Introduction. Recent studies have revealed an increase in the consumption of dietary supplements including frequency of use of caffeine, which is addictive and potentially harmful in higher doses. Energy drinks include high doses of caffeine and are particularly targeted at young people. Objective.The aim of the study was to investigate the frequency of use of caffeine-containing energy products, associated factors and understanding the associated side-effects in university students. Materials and method. A cross-sectional questionnaire-based survey was conducted among students of the 5 largest Universities in Krakow. Statistical significance was set at the 0.05 level. Results. Around 35% of respondents reported the use of different supplements including high doses of caffeine. Frequency of caffeine-containing products consumption was significantly higher in female students compering to males. Also, those respondents who originated from big cities were more likely to use caffeine-containing products. The study revealed that these substances were also more popular among those participants who study economics. Most students use these substances in order to reduce feeling tired and the duration of sleep, others mainly to increase concentration prior to examinations. Almost one fourth of the group who used these substances admitted to having experienced some sideeffects in the past. They suffered mainly from insomnia, but also from excessive stimulation and muscle trembling. Almost half of the substances users did not know of any potential side-effects. Conclusions. Attempts should be made to increase public awareness of the side-effects of these substances, particularly among the student population. These campaigns should be targeted especially at female students who come from bigger cities. This study is a step towards drawing attention to this issue.