1. Respiratory infections and post-infection cough Respiratory infections are the most common reason for children to seek medical attention for cough: 3.8 to 5 respiratory infections accompanied by cough in children under 5 years of age per year; 10% of school-age children and 20% of preschoolers visit the doctor for cough; the average coughing time after respiratory infections is 1 to 3 weeks, but 10% of coughs will last longer than 4 weeks; 37.6% of children with respiratory infections have viral co Mycoplasma pneumoniae and Chlamydia pneumoniae infections. About 53% of coughs are caused by multiple factors. Respiratory infections caused by many pathogenic microorganisms such as Mycobacterium pertussis, Mycobacterium tuberculosis, viruses (especially respiratory syncytial virus, parainfluenza virus, cytomegalovirus), Mycoplasma pneumoniae, and Chlamydia are common causes of chronic cough in children. It is mainly due to increased sensitivity of cough receptors and is usually insensitive to b agonist and inhaled hormone therapy. It is mostly seen at 4 weeks, often attacks or worsens at night and/or early in the morning, with a predominantly dry cough; treatment of cough variant asthma: experimental treatment with b agonists and inhaled glucocorticoids, with efficacy assessed at 2-4 weeks of treatment and reassessment with discontinuation of ineffectiveness; duration of treatment is not less than 6-8 weeks. 2. Upper airway cough syndrome (UACS) The causes are mainly infections, allergic rhinitis, sinusitis, etc. Rhinitis/sinusitis is not uncommon in older children and often presents with itchy, painful throat, cough, mucopurulent sputum, and in some children, a feeling of flowing secretions in the throat; on examination, the lymphatic follicles in the pharynx are hyperplastic and may appear cobblestone-like. Cough is a symptom of sinusitis, but persistent or recurrent cough is rarely the only clinical symptom in children, and sinus x-ray is not routinely recommended for preschoolers. Treatment of UACS: First-generation antihistamines (excluding finasteride) and pseudoephedrine are generally recommended. The new generation non-sedating antihistamines are less effective because of their weaker anticholinergic effect. Nasal hormones and decongestants can also be used. Nasal ipratropium bromide can be tried. Gastroesophageal reflux and cough in children According to the American College of Chest Physicians, gastroesophageal reflux is one of the three leading causes of chronic cough, but it is based on expert opinion and a limited number of uncontrolled studies, and the prevalence varies widely by region. Gastroesophageal reflux with aspiration has been suggested in the literature as a causative factor. In infancy, reflux is common and the clinical course is self-limiting and usually not accompanied by cough. The occurrence of reflux in healthy children is uncommon, and in China it has been reported that primary gastroesophageal reflux causes only 2% of coughs in children with persistent coughs for more than 4 weeks. In childhood, reflux is mainly seen in those with hypomodulation and hypotonia of the medulla oblongata, where patients develop primary or secondary aspiration-related cough due to gastroesophageal reflux; therefore, routine investigation and treatment of gastroesophageal reflux is not necessary in most children with cough. The cough due to gastroesophageal reflux is usually: paroxysmal, sometimes violent, and occurs mostly at night. The symptoms mostly appear after eating and drinking and feeding is difficult. Some children have upper abdominal or subxiphoid discomfort, burning sensation behind the sternum, chest pain, and sore throat. In addition to causing coughing, infants may suffer from asphyxia, bradycardia and an arched back. It may lead to stagnant or delayed growth of the affected child. 4. Psychogenic cough It is more common in children and adolescents. It is characterized by the absence of coughing after sleep, often with symptoms of anxiety. The characteristic goose-call-like cough or barking cough in children helps in the diagnosis and is not uncommon clinically. Cough characteristics are only suggestive, not diagnostic, and exclusionary diagnosis is used. 5. Tic disorder in children (TIC) and cough Nowadays, the use of stimulants to control attention deficit disorder in children is increasing and many patients are prone to tic disorder. Among these stimulants (e.g., Ritalin) are thought to exacerbate or induce the onset of tics, which can manifest as a nonspecific dry cough in children. 6. Foreign body aspiration in children Foreign body aspiration can occur in children. About 50% of children have no witnesses at the time of foreign body aspiration, and 20% of children are seen more than 1 week after foreign body aspiration. Therefore, foreign body aspiration should be ruled out in every child with persistent cough of unknown origin, as failure to remove foreign bodies in a timely manner can lead to permanent airway damage. If the history includes a history of transient breath-holding respiratory distress, wheezing or coughing, even if the X-ray chest radiograph is normal, foreign body aspiration should be suspected and bronchoscopy should be considered. Children with foreign body aspiration usually start with an irritating dry cough, which turns into sputum if an infection of the lungs develops. A breath-phase x-ray of the chest can help improve the diagnosis of foreign body aspiration in children. Those with abnormal medulla oblongata function can have recurrent pulmonary aspiration due to primary or secondary gastroesophageal reflux, cough due to irritation of the larynx by the foreign body, or cough due to the collection of inhaled material in the lungs, with most clinical manifestations being an irritating dry cough. 7. Congenital respiratory diseases Mainly seen in infants. Multiple causes lead to chronic cough. For example, laryngotracheobronchial softening and stenosis; vascular ring compression; tracheoesophageal fistula aspiration; cilia motility disorders.