Our results show that among the MSM who attended sexual health clinics in the study period, and who were, on average, 29 years old, 40% reported being HIV positive and engaging in CAS risk behaviors. Almost a quarter (24.2%) of these men reported having used one or more sex drugs in the past three months, 76.2% used alcohol, and more than a quarter (29.2%) reported binge drinking. The MSM in this sample were classified into three general LCA categories of substance users: Class 1 principally identified alcohol users in the previous 30 days; Class 2 identified non-daily smokers, alcohol users, and binge drinkers; and Class 3 identified polysubstance users (smoking, alcohol, marijuana, and drugs). Our results demonstrate that members of the Class 3 group were characterized by a high probability of using alcohol and sex-drugs: crystal meth, traumazol, EDDs, and poppers. In the adjusted models, being a member of the Class 3 group was associated with having greater sexual risk behaviors (CAS behaviors) and serosorting, being younger, and having a high level of educational attainment.

Prior studies have demonstrated that some MSM are motivated to drink to enhance sex, which is also associated with greater alcohol use [7,35,36]. All LCA profiles had markedly higher likelihoods of alcohol use in the last month. However, in Class 2, more than 55% engaged in binge drinking. It is known that alcohol consumption is associated with AIDS-related deaths [37]; research has shown that alcohol use, especially binge drinking, is associated with an increase in CAS behaviors [38,39]. We found no association in CAS behaviors and serosorting between Classes 1 and 2, possibly because they are less likely to use sex-drugs.

Our results show a high use of drugs among young MSM who attend sexual health clinics, which is consistent with other existing studies [13,22,26,40]. Class 3 reported using marijuana and a wide range of drugs, including drugs during sex, i.e., crystal meth, EDDs, traumazol, and poppers, as well as other drugs: cocaine, benzodiazepine, GHB, mushrooms, ketamine, inhalants, and opioids. This is consistent with studies that have used LCA, where membership in a higher-risk subclass is due to a high proportion of drug use. For example, in Chan et al., Class 3 had the highest number of MSM who reported consuming alcohol or drugs during sex [40]. McCarty-Caplan et al. found that four latent classes, defined as ‘low drug use’, ’moderate drug use’, ’sex drug use’, and ‘polydrug use’, were classes that showed higher probabilities of using all other drugs assessed [13]. Lim et al. found three latent classes: ‘negligible substance use’, whose members reported having no substance use or using any substance in moderation; ‘soft substance use’, whose members used poppers, ecstasy, and alcohol before sex; and ‘amphetamine-type stimulants’ (ATS), whose members used stimulants (crystal meth, ecstasy), EDDs, and recreational drugs before having sex. The types of drugs used by MSM in these last two groups were markedly different. The men in the soft substance use group mostly used poppers and ecstasy, while those in the ATS group used crystal meth, ecstasy, ketamine, EDDs, and recreational drugs before sex [26]. Achterbergh et al. identified five latent classes of users: ‘no substance users’, ‘alcohol users’, ‘nitrite and EDD users’, ‘polydrug users’, and ‘chem-users’. The members of the last two classes were those with the highest consumption of drugs, especially sex-drugs: GHB/GBL, crystal meth, ketamine, and mephedrone [22].

We found subgroups of MSM who reported tobacco use. Card et al. evaluated substance use contextualized by sociocultural experiences, and they identified six latent classes: ‘assorted drug use’, ‘club drug use’ (e.g., ecstasy, mushrooms, LSD), ‘illicit drug use’ (e.g., heroin, codeine, oxycodone, crack), ‘sex drug use’ (e.g., GHB, poppers, EDDs, crystalline methamphetamine), ‘conventional drug use’ (e.g., tobacco, alcohol, and marijuana), and ‘limited drug use’. Card et al. found that conventional drug use was 100% for alcohol use, 80% for marijuana use, and 43% for tobacco use. Compared to our data, the prevalence of use of these substances was lower for alcohol (76%) and marijuana (29%), but the same for tobacco (non-daily smokers—29% and daily smokers—13%). Perhaps because of social norms, regulations, and law enforcement related to the use of these substances [41]. In another study, Newcomb et al. [6] conducted research on young MSM and identified three classes: ‘alcohol and marijuana users’, ‘polysubstance users’, and ‘low marijuana users’. They found a low (12.6%) prevalence of daily smokers. Although it is not possible to make a comparison due to the measurement of variables and age, the proportion of smokers in our sample was low compared to the proportion of current smokers (16.8%), only in Class 3 was it higher than the proportion of current smokers in Mexico [42].

Thus, in general, the typologies of substance use by MSM in Mexico appeared similar to studies conducted in Malaysia [26], France [27], and Chicago, USA [13]. MSM in this study reported a high probability of using drugs, suggesting that some MSM in Mexico use drugs for sexual encounters. With the advance in antiretroviral treatments for HIV infection, the perception of risk has changed and has produced an increase in sexual risk behaviors [43,44]. In our study, membership in Class 3 was associated with practices such as CAS behaviors and serosorting. A longitudinal cohort study between HIV-positive and HIV-negative MSM who were frequent users of alcohol and crystal meth showed that they had more episodes of condomless sex, thereby failing to follow through on their original intentions to engage in sexual intercourse with partners of the same serostatus [19]. In a study conducted in France [27], three latent classes of sexual positioning and serosorting profiles were identified: ‘majority top/serosorters’, ‘versatile/low partners’, and ‘majority bottom/some serosorters’. The majority top/serosorters group had the highest probability of condomless serosorting (72%), although the authors found no association with drug use before or during sex.

A review of the literature on CAS behaviors [45] showed that, in regard to such behaviors, multiple factors converged, including homonegativity, community norms, intimacy with a partner, and drug use. Likewise, HIV-positive serostatus might be a predictor of CAS sex. Halkitis reported that a large number (41.2%) of self-identified CAS participants in his sample were HIV positive [46]. Tobin et al. found three latent classes: ‘poly-users’, ‘alcohol/marijuana users’, and ‘low substance users’ [23]. The results showed that both the alcohol/marijuana and poly-user classes were significantly more likely to engage in sex under the influence of drugs and alcohol. In Mexico, a study found that MSM engaging in CAS behaviors was due to a change in risk perception, with access to antiretroviral therapy [47]. Different studies in Mexico have shown growing concern for addiction to crystal meth as a particular drug that may potentiate new cases of HIV among MSM due to its potential to enhance sexual desire and CAS with multiple partners [48,49].

Strategies to detect and address alcohol and substance use disorders should be considered based on a comprehensive approach that considers the needs of gay, bisexual, and other MSM, including their mental health. Risk reduction and harm reduction strategies can be particularly beneficial in preventing drug-related harm (e.g., overdose, addiction) and sexual health problems, including HIV and STIs [50]. In 2020, the brief guide for the implementation of the risk and harm reduction approach with drug users was published, in which a series of strategies was provided, such as sharing information on the effects of drugs and their possible combinations and information on establishments to access counseling or treatment, antiretroviral therapy, as well as condom distribution programs; interventions must also be carried out in nightclubs and festivals in order to reduce risks. These are some of the actions that could have positive results for MSM [50].

Governments and healthcare providers must implement programs that are sensitive to people with diverse sexual orientations and practices, without discrimination or stigmatizing views regarding drug use, preserving the right to health protection and non-discrimination, to contribute to the consolidation of a culture that respects human rights [51].