The physical effects of usual doses of MDMA usually begin with a light sickness feeling and thirst, jaw clenching, teeth grinding, rapid eye movements, sweating, or nausea. Others report feelings of profound physical relaxation. After 30 minutes the euphoria occurs. Typical sought-after psychological effects include feeling "at peace" or experiencing a generalized "happy" feeling, and emotional closeness to oneself and others. MDMA can significantly enhance and distort the senses of touch, vision (contours of things and persons fade and are colored), taste, and smell. But for others, or even the same person at different times, the hallucinations can be scary and produce feelings of anxiety. Under moderate doses the user seldom loses complete control of the situation.
At higher doses, MDMA can produce physical effects resembling amphetamine, including fast or pounding heartbeat, sweating, dizziness, restlessness. MDMA overdose can also occur - the symptoms can include high blood pressure, faintness, panic attacks, and in severe cases, a loss of consciousness, and seizures.
Because of its stimulant properties and the environment in which it is often taken, MDMA is associated with vigorous physical activity for extended periods, typically associated with “raves”. This can lead to one of the most significant, although rare, acute adverse effects -- a marked rise in body temperature (hyperthermia). Treatment of hyperthermia requires prompt medical attention, as it can rapidly lead to muscle breakdown, which can in turn result in kidney failure. In addition, dehydration, hypertension, and heart failure may occur in susceptible individuals. MDMA can also reduce the pumping efficiency of the heart, of particular concern during periods of increased physical activity, thereby further complicating these problems. MDMA abusers are particularly vulnerable to overdose due to poor judgment caused by the drug combined with a desire to extend the sought-after effects. In addition, MDMA interferes chemically with its breakdown within the body, further increasing the possibility of overdose.
Over the course of the week following moderate use of the drug, many MDMA users report feeling a range of emotions, including anxiety, restlessness, irritability, and sadness that in some individuals can be as severe as true clinical depression. Similarly, elevated anxiety, impulsiveness, and aggression, as well as sleep disturbances, lack of appetite and reduced interest in and pleasure from sex have been observed in regular MDMA users. Some of these disturbances may not be directly attributable to MDMA, but may be related to some of the other drugs often used in combination with MDMA, such as cocaine or marijuana, or other drugs contained in the MDMA tablet itself, such as methamphetamine.