Preliminary findings from a survey of more than 36,000 adult substance users in Europe suggest that use of alcohol, tobacco, cannabis and other illicit substances changed for about half of respondents during the first wave of the SARS-CoV-2 pandemic in spring 2020. Overall patterns suggest that more users tended to reduce rather than increase their alcohol use during this period, whilst the opposite was observed for tobacco and cannabis use. Taking into account uncertainty intervals, this overall pattern of change was only corroborated in some countries. For illicit drug use, there was no clear pattern of change in the overall sample.

Before discussing the implications of the results, we would like to highlight some key limitations of this study. First and foremost, we present self-reported changes in substance use, which were assessed retrospectively by survey respondents. Retrospective assessment of substance use is known to be affected by recall and social desirability biases, which lead to underreporting of use (for alcohol, see e.g. [34]; for illicit substance use, see e.g. [35]). The same biases, in addition to subjective interpretation, may have further distorted the meaning of the categories “much less” and “much more”, which may not indicate equal amounts/frequencies and likely depend on levels of baseline use. Further, we cannot exclude differences in reporting accuracy between substances, as potential stigmatization of illicit drug use is usually greater compared to legally regulated substances, resulting in a more pronounced social desirability bias for illicit drug use.

Second, we collected data from a convenience sample employing different dissemination strategies [25, 36], which may limit comparability across countries. Thus, results of our survey may not represent the population of substance users in either Europe as a whole, or with regard to the individual countries studied. As with other web-based surveys, certain subgroups are not well captured (e.g., older adults) or are potentially excluded from participation (e.g., those without internet access) altogether. Whilst this is a recognised problem in alcohol and other substance use surveys (for a discussion, see [37, 38]), we still see value in these data, especially in times of an acute public health crisis. Further, despite the relatively heterogeneous recruitment techniques used to engage substance users in different countries (for a summary, see [25]), the fact that we found consistent patterns across countries reduces the likelihood that our findings result from selection bias. Additionally, sample weights were applied to adjust for sample bias with respect to skewed representation of sex, age and education. In light of these limitations, we suggest the data presented here should be interpreted as trends for a general internet population that warrant further investigation at the country level. Future research in this area should employ a multi-faceted approach, combining routine statistics (such as sales or treatment demand data) as well as quantitative and qualitative surveys, to provide a more comprehensive and representative picture of substance use during the pandemic.

Keeping these limitations in mind, our findings reveal some important insights on substance use during the pandemic. For alcohol, a larger proportion of survey participants reported decreased use than increased use. This average decrease was particularly pronounced in relation to the frequency of HED events, where a decrease was reported twice as often as an increase. This European finding is consistent with findings from some (e.g., [13, 23]), albeit not all (e.g., [11, 39]), previous surveys of alcohol consumption during the pandemic. It remains unclear whether the changes presented here are phenomena specific to the current pandemic or merely represent normal year-to-year or seasonal fluctuations. However, as some countries have partially banned alcohol sales during the first months of the pandemic, future evaluation might provide more clarity on this matter [40]. Moreover, the different lockdown measures in response to the pandemic, including their duration and the respective impact on alcohol outlets such as bars and restaurants, add to the observed complexity of comparison across countries. Additional country analyses of the same data have indicated that the overall decreases in alcohol use found across Europe mask increases in consumption reported by previously heavy drinking individuals [41]. Routine clinical data from addiction outpatient services in Barcelona, Spain, suggest a doubling of positive alcohol urine screening tests [42], while alcohol withdrawal treatment demand in Bangalore, India, has reportedly spiked following lockdowns which included a complete halt of alcohol sales [43]. Potentially increasing alcohol use among heavier drinkers can be linked to an elevated risk of complications following a SARS-CoV-2 infection [44], but also to other alcohol-attributable harm, thus, an average decrease of alcohol use does not necessarily imply a lower alcohol-attributable societal burden.

For tobacco use, about twice as many survey participants who are current smokers reported to increase their use compared to those reporting a decrease, which also reflects findings from several other surveys (e.g. [11, 39]) and trend studies [45]. This increase in smoking could be seen as a reaction to the stress in experiencing the pandemic [46, 47] or to more time spent at home, where less restrictive smoking policies exist than at the workplace. Our results are indicative of an overall increase in tobacco use which is also corroborated by preliminary sales data available from Germany [48], Norway [49], and the UK [50]. While possible changes in unrecorded tobacco supply are yet to be considered to determine changes in population level tobacco use, an upward trend would constitute a severe setback in reaching global goals to reduce smoking prevalence [51] and the attributable burden, both of which remain high in the European region [52, 53]. Given that one in six EU deaths from non-communicable diseases was attributable to tobacco use in 2017 [54], this could hamper the projected achievements of reductions in mortality from cancers and cardiovascular diseases in the region (for a recent update on progress in reducing the non-communicable disease burden, see [55]).

For cannabis, an overall of current users to increase their consumption was identified, although country-level analyses only corroborated this pattern for 3 out of 21 countries. This pattern is consistent with longitudinal findings from the Netherlands [56] and cross-sectional survey results from Germany [57]. Further, the results may, to some extent, represent a continuation of trajectories observed in recent years [58, 59]. The increased use may be related both to stress as well as the arrival of unexpected leisure time or boredom related to lockdown. It has been noted that during the early months of the pandemic, darknet sales of cannabis in Europe increased and shifted to smaller quantities [20]. While these data provide information on changes in purchasing behaviour during this period, they should be triangulated with survey data in order to corroborate changes in use behaviour. However, unlike alcohol and tobacco use (see e.g., European Health Interview Survey [60]), there is no ongoing comparative general population survey assessing cannabis use in Europe. In light of increasing potency levels [61], treatment demand [58], unintentional intoxications (e.g. among infants [62]), and possibly increasing use during the pandemic, comparative cannabis use survey data is warranted.

For other illicit substances, the sample size of users was relatively small so we did not observe a clear pattern of change in the overall sample and, at country level, an average decrease in Portugal only. Consequently, our findings reveal no consistent pattern across countries, which is not unexpected given that we asked about a heterogeneous class of substances (“illicit drugs (other than cannabis)”) and changes in use behavior will largely depend on the type of substance [24]. For instance, use of substances such as 3,4-Methylenedioxy​methamphetamine (MDMA) may decrease with the closure of the night-time economy, while amphetamine use may increase if used to enhance productivity and to cope with stress [63]. Notably, increases in opioid overdose emergency admissions and deaths following lockdown have been reported in some US states [64–66], while German data from the first 6 months of 2020 indicate a 13% increase of drug overdose deaths as compared to 2019 [67], which may be due in part to changing purity and resulting uncertainties for titration [18].

Finally, we would like to highlight that, on average, users reported increases in their tobacco and cannabis use but decreases in their alcohol use during the first wave of the pandemic. One possible explanation may be related to the different contexts of use of these substances. While most tobacco and cannabis users may use the drug(s) regardless of social gatherings, alcohol use remains a social drug for most users. Another hypothesis is that users of tobacco or cannabis may have experienced pandemic-induced stress to a larger extent or more intensely than alcohol users, and that they attempted to cope with such stress by increasing their substance use. However, we cannot rule out alternative explanations, such as differential sampling bias (heavy users of certain substances, who are also more likely to increase their use, are more prone to use the internet than other substance users) or differences in use patterns prior to the pandemic. Future studies examining changes of substance use should therefore not only account for pre-pandemic use patterns, but also for context of use (e.g., social, party, work).