Discussion

This study provides a systematic review and meta-estimate of the prevalence of the use of intoxicating substances before or during sex among young adults. To the best of our knowledge, this is the first study that specifically examines the prevalence of this behavior in this age grouping. Previous literature has mainly focused on analyzing SDU in MSM communities (Edmundson et al., 2018; Guerra et al., 2020; Íncera-Fernández et al., 2021; Lafortune et al., 2021; Maxwell et al., 2019), which makes it difficult to assess comparability.

Our results have revealed a high global prevalence of the use of intoxicating substances before or during sex, that is, 28–47% of young adults. This high prevalence estimate concurs with those reported in the abovementioned review studies that specifically focused on examining SDU among MSM (Edmundson et al., 2018; Maxwell et al., 2019). Nonetheless, comparisons should be made with caution, considering the differences in the meta-analytical samples. The results obtained in this research also indicate that the prevalence of using an intoxicating substance before or during sex varies significantly according to the specific substance used. The consumption of alcohol, marijuana, and ecstasy had significantly higher prevalences than those referring to the use of cocaine, heroin, methamphetamine, and GHB, perhaps due to differences in their acceptance, accessibility, cost, addictive potential, and short- and medium-term health and social consequences (Bourne et al., 2014; Graupensperger et al., 2021; Jackson et al., 2021; Rosińska et al., 2018). It is also likely that higher prevalence rates and the decision to use one or another substance depends on the particular effects it causes during sex. Alcohol may be used to become disinhibited before sex (Herbenick et al., 2021), even though it may make it more difficult to reach orgasm and reduce quality of sex (George, 2019; Palamar et al., 2018a). Ecstasy, on the other hand, may affect sexual experience the most, for example, by prolonging erection duration (Coyer et al., 2022). Future research should go more deeply into the reasons that lead to the choice of one or another drug, considering the sexual act as a complex process (e.g., from flirtation right through to after-sex behaviors), distinguishing the type and quantity of substances consumed, and the order in which they are consumed, if more than one is involved. The decision to consume one drug or another before or during sex may also be associated with individual characteristics (e.g., conception of sexuality and attitudes towards substance use for pleasure-seeking) and demographic characteristics (e.g., age and work-related aspects, including income level) and, for example, older cohorts may use higher-cost and harder-to-access substances (e.g., methamphetamine and cocaine). Regarding the geographical origin of samples, it was found that the estimated prevalence of alcohol use before or during sex varied significantly and was lowest on the African continent. Geographical comparisons pose a particular challenge due to significant continent-level, country-level, region-level, and population subgroup differences. Though this study’s comparisons are made for descriptive purposes only, several multi-level societal and individual factors may explain the observed differences in alcohol consumption patterns, including economic development, cultural aspects, such as cultural norms and religious beliefs, and societal and political aspects, such as rules concerning drug access and use, and the effectiveness of alcohol control policies (Addo et al., 2018). Future studies may further explore such factors in order to gain more insight into the driving forces behind such variations.

