Phlegm in the left bronchus may be caused by pneumonia, chronic obstructive pulmonary disease, bronchial asthma and other diseases. It can be relieved by physical therapy and medication. 1. Physiotherapy: For patients with phlegm in the left bronchial tube, you can take the right lying position, ask their family members to evenly pat the patient’s back, and at the same time, encourage the patient to cough, and through coughing the phlegm in the left bronchial tube will be discharged. 2. Medication (1) If the phlegm in the left bronchus is caused by pneumonia or chronic obstructive pulmonary disease, some expectorants such as Ambroxol and Bromhexine can be used to promote the expulsion of phlegm; drugs such as acetylcysteine can be inhaled to dilute the phlegm; at the same time, some antibiotics such as Piperacillin Sulbactam and Levofloxacin are also needed for anti-infective treatment. (2) If the phlegm in the left bronchial tube is caused by bronchial asthma, it is necessary to keep away from allergens, and inhaled hormones such as budesonide, some anti-allergic drugs such as montelukast sodium and expectorants such as aminoglutethimide can be used to alleviate the above symptoms. 3. Other treatments: Due to the anatomical structure of the left bronchus is thin and long, sputum is not easy to be discharged. If the above methods are ineffective, the sputum can also be expelled by mechanical shock, bronchoscopy for suction treatment, etc., so as to completely suck out the sputum. For patients with phlegm in the left bronchus, they should actively consult a doctor and complete relevant examinations such as sputum culture + drug sensitivity test and lung CT to clarify the cause of the disease. The drugs mentioned above should be taken under the guidance of professional doctors.