"Hall and Henry (2006) reviewed the medical scenarios and treatment options for physicians dealing with MDMA-related medical emergencies: ‘Hyperpyrexia and multi-organ failure are now relatively well-known, other serious effects have become apparent more recently. Patients with acute MDMA toxicity may present to doctors working in Anaesthesia, Intensive Care, and Emergency Medicine. A broad knowledge of these pathologies and their treatment is necessary for those working in an acute medicine speciality’.

"Despite rapid medical intervention, some disorders are difficult to reverse and deteriorate rapidly, with occasional fatal outcomes (Schifano et al., 2003). In an early report, Henry et al. (1992) described MDMA-induced fatalities in seven young party goers, whose body temperatures at the intensive care unit ranged between 40 C and 43 C. The causes of death include various forms of organ failure. MDMA induces apoptosis, or programmed cell death, in cultured liver cells (Montiel-Duarte et al., 2002), and another form of death is from acute liver failure (Smith et al., 2005). Other fatalities result from cardiac arrest, brain seizure, ‘rhabdomyolysis’ or the destruction of skeletal muscle tissue, and ‘disseminated intravascular coagulation’ or the failure of blood clotting—which results in uncontrollable bleeding through multiple sites (Henry et al., 1992; Hall and Henry, 2006)."

Source

Parrott, Andrew C., "Human Psychobiology of MDMA or 'Ecstasy': An Overview of 25 Years of Empirical Research," Human Psychopharmacology: Clinical and Experimental, 2013; 28:289-307. DOI: 10.1002/hup.2318