Co-use of psychedelics with other substances: Findings from the global psychedelic survey.

Background/aims: While most psychedelic substances are considered to carry a relatively low risk of acute or long-term harm, co-use with other psychoactive substances may increase health and social harm. Using a large international survey of adults who use psychedelics, we sought to comprehensively characterize psychedelic co-use.

Methods: We used data from the 2023 Global Psychedelic Survey, a web-based survey of adults ⩾21 with lifetime use of psychedelics. We explored patterns of co-use (prevalence, secondary substances used, timing, and motives of co-use) and examined sociodemographic and psychedelic use-related characteristics associated with co-use overall and by specific psychedelics.

Results: In total, 5370 respondents were included in this analysis, of whom 3228 (56.3%) reported typically co-using at least one of the 11 psychedelic substances of interest, with co-use lowest for ayahuasca (14.8%) and highest for nitrous oxide (54.5%). Cannabis and alcohol were the most common secondary substances. Depressants were the only secondary substance class that increased in use following psychedelic experiences. Greater experience with psychedelics was significantly associated with co-use, as was using for recreational purposes or to reduce/substitute the use of other substances. Personal exploration and therapeutic purposes for psychedelic use were negatively associated with co-use.

Conclusions: In this detailed analysis of psychedelic co-use, we observed high rates of co-use with certain psychedelics, specifically when used recreationally. Our findings highlight psychedelic-specific consumers for whom harm reduction messaging around co-use practices may be best tailored. Further research is justified to assess whether specific patterns of co-use might reduce or increase potential harms.