Background and aims: In recent years, the potency of natural cannabis products (herb and resin) has increased with a higher delta- 9-tetrahydrocannabinol (Δ9-THC) content, but there are limited data on trends on clinical presentation and severity of toxicity in cannabis users consulting the emergency department (ED) for acute intoxication. This study aimed to analyse the evolution over time of clinical findings and severity of presentations in a large series of patients presenting to European EDs with acute toxicity after lone cannabis use.

Design: Secondary analysis of data included in the Euro-DEN Registry from 1 October 2013 to 31 December 2022.

Setting: 40 EDs in 25 European countries.

Participants/cases: ED presentations reporting lone cannabis use. Presentations reporting concomitant use of, or having positive toxicological tests for, ethanol or other drugs were excluded. 3839 ED presentations reporting lone cannabis use were analysed (median age 25 years, interquartile range= 20-33; 71% male).

Measurements: Temporal trends of 14 pre-defined clinical signs/symptoms and 4 markers of severity, which included the need for ambulance transfer to the ED, hospitalisation, intensive care unit admission (ICU) and death.

Findings: The most frequent clinical features were anxiety (35%), agitation (22%), decreased alertness (drowsiness or coma, 21%) and vomiting (20%), while seizures, arrythmias and hyperthermia were observed in <3% of cases. Statistically significant changes over time were only found in the frequency of hypotension [adjusted odds ratio (OR) = 1.239 per every subsequent year, 95% confidence interval (CI) = 1.107-1.386], hypertensive crisis (OR = 1.168, 95% CI = 1.070-1.274) and palpitations (OR = 0.922, 95% CI = 0.883-0.962). Nonlinear analyses detected statistically significant mid-period increases for anxiety, agitation and arrhythmias that subsided by the end of the study, and showed increases in chest pain and decreases in seizures that became statistically significant in the latter half of the period. Regarding episode severity, 76% of cases were brought to the ED by ambulance, 13% required hospitalisation, 1% were admitted to the ICU and 0.1% died. No statistically significant changes were observed over time in either the linear or the nonlinear models.

Conclusion: Very few changes in the clinical features of patients presenting to European emergency departments with lone acute cannabis toxicity were identified over 2013 to 2022, suggesting that despite the increase in potency of cannabis in Europe over this period, the severity of acute intoxication has remained unchanged.