Tobacco and cannabis are interrelated in a unique, multi-dimensional manner, with some connecting mechanisms that are distinct from the co-use of drugs in general . Two of them are the shared route of administration (i.e., both substances are smoked) and co-administration (“mulling”, i.e., adding tobacco to cannabis joints, or blunts, i.e., rolling cannabis in cigar paper). Mulling is the most common way of using cannabis in Europe . Epidemiological data show that tobacco smoking is more prevalent among those who consume cannabis compared to the total population. In a study in the United States, 74% of the marijuana users smoked cigarettes compared to 29% of the nonusers . On the other hand, cannabis use is more common among tobacco smokers than among tobacco abstainers. In the National Survey on Drug Use and Health (NSDUH) in the United States, the 30 days prevalence of cannabis use was 36% among tobacco smokers compared to 11% among non-smokers . In a general population survey on tobacco use in Switzerland, cannabis use during the 12 months before the survey was reported by 28% of the adolescents who smoked tobacco daily compared to 9% and 2% of the adolescents who were ex- and never-smokers, respectively .
Investigations examining the initiation of use, the transition to regular use, and the cessation of tobacco and cannabis use exemplify this interrelation. Tobacco use can act as a gateway to cannabis use , but the reverse, i.e., cannabis use acting as a gateway to tobacco use, has also been observed [7, 8]. Additionally, the probability of a transition from occasional to regular tobacco smoking and nicotine dependence is higher in smokers who also use cannabis [7, 9]. Similarly, (adolescent) cannabis users who also smoke tobacco seem to be at higher risk for regular cannabis use and cannabis dependence in young adulthood compared with cannabis-only users .
Regarding the cessation of tobacco use, longitudinal observational studies have demonstrated that tobacco smokers who also consumed cannabis made fewer attempts to quit using tobacco  and were less likely to successfully quit using tobacco compared with tobacco-only smokers . Furthermore, cessation programs that exclusively address tobacco consumption appear to be less effective for individuals who also consume cannabis [13, 14]. A balancing effect is one problem that co-smokers may be confronted with when wanting to stop using only one of the substances. It has been shown that the cessation of one substance often co-occurs with an increased use of the other substance [15–17]. These findings highlight the importance of accounting for concurrent tobacco and cannabis use when planning and evaluating interventions.
Despite this evidence, current cessation programs typically focus on one substance while only addressing the other substance either marginally or not at all. To our knowledge, no integrative smoking cessation program (ISCP) targeting co-smokers of cigarettes and cannabis in a group setting has been designed.
However, results of concurrent treatments of tobacco and alcohol dependence [18, 19] and tobacco and illicit substance use (e.g., opiates; ) have been published. Additionally, some brief interventions targeting multiple substance use have shown promising results [21–23]. These findings demonstrate that it is feasible to combine a tobacco cessation intervention with an intervention that targets a second substance. Compared with single interventions, double interventions do not necessarily overstrain participants and reduce abstinence rates; instead, they generate putatively better outcomes with regard to one or both targeted behaviours [24, 25].
The separate treatment histories surrounding tobacco and cannabis may be explained by the different legal statuses of the two substances that are often the subject of political discourse and election campaigns. In Switzerland for example, tobacco is categorised as a licit substance, while cannabis is an illicit drug. The divisions of the Swiss government that deal with these substances are both organisationally and financially separated from each other and, currently, so is the funding for prevention programs and research projects. Another explanation for the lack of combined treatment for tobacco and cannabis use may be the historical development of treatment and prevention systems in many industrialised countries. Treatment of cannabis dependence and co-occurring mental health problems is provided by the psychiatric systems of many countries. In contrast, tobacco cessation is possible without the involvement of psychiatrists and is part of the more general public health systems [24, 25] that typically involve general health supply services. In Switzerland, health insurance coverage differs between the substances; while cannabis treatment in psychiatric services is covered by basic health insurance, smokers themselves are required to pay for nicotine replacement therapy and courses for tobacco cessation.
In recent reviews, researchers have stressed the need to develop and evaluate combined interventions for tobacco and cannabis users [1, 26, 27]. Agrawal and colleagues found evidence that dual abstinence may predict better cessation outcomes and therefore suggested developing out-patient treatment models .
The aim of the current study was to develop an ISCP. This process was accomplished in three steps, which will be explicated in this report. First, a preliminary study clarified whether there was a demand for an ISCP. Second, after having identified the demand, explicit information regarding co-smokers’ attitudes towards tobacco and cannabis and the association between both substances was collected for use when developing an ISCP. Moreover, co-smokers’ relevant experiences regarding quitting one or both substances simultaneously were collected. Third, based on the information gained during the second step, an ISCP was developed tailored to co-smokers of cigarettes and cannabis. This program incorporates the established therapeutic principles and strategies of former tobacco and cannabis cessation programs and takes into account reasonable concepts and ideas from the ongoing discussion about the mechanisms underlying the co-use of tobacco and cannabis and potential dependency problems.