INTRODUCTION: The persistent increase in the use of 3,4-methylenedioxymetamfetamine has led to an increase in emergency department presentations. Our aim was to study the most frequent reasons for admission to the intensive care unit of critically ill patients with 3,4-methylenedioxymetamfetamine intoxication and to describe their complications, management and outcome. METHODS: This retrospective cohort study included all patients with confirmed or self-reported 3,4-methylenedioxymetamfetamine intoxication admitted to the intensive care of a tertiary care hospital in Amsterdam between 2010 and 2020. RESULTS: Seventy-four patients (73% male) were included. Three patients (4%) died. The most common reason for intensive care admission was a threatened airway ( DISCUSSION: Unlike other studies, trismus was the most common reason for intensive care unit admission in our study. Trismus, or its treatment with benzodiazepines, may lead to respiratory acidosis. The median correction of the serum sodium concentration in our population was greater than advised in the European guideline. The occurrence of osmotic demyelination was not reported. CONCLUSION: The three most common complications of 3,4-methylenedioxymetamfetamine use necessitating intensive care admission were a threatened airway due to trismus, hyponatraemia and hyperthermia. Severe complications can arise, especially in patients presenting with hyperthermia. Although the majority of patients included in this study made a full recovery, 4% died.