have disappeared, the cough remains prolonged. In addition to respiratory viruses, other pathogens such as bacteria, mycoplasma and chlamydia can cause a post-infectious cough, with coughs caused by colds being the most common, also known as “post-cold cough”. This type of cough is usually characterized by an irritating dry cough or a small amount of white mucus sputum and usually lasts 3 to 8 weeks, with no abnormalities on x-ray chest examination. When dealing with this condition, it is important to first determine whether the cough is secondary to the original respiratory cold symptoms and to treat it empirically. If treatment is ineffective, other etiologies are considered and the diagnostic procedure for chronic cough is consulted. Post-infectious cough is self-limiting and mostly resolves on its own. Antibiotics are usually not necessary, but treatment with macrolide antibiotics is effective for post-infectious cough caused by Mycoplasma pneumoniae and Chlamydia. For some patients with significant cough symptoms, short-term applications of cough suppressants and antihistamines plus decongestants can be used. The common causes of chronic cough include cough variant asthma (CVA), upper airway cough syndrome, eosinophilic bronchitis and gastro-oesophageal reflux cough, which account for 70% to 95% of the causes of chronic cough in respiratory medicine outpatient clinics. Most chronic coughs are not associated with infection and do not require treatment with antibacterial drugs. Cough variant asthma is a specific type of asthma without obvious symptoms such as chest tightness, wheezing and shortness of breath, and cough is its only or main clinical manifestation. It is mostly an irritating dry cough, usually more intense, and nocturnal cough is an important feature. Cold, cold air, dust, fumes, and various allergens can easily induce or aggravate coughing. Last month I saw a patient in the outpatient clinic who had been coughing for more than 3 months with a very violent cough, especially at night. She had used many antibiotics and various cough suppressants elsewhere, but they were not effective. I took a chest X-ray, but there was nothing wrong with it. After a routine blood test, I found that her eosinophils were a bit high, suggesting that her cough was allergy-related. So I proceeded to ask out and it turned out that she had recently gotten a pet dog that she just happened to have for over 3 months as well. I did another pulmonary function on her and confirmed that there was a small airway obstruction. At my suggestion she gave the pet dog away and I gave her inhaled hormones and a bronchodilator and a leukotriene receptor antagonist, cisplatin, at bedtime, which worked very well and after a week the cough cleared up significantly. Upper airway cough syndrome, which used to be called postnasal drip syndrome, is a very imaginative name for a syndrome in which nasal disease causes secretions to flow backwards behind the nose and throat and other areas, directly or indirectly stimulating cough receptors, resulting in a cough as the main manifestation. In addition to nasal diseases, UACS is often associated with diseases of the throat, such as acute pharyngitis, laryngitis, pharyngeal neoplasia, and chronic tonsillitis. In addition to cough, it also presents with nasal congestion, increased nasal discharge, frequent throat clearing, adherence of mucus in the back of the throat, and postnasal drip of influenza. It can be accompanied by nasal itching, sneezing, increased nasal discharge, throat itching, sore throat, foreign body sensation or burning sensation in the throat. Sometimes there can also be hoarseness. In laryngoscopy, some patients may have pebble-like changes in the mucosa of the oropharynx or mucopurulent secretions in the posterior pharyngeal wall. CT of the nasopharynx may show thickening of the mucous membrane of the sinuses and the presence of fluid planes in the sinuses. First-generation antihistamines (e.g., ketotifen and paracetamol) and decongestants are preferred for treatment. In the case of concomitant bacterial sinusitis, which leaves yellow pus nasal discharge, antibiotics are required as appropriate. Eosinophilic bronchitis is a non-asthmatic bronchitis characterized by airway eosinophil infiltration, mainly presenting as a chronic cough that responds well to glucocorticoid therapy. It also manifests clinically as a chronic irritant cough, often the only clinical symptom, with a dry cough or a little white mucus sputum, either during the day or at night. The main difference from CVA is normal pulmonary ventilation without evidence of airway hyperresponsiveness. Diagnosis relies primarily on induced sputum cytology with an eosinophil ratio of ≥2.5%. Treatment with short-term oral or inhaled glucocorticoids is very effective. Gastro-oesophageal reflux cough is a specific type of GERD and a common cause of chronic cough due to reflux of gastric acid and other gastric contents into the esophagus, resulting in a clinical syndrome with cough as the prominent manifestation. Typical reflux symptoms are heartburn (burning sensation behind the sternum), acid reflux, belching, etc. Some GERD-induced coughs are accompanied by typical reflux symptoms, but many patients have cough as the only manifestation. The cough mostly occurs during the day and in the upright position, with a dry cough or a small amount of white mucous sputum. The cough is easily triggered or aggravated by the consumption of acidic and oily foods. The diagnosis relies on 24h esophageal pH test in addition to clinical symptoms. However, this test is rarely available in hospitals. Therefore, for cough with obvious feeding-related symptoms of reflux, accompanied by typical symptoms of heartburn and acid reflux, and when other treatments are not effective, try taking some medications that inhibit stomach acid (e.g. omeprazole 20mg twice daily), which often work. In addition to these main causes of coughing just mentioned, there are some other conditions to pay attention to. For example, hypertensive patients taking angiotensin-converting enzyme inhibitor antihypertensive drugs such as Mono and Lortinexin are also common causes of chronic cough. Cough is a common adverse effect of these antihypertensive drugs, with an incidence of 10-30%, and the cough will gradually improve after stopping the drug and changing to other antihypertensive drugs. It is also important to note that many of the cough conditions we are talking about today are based on the absence of abnormalities in the chest X-ray. If a chest X-ray reveals problems such as pneumonia, tuberculosis, bronchiectasis, etc., there will be other appropriate treatment. Moreover, chest radiographs sometimes have their limitations and cannot reflect the subtle lesions of the lungs very comprehensively. Therefore, for patients with a long history of smoking, symptoms such as irritating dry cough, blood in sputum, chest pain, wasting, or changes in the nature of the original cough, a further lung CT is needed to rule out the possibility of lung cancer. We once met a patient who also had a cough that was not good all the time. He had seen the cough in several hospitals and followed the regular treatment plan for a long time with no effect. When he came to our clinic, a doctor with lower seniority saw that he had been coughing for a long time and had not had a lung CT, so he was prescribed a CT test and the result was an early stage central lung cancer. If you are suffering from cough, don’t use antibiotics blindly, it is better to quit smoking and avoid spicy and irritating food, and go to a regular hospital for examination and treatment.