Flashbacks Through Time: Historical Development and Current Use of the Term “Flashback” in Psychedelic and Post‐Traumatic Stress Disorder Research

In psychiatry, the term flashback is widely recognized in relation to post-traumatic stress disorder (PTSD) as well as in the characterization of post-psychedelic experiences. Although it is now most commonly associated with PTSD, the term was originally introduced in the context of psychedelics. While it broadly denotes specific forms of re-experiencing in both fields, its precise meaning differs significantly between them. In PTSD, flashbacks refer to intrusive, vivid memories with a pronounced "here-and-now" quality. In psychedelic research, however, the term flashback does not function as a clearly defined symptom but rather as an umbrella term encompassing multiple similar yet distinct forms of post-acute psychedelic experiences that potentially arise from different causal mechanisms. This terminological ambiguity complicates systematic investigation and precise clinical understanding of post-psychedelic symptoms, ultimately limiting effective care for affected individuals. As research into the classification and treatment of post-psychedelic difficulties advances, the development of a more differentiated and clearly defined vocabulary is needed. Greater conceptual clarity would facilitate improved scientific communication, more targeted research, and better clinical care for individuals navigating the often complex aftermath of psychedelic experiences.