A randomized clinical trial of St. John's wort for smoking cessation.
What this study found
St. John’s wort did not improve smoking cessation or nicotine withdrawal compared with placebo. At 12 weeks, self-reported abstinence was 20.0% with 900 mg/day and 18.0% with 1800 mg/day versus 18.0% with placebo; biochemically confirmed abstinence was 20.0% and 15.4% versus 18.0%. At 24 weeks, biochemically confirmed abstinence was 17.5% with 900 mg/day and 18.0% with 1800 mg/day versus 10.3% with placebo, with no significant differences reported. The intervention was generally well tolerated, although insomnia was reported in 10.0% of the 900 mg/day group.
- Study & population
- Randomized, blinded, placebo-controlled smoking-cessation trial in adults aged at least 18 years who smoked cigarettes and were willing to make a quit attempt.
- Intervention
- St.
- Key limitation
- Sample size was modest, with 39 and 40 participants in the two active arms, limiting power to detect small effects.
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Open PDFOriginal abstract
INTRODUCTION St. John's wort (SJW) is a widely used herbal supplement. The predominant mechanism(s) accounting for the activity of SJW in vivo are, however, unclear. The purpose of this study was to investigate the efficacy of SJW for smoking cessation. METHODS We conducted a randomized, blinded, placebo-controlled, three-arm, dose-ranging clinical trial. A total of 118 subjects were randomly allocated to receive SJW 300 mg, 600 mg, or a matching placebo tablet 3 times a day combined with a behavioral intervention for 12 weeks. Self-reported smoking abstinence was biochemically confirmed with expired air carbon monoxide. RESULTS Mean age of the study participants was 37.6 +/- 12.4 years; they smoked an average of 20.0 +/- 6.6 cigarettes per day for 20 +/- 12.1 years. The study dropout rate was high (43%). By intention-to-treat analysis, no significant differences were observed in abstinence rates at 12 and 24 weeks between SJW dose groups and placebo. SJW did not attenuate withdrawal symptoms among abstinent subjects. Abstinence rates did not differ by study group among subjects who took at least 75% of their study medication. No significant side-effects were noted with SJW. CONCLUSIONS In this randomized trial, SJW did not increase smoking abstinence rates. Our data, in combination with data from other studies, suggest that SJW has little role in the treatment of tobacco dependence.