The subacute period following the use of classic psychedelics is often marked by an "afterglow" - a state characterized by elevated mood; enhanced psychological well-being; increased emotional openness toward self, others, and nature; and sometimes a heightened sense of clarity and existential meaning. From a neurobiological perspective, subacute psychedelic states have been associated with changes in brain network connectivity, amygdala reactivity, and neuroplasticity.However, individual responses to psychedelics vary considerably, and not all users experience positive aftereffects. Some struggle to make sense of their psychedelic experiences or to integrate them into daily life. Others report psychological instability, including mood swings, anxiety, panic attacks, sleep disturbances, depressive symptoms, feelings of alienation, depersonalization, derealization, persisting perceptual changes, flashbacks, prolonged psychosis, mania, or suicidal ideation.Many of these issues can be mitigated through interventions commonly referred to as "psychedelic integration," often practiced individually or provided by peers within the psychedelic community or through other forms of social support. In cases of severe or persistent symptoms, however, professional mental health care may be required. Key components in managing subacute complications include establishing safety, mobilizing internal and external resources, supporting the psychological processing of the experience, addressing maladaptive interpretations, monitoring symptom progression, and, when indicated, pharmacotherapy. Persistent complications may furthermore warrant established disorder-specific treatment to prevent further chronification.This chapter outlines and discusses strategies for managing clinically significant subacute complications, with the aim of advancing a nuanced harm-reduction framework relevant to research, clinical, and non-clinical contexts.
