MDMA & sex. Mdma combines amphetamine and mescaline-type hallucinogenic effects. It increases release of serotonin, dopamine, and norepinephrine -- with increased energy, euphoria, and increased closeness and empathy plus distortions in sensory and time perception. Serotonin also causes release of oxytocin & vasopressin -- leading to increase in sexual arousal. Ability to act on this may be affected, though.