The use of psychotropic drugs among students is well known, but very few studies have been carried out outside North America, and data on Switzerland are particularly scarce. This study investigates the factors that determine the use of drugs and psychotropic substances among students at the University of Lausanne. Our hypotheses were that study pressure could lead to psychotropic drug use; that use could be either regular or experimental; and that users and non-users would have different opinions about the reasons for use and the consequences. Based on a convenience sample (n = 1199) collected by Master’s students from other university students as part of a course given in 2019, our three hypotheses were confirmed. The use of psychotropic drugs is well associated with poorer academic performance. Regarding frequency of use, certain types of psychotropic drugs are used regularly (e.g. antidepressants), while others are used on occasionally (e.g. tranquilizers). Psychotropic substances such as cannabis and cocaine, on the other hand, are mainly used irregularly. Finally, the majority of psychotropic drug users report that they use them as part of their medical treatment, while the majority of non-users suggest that they use them mainly to reduce anxiety and stress in everyday life and at school. Our results show that Switzerland, like other countries, is affected by the phenomenon of psychotropic drug use by students, even outside medical supervision. Accordingly, better information on the negative effects of these substances should then be provided to all university students.