Recreational doses of MDMA (50 to 150 mg) in healthy volunteers cause pupil dilation, increases in systolic and diastolic blood pressure, heart rate, and pupillary diameter. Oral temperature changes are biphasic: a slight decrease at 1 hour followed by increases at 2 and 4 hours. Psychomotor performance shows slight dose-dependent impairment. Plasma cortisol and prolactin concentrations rise markedly. The drug's elimination half-life is about 8-9 hours. Peak drug concentrations and physiological effects occur between 1 and 2 hours and return to baseline 4-6 hours after administration.
Repeated use of MDMA ('ecstasy') causes time-dependent immune dysfunction similar to a single dose, but the second dose extends the period of impaired immunocompetence. The drug decreases CD4 T-helper cells, increases natural killer (NK) cells, and reduces lymphocyte responsiveness to stimulation. In poor metabolizers, MDMA accumulation produces greater immunomodulatory effects, including significant differences in NK cell function. Recreational MDMA users show long-term alterations: reduced lymphocytes, T cells, and CD4 cells (though within normal limits), and NK cells reduced to one-third of healthy levels. Over two years, a subgroup showed statistically significant decreases in immune parameters, potentially increasing susceptibility to infection and immune disorders.