Infants and young children have poor defenses and immature lung development, so the incidence is highest within 2 years of age, mostly secondary to upper respiratory tract infections and acute infectious diseases, and is most common in winter and spring. What are the causes of chronic cough, sputum and wheezing in winter and spring? 1. viruses: viral bronchopneumonia caused by canine distemper virus, canine adenovirus types I and II, canine parainfluenza virus, herpes virus, eutherian virus, and feline upper respiratory syndrome virus; 2. bacteria: Chlamydia psittaci. Bacterial bronchopneumonia caused by Mycobacterium tuberculosis, Pasteurella, Streptococcus, Staphylococcus, Escherichia coli, Nocardia, Actinomyces, Bordetella bronchiseptica, Klebsiella, etc.; 3. Fungi: fungal bronchitis caused by Cryptococcus, Histoplasma, Aspergillus, Candida, etc.; 4. Parasites: parasitic bronchitis caused by Trichinella aerophila, Toxoplasma gondii, Feline roundworm, Ascaris and Hookworm larvae, etc. 5. foreign bodies: foreign body pneumonia or allergic bronchitis caused by vomit, inhalation of irritants or certain allergic reactions; 6. some septic diseases: such as uterine infections and mastitis, whose germs can enter the lungs via the bloodstream and cause disease. Chinese medicine believes that cough is mostly caused by lung heat, especially in children. In daily diet, eating more fatty, sweet and thick flavors can produce internal heat and aggravate the cough, and the phlegm is sticky and not easy to cough out. For children with asthma, excessive consumption of sweet and fatty foods can cause heat and phlegm to build up in each other, blocking the respiratory tract and aggravating asthma, making it difficult for the disease to heal. Do not eat too much fried food. When children have a cough, their gastrointestinal function is weak, so fried food can add to their gastrointestinal burden and help with moisture and heat, producing phlegm and making the cough difficult to heal.