Because of this, hyperthermia, or overheating, can occur in certain settings, such as clubs where people may dance for hours in a hot environment without taking breaks or drinking water, said Matthias Liechti, a professor of clinical pharmacology at the University Hospital of Basel in Switzerland. Signs of hyperthermia include redness, shivering and a lack of sweating, as well as disorientation. The risk of overheating increases if someone consumes too much MDMA, or if it is mixed it with alcohol or other drugs, Dr. Baggott said.
Another rarer but also potentially deadly problem is overhydrating. This typically occurs when an MDMA user becomes overly concerned about becoming dehydrated, Dr. Johnson said, and starts drinking water “obsessively to counteract that.”
MDMA causes fluid retention, so drinking too much water can lead to hyponatremia, or below-normal blood sodium levels. This, in turn, can cause cerebral edema, a potentially fatal condition in which brain cells swell. Hyponatremia in MDMA users is more likely to occur in women because of additional natural hormonal effects. A 2013 review found 25 reports of Ecstasy-related hyponatremia, almost all of which occurred in women between the ages of 15 to 30, and over half of which were fatal.
There is no consensus on how much water is too much, Dr. Baggott said, but based on research he published in 2016, a dangerous amount could be “about half gallon, if drunk quickly.”
To avoid such problems, users should “drink a bunch of water a few hours before they plan to take MDMA so they start out well-hydrated,” he said. Because MDMA itself doesn’t cause dehydration, once taken, a user would not need extra fluid, he added, only enough to replace what is lost from sweating or vomiting, which sometimes occurs.
