Phlegm and rumbling in the airways may be caused by allergic bronchitis, acute bronchitis, asthma and so on. The cause of the disease is different, the treatment method is different, and what kind of medicine to take is also different. 1. Allergic bronchitis caused by phlegm in the airways and croup because of allergies leading to bronchial mucosal congestion and edema, antiallergic drugs such as ketotifen, montelukast, loratadine, etc., in addition to the use of cotrimoxazole, with an antiallergic, antitussive and antispasmodic effect. 2. Acute bronchiolitis is most common in young children under 1 year old, given oxygen therapy and anti-inflammatory treatment. Anti-inflammatory treatment is mainly inhaled glucocorticoids such as budesonide inhaler. 3. Asthma causes phlegm and rales in the airways. Short-acting beta 2 agonists such as salbutamol are given immediately for acute attacks. Long-term control is mainly by inhaled glucocorticoids such as budesonide and fluticasone, combined with long-acting β2-agonists such as formoterol. Antibiotics such as ceftriaxone and levofloxacin may be given in case of co-infection. If there is phlegm in the airway and croup, consult a respiratory physician to determine the cause of the problem. The above medications should be used in a standardized and rational manner under the guidance of a professional physician and pharmacist.