Our findings suggest that the majority of our responders did not notice significant changes in alcohol, tobacco, marijuana and THC and hard drugs intake resulting from the pandemic situation. Nearly the same number of students reported a decrease and increase in both drinking alcohol and smoking. Much more participants noted a decrease than an increase in usage of marijuana, and products containing THC and hard drugs. Most of the responders who reported a decrease in alcohol, tobacco, marijuana, and hard drugs intake chose that it had decreased in the highest possible way (answer “−5”). Those findings can be explained by the social customs connected with using drugs, tobacco, and alcohol in Poland. Studies are the time when many students move to different cities, live with roommates, or in dormitories where they often gather and party together. Previous research showed that an increase in the consumption of alcoholic drinks was accompanied by an increase in overall drinking occasions [24,25]. The closure of universities and social gathering sites combined with the onset of online classes could cause a significant decrease in drinking occasions [24].

A decrease in self-perceived psychological well-being was significantly related to self-estimated higher consumption of alcohol and tobacco and was not significantly correlated with self-perceived usage of marijuana and products containing THC, or hard drugs for general study population. Although, for particular subgroups results slightly differ, the major direction of changes has been observed (see Table 4). The negative effect of the COVID-19 pandemic on mental health is commonly known [22,26]. A different study conducted at the beginning of the pandemic has also revealed that those students who had reported depression or anxiety demonstrated a higher increase in alcohol consumption [27]. Long quarantine duration, infection fears, frustration, boredom, inadequate information had impacted mental health and well-being. In those stressful situations, people tended to overuse stimulants [28]. Therefore, it is particularly important to pay attention to people with poor psychological conditions, to prevent them from becoming addicts.

Tobacco users were divided into traditional cigarettes smokers and alternative products containing tobacco (such as e-cigarettes, IQOS, HTPs) users. According to the data provided by the Chief Sanitary Inspectorate from 2019, more than one-fifth of Poles admit to habitual (every day) smoking of traditional cigarettes [29]. This result is lower than in the previous survey, conducted in 2017. The research showed that men were more frequent smokers than women (24% vs. 18%). The percentage of smoking men was increasing almost proportionally with age. In the age group of 20–29, 7% of women and 24% of men admitted to habitual smoking. In the case of electronic cigarettes (e-cigarettes), the same data showed that 1% of all Poles smoke e-cigarettes, and 4% of them declared that they had used them at least once. The most frequently indicated reasons for smoking e-cigarettes were the fashion for smoking them (28%), a belief that e-cigarettes are better for health (17%), saving money (14%) and willingness to quit smoking (13%). Comparing our respondents with the data from the population of age 20–29 we can notice a lower percentage of men (16.5% vs. 24%) and a higher percentage of women (11% vs. 7%) smoking traditional cigarettes. Our study also revealed that a significantly higher percentage of our responders reached for alternative cigarettes (used them at least once) in comparison to the data from 2019 (28% vs. 4%). The commonly observed phenomenon is dual usage (simultaneous use of traditional and alternative cigarettes). More than half of our respondents, who were traditional smokers were also dual smokers. As previously mentioned, alternative products containing tobacco are gaining popularity especially among adolescent and younger populations [17,30]. They are more attractive for young people due to a variety of flavors, especially the sweet fruit variants. Despite they are considered to be less harmful, they can be more addictive than traditional ones and their long-term effect on the human body is still unknown [16]. Numerous studies have reported that current smokers, cigarette users or dual users are more likely to perceive e-cigarettes as safe for health [30,31]. According to the World Health Organization statement, there is no evidence that HTPs are less harmful than conventional cigarettes [32]. The risk of respiratory tract infections in smokers may be increased through various mechanisms. It increases the risk of several types of pneumonia infection and influenza [33]. From the analysis of available studies, it appears that patients with a history of smoking have a higher likelihood of developing more severe symptoms of COVID-19 disease than non-smokers [34]. Moreover, smokers have a higher probability of COVID-19 progression [35]. Electronic cigarettes and other alternative devices are unlikely to be a safer option regarding COVID-19-related risks. Since they use tobacco and produce smoke or vapor, they may cause the infectious lung damage observed with traditional cigarettes [33].

The two reports considering alcohol drinking, first from the State Agency for Solving Alcohol Problems, and second from the Public Opinion Research Center from 2019, showed an increase in alcohol consumption in Poland [36,37]. Between 2010 and 2019, the number of men who regularly drink alcohol decreased, but the number of regularly drinking women increased. A 58.5% of our responders drank alcohol regularly (once a month or often). This number was higher for men (67.37%) than for women (56.12%). In addition, people who reported more frequent intake of alcohol also reported a worse self-perceived pandemic impact on that intake. More than one-fourth of responders reported that they drank more alcohol than before the pandemic. Another study conducted at the beginning of the pandemic revealed that over 28% of its participants had drunk at risk levels [25]. Alcohol consumption is a common problem among Polish students [38,39] and it increases among both males and females [39]. A pre-pandemic study among university students revealed a two-fold increase in the number of Polish male and female students who abused alcohol to blackout levels between 2000 and 2016 [39]. The same study revealed an increase in the number of students drinking alcohol once a month and a decrease in the number of abstainers [39]. Alcohol increases aggression by causing changes within the person organism, e.g.,: it reduces intellectual functioning [40]. High alcohol intake is closely linked to the risk and severity of interpersonal violence, such as intimate partner violence and sexual violence [41].

There were no significant differences between gender and declared self-perceived pandemic impact on the usage of the considered substances. However, a slightly higher percentage of men admitted to smoking traditional cigarettes (16.5% of males and 12.32% of females smoked at least one cigarette a day). A higher proportion of men reached for alternative cigarettes (34.34% of men and 26.54% of women smoked them at least occasionally). This is in line with previous reports from Poland [30], Europe, and the United States [42,43], which revealed that women were less likely to reach for cigarettes. In our study, a higher percentage of women declared abstinence (10.44% men vs. 12.24% women). It is known that women drink lower amounts of alcohol than men and, in consequence, have fewer problems with the law, family, and health. Moreover, their risk of death from over usage of alcohol is also lower [39]. Compared to men, more women are lifetime abstainers, drink less, and are less likely to engage in problem drinking, develop alcohol-related disorders or alcohol withdrawal symptoms [44,45].

There were also no strong differences between being a MUS and the reported self-perceived worst pandemic impact of any of the intake of the considered substance. The lower percentage of MUS were abstinent (9.52% MUS compared with 14.29% NMUS) but a higher percentage of them were non-smokers of traditional cigarettes (90.48% MUS compared with 85.14% NMUS). Nearly the same percentage of those groups admitted to smoking alternative cigarettes at least occasionally (72.53% MUS compared with 71.14% NMUS).