The meta-regression analyses of this study additionally indicate that the prevalence of using intoxicating substances before or during sex differs significantly as a function of the ethnic composition of samples. When considering alcohol, the prevalence was significantly higher in studies with a higher proportion of ethnic whites in their samples. This is in agreement with a previous meta-analysis suggesting that risky sex and drug-use behaviors were reported most frequently by studies that sampled more ethnic whites (Cunningham et al., 2017). However, to our knowledge, reasons for such differences have not been examined yet in the literature. Previous empirical studies have suggested that individual developmental trajectories and socio-cultural and economic factors may help explain ethnic trends and differences in drug use among adolescents and young adults (Chen & Jacobson, 2012; Evans et al., 2017; Vaughn et al., 2018), with white youths having higher rates of illicit drug and alcohol abuse (Johnston et al., 2019; Jones et al., 2020). Future research might explore such aspects in order to improve our understanding of protective and risk exposure factors that may elucidate potential ethnic differences in the use of intoxicating substances before or during sex. However, when considering the global prevalence, a significant inverse relationship is seen. This opposing result is not directly interpretable, since there may be compensatory effects deriving from raw measures that do not distinguish between substances (Cunningham et al., 2017). Other demographic and sexual variables, such as gender, age or sexual orientation, did not show statistically significant effects on the prevalence of intoxicating substance use before or during sex. Regarding gender, for example, the findings of our meta-analysis concur with recent empirical studies suggesting that women present rates of alcohol or other substance use similar to that of men (Ford et al., 2021b; McKetta et al., 2022), although these studies did not focus on consumption before or during sexual activity. Developmental and sociocultural factors may explain the non-difference concerning these variables. For example, young adulthood is a developmental period characterized by the reinforcement of one’s own sexual identity and orientation, in which drugs and sex may be taken as a means of experiencing a variety of sexual practices in common pleasure-seeking (Arnett, 2005, 2007, 2014), regardless of the abovementioned individual participant characteristics (Bourne et al., 2015a; Piyaraj et al., 2018; Schmidt et al., 2016). This, together with previous arguments on the acceptance and accessibility of intoxicating substances in this age group, could offer a potential explanation of the results obtained in this study. Likewise, it should also be taken into account that a large part of our meta-analytical samples are studies with university or community samples, which possess certain common characteristics in their samples (e.g., age range, sexual-developmental stage, educational stage). As several researchers have observed, drug consumption and sex are common occurrences in college contexts and populations (Ford et al., 2021b; McKetta et al., 2022).

In addition to the above, the low quality of both our meta-analytic sample and its measures are an important aspect to highlight in our research. The majority of the studies reviewed had a high risk of bias, employing a cross-sectional design and non-probabilistic sampling techniques, with poor quality measures. The analysis of the measures used in the primary studies is a differential contribution of this review, yielding important gaps that need to be addressed. Indeed, sex under the influence of intoxicating substances appears to have hitherto been measured using “summary measures”, for example, mono-items with dichotomous response options, that not allow researchers to fully characterize the phenomenon (Wells et al., 2015). What may be more important than assessing whether participants have practiced sex under the influence of intoxicating substance or not is the frequency in which they have engaged in such activity. This is because the higher the frequency, the greater the probability of exposure to risks and consequences. Another result to be highlighted is that operational elements such as the specific sexual act (how), relationship type (with who), intentionality (purpose), willingness (whether solicited or not), and drug used were not made explicit in the majority of the studies reviewed. These elements were, indeed, often left up to the interpretation of respondents. The indefiniteness of key operational elements may, therefore, be behind the high dispersion in prevalence estimates. However, regarding drug type, our meta-analytical results do demonstrate that prevalence differences between individual drugs exist. Empirical research has also found that sexual practices under the influence of alcohol or other drugs differ somewhat, with the most frequently reported being exploratory acts (e.g., caressing or touching) (71%) and vaginal penetration (64%), while anal sex (12%) and sex with erotic toys (8%) were the least frequently reported (Castaño et al., 2012). Relevant circumstances such as unprotected sex or relationship type were indicated in only a few studies (Wells et al., 2015), while the willingness of participants was not made explicit in any measure. Nonetheless, it has been found that alcohol consumption before sex increases the probability of unprotected sex and higher-risk sexual encounters (i.e., with non-primary partners), increasing the likelihood of exposure to STIs and other risks (Rizwan et al., 2014). It should be noted that, although the result was not statistically significant, the proportion of STD/STI infections in the samples increased as the proportion of the use of alcohol before or during sex increased. Another key aspect is the specification of intentionality and purpose involved in the use of intoxicating substances before or during sex. Both are key indicators when differentiating between planned substance use with the purpose of enhancing sexual experience (e.g., SDU, chemsex) from substance use preceding casual sexual activity. All such measure quality related aspects reasonably warrant the wide credibility/prediction intervals obtained in our study. The lack of similar operationalizations with a minimum of precision makes it difficult to perform plausible comparisons among studies. Thus, clarifying these elements in operational definitions is a priority for future research that will allow a distinction to be made between planned and unplanned drug use before or during sex.

