Dextromethorphan Guaifenesin Syrup has the effect of relieving cough and resolving phlegm, and is very effective for cough and phlegm caused by common cold or influenza, as well as upper respiratory tract infection and bronchitis. It is an over-the-counter medicine to suppress cough and expectorant. Generally adults take 10-20ml once, 3 times a day, no more than 4 times in 24 hours. Adverse reactions generally include dizziness, headache, lack of appetite, constipation, skin allergy and other symptoms, which will disappear after stopping the medication. It is recommended to consult a hospital if the symptoms are not relieved after 7 days of medication.