BACKGROUND: A recent rigorous study has shown that cytisine, a low-cost drug, is 
effective for smoking cessation. A number of earlier studies exist, mostly from 
former communist countries where cytisine has been used since the 1960s. The key 
question now is whether there is sufficient evidence to warrant licensing 
cytisine or whether more work is needed. A systematic review was undertaken to 
assess the efficacy of cytisine in smoking cessation.
METHODS: The Cochrane Library, CINAHL, Embase, Medline and PsycINFO databases 
were searched for relevant data. Data from controlled trials were entered into 
two separate meta-analyses. The first considered the strictest definition of 
outcome and longest follow-up from all available studies and the second pooled 
outcomes from studies with biochemically validated abstinence and follow-up of 6 
months or longer.
RESULTS: Eight controlled trials were identified. Seven trials provided 
extractable data and, when pooled (first meta-analysis), produced a risk ratio 
(RR) of 1.57 (95% CI 1.42 to 1.74). Data from two high-quality studies (second 
meta-analysis) produced a pooled RR of 3.29 (95% CI 1.84 to 5.90). Patients on 
cytisine reported more gastrointestinal symptoms than patients on placebo 
(RR=1.76, 95% CI 1.28 to 2.42). There was no difference in overall reports of 
adverse events and no specific safety concerns emerged.
CONCLUSIONS: Cytisine is an effective treatment for smoking cessation with 
efficacy comparable to that of other currently licensed treatments. Given its 
low cost and potential for public health benefit, expedited licensing of 
cytisine for smoking cessation is warranted.