Classic psychedelics such as psilocybin, lysergic acid diethylamide (LSD), and 5-methoxy-dimethyltryptamine (5-MeO-DMT) have shown promising effects in the treatment of certain mental health conditions. Enthusiastic claims about their therapeutic potential have led to overly optimistic reactions in the media and the public, subsequently resulting in increased use outside of clinical contexts and a heightened rate of psychedelic-related complications. As psychedelics exhibit low toxicity and hardly any habit-forming potential, the typical risks and harms of these substances are often overlooked by mental health professionals and under-assessed in psychedelic research. Similar to the medical history of other psychoactive substances introduced as medicines such as opioids, cocaine, and benzodiazepines, awareness for psychedelic-related complications has emerged with delay. Psychedelics are characterized by a wide range of acute effects on the human psyche and by a particular temporal dynamic in which these effects unfold, including acute, subacute, and long-term effects. Knowledge of how psychedelic effects unfold is not only essential for their use in therapy but also for the understanding and management of risks and complications.Here we provide an overview of complications that may be associated with the use of classic psychedelics, drawing on historical and current classification approaches and using the typical temporal dynamics of drug effects as a guiding thread. We will also discuss to what extent psychedelic-related disorders can be causally and specifically attributed to psychedelic use. Finally, considerations regarding the placement of psychedelic-related disorders within nosological-diagnostic classification systems will be discussed. The increasing interest in using psychedelics within the framework of psychotherapy and the rise of non-medical use underscore the need for a more nuanced classification of psychedelic-related risks and harms. The suggested classification can be used as a comprehensive starting point for the assessment of psychedelic-related complications, contributing to maximizing benefits and minimizing risks of these substances in research, therapy, and beyond.
