Coughing is one of the most common symptoms in children, and many children have long coughs or recurring coughs that bother many parents. Today I’m going to teach you simple methods and knowledge to determine the cause of a cough, and you’ll get something out of it if you read it carefully! From a professional point of view in layman’s terms, a child’s cough of more than 4 weeks is called chronic cough, excluding bronchial foreign bodies such as choking on melons and peanuts in the airway, and excluding idiosyncratic coughs such as airway and lung pathologies themselves, such as tracheobronchial malformations and sequelae of severe pneumonia, etc. What remains is several non-specific coughs such as upper airway cough syndrome, cough variant asthma, and post-infection cough. The eight main points are summarized as follows: 1. Judging from age: coughs in babies under 1 year old are nothing but infections and respiratory deformities, infections such as bronchitis and pneumonia, and respiratory deformities such as laryngeal-tracheal cartilage softening and airway narrowing. 2. Dry cough and wet cough (cough with phlegm or cough with phlegm sound): dry cough is usually more non-infectious cough, such as cough caused by allergic rhinitis, cough variant asthma, and post-infectious cough. 3. Upper airway cough syndrome (postnasal drip syndrome): this is easy to determine, just from the name of the disease. Simply put, it is a cough related to the nose, and children with allergic rhinitis or sinusitis belong to this category. In children with allergic rhinitis or sinusitis, the cough is caused by the backward flow of nasal snot that stimulates the throat. It is characterized by the child’s tendency to rub his nose, suck in nasal snot, clear his throat because he is uncomfortable, and cough more in the morning. 4. Post-infection cough and cough variant asthma: Some children have a cough that lasts for a long time after a cold and fever, called post-infection cough, while asthma that only coughs without shortness of breath is cough variant asthma. It is not easy to distinguish between these two diseases. Many children with post-infectious cough also have a morning and evening cough and an increased cough after exercise, such as cough variant asthma, and infections can also trigger cough variant asthma attacks, making the two diseases confusing to many non-specialists. We just need to remember two things: (1) coughing for more than 8 weeks is often not a post-infection cough, unless the child is almost done with the infection and has a new cough course due to a cold and fever; (2) cough variant asthma is the one with good nebulizing effect, which is one of the basic features of asthma with airway reversibility. 5, bronchial foreign body: can occur in infants and toddlers to adolescents of all ages, if the child originally did not cough, suddenly once eating especially solid food such as melon, peanuts, beans because of crying and quarrelling or laughing and other reasons suddenly choke cough, after that the cough is always bad. Some children’s parents are not around, so the child will not say anything after choking on something, and in some cases of bronchial foreign bodies, the cough has a “silent period”, and the cough only worsens after a few days, which is often easy to ignore. If the cough does not look like other causes or if the treatment is not effective, a high-resolution CT of the lungs is needed for diagnosis. 6, the sequelae of severe pneumonia (occlusive bronchitis): if the child has had a very serious pneumonia caused by, for example, adenovirus, measles virus, mycoplasma, etc., a large lesion in the photo or even on a ventilator, then we should be careful, if the hospitalization symptoms are better, the lung photos still have obvious lesions, coughing is always bad, or a cold is difficult to breathe, often this type of lesion. 7. The most common cough diseases for chronic cough are cough variant asthma, upper airway cough syndrome, and post-infectious cough in order of patient number, accounting for almost 90% or so of chronic coughs, so we should start considering the most common diseases in our judgment thinking. 8. Finally, I would like to tell you that upper airway cough syndrome and cough variant asthma can coexist, and other cough diseases can also complicate bronchial foreign bodies. If the cause of the cough is still unknown or the treatment is not effective, a CT or even fiberoptic bronchoscopy of the lungs is needed.