A randomized, double-blind, placebo-controlled clinical trial of Shen Mi Tang in Treating subacute cough

INTERVENTION: The study will be a randomized, placebo‐controlled, double‐blind clinical trial with medication for 7 days followed by observation for 7 days also. There were two groups in the study. The subjects of Treatment group will take Shen Mi Tang (400mg), 5 capsules three times a day(6g per day) per oral for a 7 days course of treatment. Components of Shen Mi Tang Ephedrae Herba 6g Armeniacae Semen 4.8g Magnoliae Cortex 3.6g Auranti Nobilis Pericarpium 3g Glycyrrhizae Radix 2.4g Bupleuri Radix 2.4g Perilla Herba 1.8g These raw herbs were refined to 4g extract and mixed with 2g starch to 6g powder by Sheng Chang Pharmaceutical Co., Ltd. dextromethorphan 15mg/TAB per oral one to three times a day will be given as rescue drug when cough is intolerable To get cough symptom score , a phone call at day 3,5 of treatment was given to the patients by study coordinator. a card was also given to patient to record their daily drug taking and Visual Analogue Scale(VAS) of cough. The Visual Analogue Scale(VAS) will be adopted for measuring the severity of patient reported cough.The patient will be asked to mark the severity of his/her cough condition on a visual analogous scale of 0 to 100 mm at the time points (Day 1,3,5,8,15). CONDITION: post infectious cough PRIMARY OUTCOME: Percentage of patients with "Significant Improvement" in daytime Cough Symptom Score(CSS) will be the primary efficacy endpoint of this study. ; SECONDARY OUTCOME: Change from baseline in visual analogous scale(VAS) score on cough severity Percentage of patients with ’’Improvement” in daytime or night‐time Cough Symptom Score(CSS) ; INCLUSION CRITERIA: 1.age from 20 to 65 y/o 2.persist cough for 3‐8 weeks without present illness as asthma, Gastroesophageal reflux disease,postnasal drip) 3.Cough pattern is dry cough or cough with little sputum. presentations of cough are throat itching, paroxysmal cough or cough irritated by smoke,dust or temperature. 4.Day time or night‐time Cough Symptom Score (CSS) >= 2 5.sign informed consent form