Natural cannabis has been used throughout history since antiquity; nowadays it is one of the most widely used recreational illicit drugs throughout the world, and its abuse showed recent increases, especially among young people. Cannabnoids are complex and still poorly known substances with many different effects and functions.
The acute psychological effects due to the main psychoactive constituent (Δ-9-tetrahydrocannabinol) are well described; its connection to chronic psychiatric and cognitive aspects, immunological and hormonal functions, and social problems is much less defined. Phytocannabinoids have a narrow range between desired effectiveness and unwanted or adverse consequences.
Laboratory screening procedures have not demonstrated to be useful to define acute intoxication: this specific diagnosis is mainly based on a clinical ground, and it is often impossible to clearly differentiate signs and symptoms due to the underlying co-occurring use of other known or emerging recreational psychoactive drugs of abuse in combination, with or without the user’s knowledge.
Regular use of cannabis may lead to dependency and to a mild withdrawal syndrome. Acute complications and drug-related Emergency Department episodes (notably intoxication, psychotic states and panic attacks) are rare, and can be usually managed with a period of observation and treated with conservative measures.
The aim of the present review is to provide a contemporary overview of the main characteristics of natural cannabinoid agonists and analogues, with special emphasis on the pharmacodynamic aspects, to facilitate the understanding of the psychotropic activity and effects, and to highlight the approach to effective management for the Emergency Physician.