Coughing up phlegm at night may be caused by chronic pharyngitis, colds, allergic coughs, cough variant asthma and so on, which can be treated under the guidance of the doctor by taking relevant medications. 1. Chronic pharyngitis: coughing up phlegm at night may be caused by chronic pharyngitis, which is mainly associated with nasopharyngeal diseases, bad habits, occupational factors, etc., you can use furacilin solution, compound borax solution, compound chlorhexidine gargle solution and other gargles. 2. Colds: Colds are caused by viral infections, viral infections of the throat, resulting in pharyngeal congestion, edema, oozing may lead to coughing at night, coughing up phlegm symptoms. If the symptoms are mild, no medication can be taken. If the cough symptoms are more severe, cough and phlegm medication such as bromhexine, aminoglutethimide hydrochloride and compound ammonium chloride can be given for treatment. 3. Allergic cough: The cough is mainly caused by the inflammatory reaction of airway caused by contact with allergens such as dust, willow, pollen and other substances. It can be treated by taking anti-allergic drugs such as loratadine and cetirizine. 4. Cough variant asthma: If the patient coughs up sputum at night, it may be caused by cough variant asthma, mainly related to genetic factors, environmental factors, etc., can be treated with glucocorticoids, commonly used drugs such as budesonide powder inhaler. There are many other diseases that cause coughing up clear phlegm at night, such as heart failure and gastroesophageal reflux disease. If the patient’s symptoms continue to be bad or aggravated, it is recommended that the patient go to the hospital in a timely manner to improve the examination, a clear diagnosis, and strictly comply with the doctor’s instructions to use medication, not blindly use drugs or stop taking medication without authorization, so as to avoid aggravation of the condition.