A cross-national comparison of nonmedical and medical use of psychedelic drugs in the international cannabis policy study.
Myfanwy Graham, Yimin Ge, Rosalie Liccardo Pacula, Seema Choksy Pessar, Chris Wilkins, Wayne Hall, David Hammond
International Journal of Drug Policy August 1, 2026 DOI: 10.1016/j.drugpo.2026.105348 (opens in new tab)
Study at a glance
AI-extracted from the abstract| Characteristics | Repeated cross-sectional survey Peer reviewed |
|---|---|
| Population | Adults in Canada, the United States, Australia, and New Zealand |
| Topics | Cannabis |
| Keywords | Adverse events Drug policy Nonmedical use Psychedelics |
| Citations | 1 |
| Key findings | An estimated 19% of respondents reported lifetime use of psilocybin, LSD, MDMA, or ketamine, with psilocybin being the most commonly used substance, and over a third of past-year users reported experiencing an adverse health effect. |
Abstract
We know little about the extent psychedelic substances are consumed therapeutically and/or discussed with medical professionals despite renewed global interest in these substances. We examined self-reported responses from the 2023 International Cannabis Policy Study (ICPS) in repeated cross-sectional surveys in Canada, the United States, Australia, and New Zealand. The survey included questions on lifetime, past year, and past month use of psilocybin, LSD, MDMA, and ketamine. It inquired about respondents' discussions with medical professionals, their self-reported medical use, and related adverse events. We estimate the mean proportion rate for each of these using logistic regression methods that adjust for demographics, country, and sampling weights. Estimated results suggest nineteen per cent of all ICPS respondents reported lifetime use of one of the four substances. Psilocybin was the most commonly estimated to be used in one's lifetime and in the past year, followed by LSD and MDMA. Estimated prevalences of ever using psilocybin were higher among respondents from Canada (16.3%, CI: 15.6-16.9%) than the USA (13.0%, CI: 12.3-13.6%) and New Zealand (12.1%, CI: 10.4-13.8%). Estimated rates of psilocybin ever use in Australia were significantly lower (7.8%, CI: 6.8-8.8%). An estimated 10-20% of respondents who report ever-use of a psychedelic asked their medical provider about medical use, and over a third who had used in the past year reported experiencing an adverse health effect. Estimated rates of past month use were low for all countries. Consumer interest in therapeutic use of psilocybin, MDMA, LSD, and ketamine has surpassed the pace of clinical trials and therapeutic use provisions. These provisions do not necessarily equate to patient access and dual use motivations are not uncommon. Access via nonregulated pathways and self-initiated use in the absence of medical supervision may influence the proportion of individuals who experience adverse events.
Comparable studies
Other cross-sectional and survey studies on cannabis, most cited first.
| Study | Year | Design | Participants |
|---|---|---|---|
| Cannabis use before age 15 and subsequent executive functioning 104 chronic cannabis users (49 early-onset before age 15, 55 late-onset after age 15)... | 2011 | Observational cross-sectional study | n = 148 |
| Patterns of simultaneous polysubstance use in drug using university students Drug-using university students | 2006 | Cross-sectional survey | n = 149 |
| Persisting Reductions in Cannabis, Opioid, and Stimulant Misuse After Naturalistic Psychedelic Use: An Online Survey Online survey respondents | 2020 | Cross-sectional survey | |
| User perceptions of the benefits and harms of hallucinogenic drug use: A web-based questionnaire study Users of hallucinogenic drugs who completed a web-based questionnaire | 2010 | Cross-sectional survey | n = 600 |
| Illicit Use of LSD or Psilocybin, but not MDMA or Nonpsychedelic Drugs, is Associated with Mystical Experiences in a Dose-Dependent Manner Adults recruited from the MAPS website and newsletter, most reporting use of various... | 2012 | Cross-sectional survey | n = 337 |
Citations in the library
Cites 11
- Adverse events in clinical treatments with serotonergic psychedelics and MDMA: A mixed-methods systematic review Journal of Psychopharmacology August 26, 2022
- Extended difficulties following the use of psychedelic drugs: A mixed methods study PLoS One October 24, 2023
- Adverse Events in Studies of Classic Psychedelics JAMA Psychiatry September 4, 2024
- The Global Psychedelic Survey: Consumer characteristics, patterns of use, and access in primarily anglophone regions around the world. International Journal of Drug Policy August 1, 2024
- The Canadian Psychedelic Survey: Characteristics, Patterns of Use, and Access in a Large Sample of People Who Use Psychedelic Drugs. Psychedelic Medicine June 1, 2023
and 6 more in the library