A child with a low immune system is prone to dry cough, which is a sign of airway hyperresponsiveness, and although it is common, it needs to be taken seriously if it lasts for too long. Dry cough in children is commonly due to the following causes: 1. Respiratory infections. Respiratory infections, including bacterial, viral, mycoplasma, chlamydia or other microbial infections, can induce itchy throat, sore throat and stimulate the cough reflex in children, which can easily lead to a dry cough after a long period of time. This is often seen in pharyngitis and mycoplasma infections. A special note is the need to be alert to mycoplasma infections, and paroxysmal dry coughs can be tested with respiratory pathogenic spectrum tests, or pharyngeal test strips, or multimedia tests. Treatment requires symptomatic treatment such as anti-infection and cough suppression. 2.Dry cough stimulated by unfavorable environment. It is common in cold air, dry air, after running exercise, seasonal change, weather change to stimulate dry cough, for example, cold air stimulation can induce congestion and edema of respiratory mucosa, inflammation-like reaction and reflex cough. 3. Allergic reactions. Dry cough can occur as a result of allergic reactions. The most common are allergic cough, upper airway cough syndrome, and bronchial asthma. Special attention needs to be paid to allergic cough, which can manifest as a persistent recurrent dry cough, obvious in the early morning at night, aggravated after exercise, without clinical manifestations of infection, ineffective antibiotic treatment, and often with a personal or family history of allergy. 4. Bronchial foreign body. This can easily occur in children. Choking occurs during eating and drinking, and foreign bodies are retained in the bronchi, and a dry cough can occur. It is easy to combine bacterial and viral infections and develop into bronchitis/pneumonia and be detected. Pulmonary imaging or fiberoptic bronchoscopy can be performed to clarify. 5. Pleural diseases can also induce a dry cough. For example, pleurisy or compression of adjacent organs. When a child has a dry cough, it is important to avoid spicy foods in the diet, eat more fresh vegetables and fruits, drink more warm water, and actively consult the hospital to find the cause.