Acute Effects
A person may experience the intoxicating effects of MDMA within 45 minutes or so after taking a single dose. Those effects include an enhanced sense of well-being,28,53 increased extroversion,27,53 emotional warmth, empathy toward others,54 and a willingness to discuss emotionally-charged memories.55 In addition, people report enhanced sensory perception as a hallmark of the MDMA experience.27,28
However, MDMA can also cause a number of acute adverse health effects. For example, while fatal overdoses on MDMA are rare, they can potentially be life threatening—with symptoms including high blood pressure (hypertension), faintness,8,56 panic attacks,57 and in severe cases, a loss of consciousness and seizures.58
Because of its stimulant properties and the situations in which it is often taken, MDMA is associated with vigorous physical activity for extended periods in warm environments. This can lead to one of the most significant, although rare, acute adverse effects—a marked rise in body temperature (hyperthermia).59–61 Research in rats shows that even moderate doses of MDMA interfere with the body’s ability to regulate temperature, potentially leading to deadly consequences in warm environments.6 Treatment of hyperthermia requires prompt medical attention, as it can rapidly lead to muscle breakdown or an electrolyte (sodium) imbalance, which can in turn produce kidney failure9 or fatal swelling of the brain, especially in women.62 MDMA use in combination with vigorous exercise causes dehydration,56,57 leading some people to drink large amounts of liquids. However, this could increase the risk of electrolyte imbalance or brain swelling because MDMA causes the body to retain water.63,64 One modest dose of MDMA can also reduce the pumping efficiency of the heart in people who use regularly,65 which is of particular concern during periods of increased physical activity.
MDMA can also produce other adverse health effects, including involuntary jaw clenching,53 lack of appetite,28,53 mild detachment from oneself (depersonalization), illogical or disorganized thoughts, restless legs,28 nausea,56,57,66 hot flashes or chills,8,56 headache, sweating,8,57 and muscle or joint stiffness.66
In the hours after taking the drug, MDMA produces significant reductions in perceiving and predicting motion—for example, the ability to judge whether a driver is in danger of colliding with another car. This emphasizes the potential dangers of performing complex or skilled activities, such as driving a car, while under the influence of this drug.67
Once MDMA is metabolized, or broken down in the body, its byproducts interfere with the body's ability to metabolize MDMA.68 As a result, additional doses of MDMA can produce unexpectedly high blood levels, which could worsen the toxic effects of this drug.69 In addition, combining MDMA with other substances, such as caffeine,70 amphetamines,71 the amphetamine-like mephedrone,72 marijuana,73 or alcohol,74,75 may increase the risk of adverse health effects associated with MDMA.29
Sub-acute Effects
Recreational use of MDMA is often characterized by repeated drug taking over a number of days (binges), followed by periods of no drug taking. In one animal study, this pattern of use produced irregular heartbeat (arrhythmia) and heart damage.76 In the week following use of the drug, many people report depression, impaired attention and memory,77–79 anxiety, aggression,80 and irritability.78
Effects of Regular MDMA Use
Sleep disturbances, lack of appetite, concentration difficulties, depression,79 heart disease,81,82 and impulsivity83 have been associated with regular use of MDMA. In addition, heavy MDMA use over a 2-year period of time is associated with decreased cognitive function.84 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, alcohol, or marijuana, or to adulterants commonly found in MDMA tablets. More research is needed to understand the specific effects of regular MDMA use.
Risk-taking in People who Use MDMA
Various studies have found that MDMA use is associated with risky sexual behaviors. For example, both males and females who use MDMA are more likely than alcohol-drinking controls to engage in risky sexual behaviors (e.g., without a condom).85 MDMA use within the past 6 months is associated with initiating sex before age 14 and having two or more partners in the past 2 months.86 In addition, people who use heavily report more sexual risk taking than those who use less often. People who use heavily are also more likely to have been tested for HIV, though they believe they are at low risk for contracting the disease.87
Homosexuals and bisexuals who use MDMA, both male and female, reported more sexual partners and more injection drug use—but did not have higher rates of unprotected sex and needle sharing—compared to heterosexuals who use MDMA.88