Chinese herbal tea to enhance stopping smoking

INTERVENTION: Experimental group: Chinese herbal tea combined with conventional therapy (based on physician prescription) for 4 weeks. Control group: conventional therapy (based on physician prescription) for 4 weeks. After 4‐week treatment, all participants can choose by their own will to receive which treatment for 8 weeks, we conduct the follow‐up for these 8 weeks. Participants are randomly allocated to groups using the sealed envelope method. CONDITION: Treatment for patients who are willing to stop smoking in smoking cessation clinic ; Not Applicable PRIMARY OUTCOME: ; 1. Carbon monoxide expiratory volume is measured using Carbon monoxide detector at baseline, 1day, 4 weeks.; 2. Abstinence rate is measured using patients’ self‐report at baseline, 1 day, 1 week, 2 weeks, 3 weeks, 4 weeks, 8 weeks, 12 weeks.; 3. Nicotine dependence is measured using Fagerstrom test for nicotine dependence (FTND) at baseline, 1 day, 1 week, 2 weeks, 3 weeks, 4 weeks, 8 weeks, 12 weeks.; 4. Implementation outcomes of combined Chinese herbal tea during smoking cessation treatment is measured using questionnaire and interview (containing acceptability, appropriateness, feasibility, adoption, fidelity, and sustainability) at baseline, 1 week, 2 weeks, 3 weeks, 4 weeks, 8 weeks, 12 weeks.; SECONDARY OUTCOME: ; 1. Nicotine withdrawal symptoms are measured using Minnesota Nicotine Withdrawal Scale (MNWS) at baseline, 1 day, 1 week, 2 weeks, 3 weeks, 4 weeks, 8 weeks, 12 weeks.; 2. Traditional Chinese medicine (TCM) syndrome is measured using TCM scale at baseline, 1 week, 4 weeks, 8 weeks, 12 weeks.; 3. Safety outcomes are measured using blood examination (ALT, AST, GGT, BUN, Cr, UA, biochemical electrolyte) at baseline and 4 weeks.; 4. Adverse events are measured using patients’ self‐report at 1 day, 1 week, 2 weeks, 3 weeks, 4 weeks, 8 weeks, 12 weeks during the whole course of study.; INCLUSION CRITERIA: 1. Patients in smoking cessation clinic seeking treatment. 2. Patients eligible for conventional medication. 3. The patients voluntarily sign the informed consent.