Educational Implications

Based on the results of this study and the prevalence of the use of intoxicating substances before or during sex, developing educational prevention programs referring to substance abuse and sexual risks remains imperative. Research recommends that such programs should revolve around four fundamental principles. Firstly, preventative efforts should be approached from an integrative perspective that contemplates biopsychological, social-communitarian and sexual aspects through multidisciplinary support (Donnadieu-Rigole et al., 2020). In particular, based on the results of the present study, educational interventions should take into account social-communitarian characteristic of participants, such as geographical and ethnic origins (e.g., focusing on more disadvantaged or higher risk populations, or on areas with higher SDU prevalence rates). Secondly, educational measures should take into account the implications, that is, the effects and consequences, of different substances and types of sexual practices (Lafortune et al., 2021; Saengdidtha et al., 2016). This is emphasized in studies that associate, for instance, substance use before or during sexual activity with negative health outcomes such as overdoses (Hammoud et al., 2017; Hegazi et al., 2017) or risky sexual practices such as unprotected sex (D’Anna et al., 2021; Ristuccia et al., 2018). Parents and educators should also inform young people on the implications and sexual health risks involved in having sexual experiences with someone you know personally, as opposed to someone met more casually. Thirdly, information on ethical issues relating to willingness and consent should be provided (Muehlenhard et al., 2016). Fourthly, young people might be encouraged to make greater use of sexual health resources if interventions were to focus more on the enjoyment of safe sex and sexual pleasure-seeking, in addition to discussing sexual risk behaviors (Ford et al., 2021a). Perhaps, a good starting point for educational interventions aimed at addressing SDU would be an analysis of needs and motivations that lead young adults to use intoxicating substances before or during sex. If the pursuit of pleasure emerges as the main motivation, it would, therefore, be a fundamental element to take into account in order to improve and adapt sexual health interventions. Interventions informing youths about decisions concerning where (e.g., spaces), how (e.g., substance characteristics in terms of effects and consequences; information on contraceptive methods; management of sexual acts and potential implications) and with whom they have sex may help them both to be more fully aware of their sexual practices and to avoid negative sexual experiences and adverse health outcomes. Ideally, such educational measures should be introduced at fairly early ages. Although it was non-significant, results of this meta-analysis showed that rates of alcohol use before or during sex increased as the proportion of sexually active participants in samples increased. Thus, it would be logical to start intervening at ages when young people begin to experiment with drugs and have their first sexual relations, with continuity spreading across into other educational courses and contexts, such as compulsory secondary education and university, and beyond school curricula, through ad hoc preventative educational programs, accessible community services, and information campaigns.

Limitations

This study has certain evident limitations, the main one being the low quality meta-analytical sample. Indeed, the predominant use of observational designs, non-probabilistic sampling techniques and non-validated measures was seen to introduce high levels of risk of bias in the primary studies. Secondly, the meta-analytical results showed a significant between-study variability, only partially explained by certain moderator variables. Undeniably, a considerable part of such variability remains unexplained and thus interpretable by means of the set of moderators and covariates considered. The high heterogeneity may also be attributed to a variety of other aspects such as research objectives, sample sizes, sample population characteristics and the specific measures used. Thirdly, several reviewed articles provided only a crude prevalence regarding the use of intoxicating substances before or during sex, without specifying the particular substance used, forcing us to analyze this as a generalized proxy. However, such results should be taken with caution because they may be biased and not necessarily reflect the effective prevalence rate. Fourthly, it was not possible to estimate the prevalence of the use of certain substances such as crack, speed, sedatives, LSD and ketamine before or during sex due to insufficient data. Furthermore, in the case of the global prevalence and of the use of alcohol, it was not possible to examine the effect of certain categorical and quantitative moderators due to an insufficient number of studies at some level. Fifthly, socioeconomic status could not be analyzed as a moderating variable due to deficiencies and divergences in how empirical studies have recorded and reported it (e.g., self-reported income level, social class, education level, occupation). Yet another limitation of this meta-analysis is that, despite including studies from a variety of countries, certain regions were particularly underrepresented. Data from developing countries and non-occidental countries were scarce. Lastly, because only 5 studies reported prevalence data of at least two or more substances, due to software limitations, it was not possible to compute a multi-level/multivariate meta-analysis assuming a generalized linear model. Developing this possibility would allow us to simultaneously analyze data from studies with multiple non-normally distributed outcomes, taking into account the dependence among effect sizes from the same study. Given all the above limitations, the generalizability of the meta-analytical results should be considered with caution.