Introduction and Aims: Emerging psychoactive substances (EPS) are relatively new substances that have not been formally studied or are still being researched. As such, little is known about the effects and risks of these drugs and there have been few animal or human toxicology studies examining issues such as acute adverse events, drug interactions, long-term health impacts or addiction.

Design and Methods: Frequent ecstasy psychostimulant users interviewed for the Ecstasy and Related Drugs Reporting System in 2012 and 2013 (n∼1208) provided subjective ratings on substances consumed in the last six months. Participants rated the pleasurable and negative (acute and longer-term) effects of each drug on the last occasion of use and the likelihood of future use.

Results: Stimulant EPS (mephedrone, methylone, methylenedioxypyrovalerone) were rated less favourably than ecstasy and cocaine in terms of pleasurable effects and likelihood of future use. Dimethyltryptamine (DMT) showed a similar profile to LSD in terms of the pleasurable effects and the likelihood of future use, but negative (acute and hangover) effects were rated as lower. 2CB showed a similar profile to LSD in terms of negative effects but was rated as less pleasurable and less likely to be used again.

Discussion and Conclusions: The results suggest that the abuse potential of EPS stimulants may be lower compared to commonly used stimulants such as ecstasy and cocaine. In contrast, the abuse potential of DMT may be higher relative to LSD given the relative absence of negative effects. These findings have important implications for understanding the use and abuse potential of EPS.