OBJECTIVES The pattern of use of energy drinks, alone or combined with alcoholic beverages, was evaluated in a criteria sample. METHODS 136 volunteers aged 24 +/- 6 years, who had reported at least one previous use of energy drinks, answered a questionnaire on their pattern of use of energy drinks and alcoholic beverages. RESULTS Most of the sample (76%) reported using energy drinks in combination with alcoholic beverages, preferably whisky (90%), vodka (37%) and beer (13%). Most of the sample (79%) also reported using energy drinks alone. In the latter case, 61% of them reported not feeling any effect, 10% reported happiness, 9% euphoria, 9% insomnia, 7% uninhibited behavior and 24% increase in physical vigor. Out of those who reported combined use with alcohol, 14% told not to feel different, 38% increase happiness, 30% euphoria, 11% insomnia, 27% uninhibited behavior and 24% increase of physical vigor. High level of variability was observed in the number of lifetime uses of energy drinks (14 +/- 16). However, there was certain constancy in the number of cans ingested per occasion (1.5 +/- 0.7). CONCLUSIONS It was observed that the effects of energy drinks are variable, probably depending on the dose and individual sensitivity. Some reports suggest interaction with alcohol, expressed as an increase in the excitatory effects or reduction in the depressive effects. The possible pharmacological mechanisms underlying this interaction are discussed.