MDMA given at recreational doses (range tested 50 to 150 mg) to healthy volunteers, produced mydriasis and marked increases in systolic and diastolic blood pressure, heart rate, and pupillary diameter. MDMA induced changes on oral temperature. The time course of this observation was biphasic, as a slight decrease at 1 h and a slight increase at 2 and 4 h were observed. MDMA induced a slight dose-dependent impairment on psychomotor performance. MDMA produced a marked rise in plasma cortisol and prolactin concentrations. The elimination half-life of MDMA was about 8-9 h. Drug concentrations increased, and a parallel increase in physiologic and hormonal measures was observed. Both peak concentrations and peak effects were obtained between 1 and 2 h and decreased to baseline values 4-6 h after drug administration.