Although data on the prevalence of problematic cocaine use and addiction are lacking in Switzerland and many other developed countries, there is no doubt that, in line with other countries, cocaine use has increased in Switzerland in recent years [1, 2]. Over the past ten years, the number of cocaine-related disorder treatments has quintupled in outpatient treatment and advisory services . In 2005, resident institutions reported that, for the first time in history, cocaine outstripped opiates as the main substance used . This trend has also been observed in outpatient units . Further evidence of increased cocaine consumption has been found by quantifying cocaine concentrations in sewage effluents  and in recent HBSC student surveys . The abovementioned increase in treatment requests likely reflects only a minority of cocaine users. Presumably, the majority of users consume cocaine on a quasi-controlled basis, whereas only a small fraction of consumers is likely to take advantage of available treatments . However, it is expected that some users will switch from controlled to problematic use . For those users, interventions that follow the principle of concurrent cover (i.e., non-invasive, low-cost interventions in which therapeutic intensity can be enhanced according to need) appear appropriate.
In recent times, the international literature has described treatment models that target the general population. In addition to supplying informative measures at the level of primary and secondary prevention, the literature also offers web-based self-help tools for problematic substance users, which is in line with tertiary prevention [[8–10]].
Web-based self-help programs that reduce problematic consumption are able to reach "hidden" consumer groups in the general population due to their low treatment threshold and non-restrictive setting for intervention . Furthermore, these programs show a remarkably positive cost-benefit relation , which is of interest in Switzerland and other industrialised countries suffering from exorbitant health costs. Such programs, however, have been primarily tested on individuals with problematic alcohol and cannabis consumption but not on cocaine-dependent individuals [[9, 10, 13]].
Therefore, Snow Control, a six-week self-help therapy for problematic cocaine users who intend to reduce or stop consuming and have access to the Internet was developed in 2010. Snow Control is based on methods of Cognitive Behavioural Therapy (CBT) that have been tested on cocaine addicts [14, 15], principles of Motivational Interviewing , current self-control practices and the established Relapse-Prevention Model [[17–19]].
The therapy is structured into three parts and includes the following eight modules that are activated for access week by week (modules 1 to 4) and four additional voluntary modules (module 5 to 8) that can be activated during week 4-6:
After the completion of part 1, each login in the therapy group will direct the participant to the consumption diary. The participants are asked to determine the amount of cocaine they plan to consume in the next 7 days and to specify the amount of cocaine consumed in the past 7 days into their consumption diary. After the completion of the consumption diary, they are directed to their weekly module (part 2 to be worked through in the above mentioned order; part 3 to be worked through in an optional order).
To assess the effectiveness of the Snow Control therapy, an appropriate psycho-educative online control condition was developed. Participants in the control condition receive eight psycho-educative information modules on the risks, potential harms and other important information about cocaine consumption. The frequency of the control condition is comparable to the 6 weeks of intervention; however, it does not include the presentation of a consumption diary first. After having read each of the information modules, the participants are invited to participate in a weekly quiz to evaluate their information knowledge.