Evaluating the trends and impact of COVID-19 on illicit drug and benzodiazepine use in drivers: A retrospective large-scale study based on oral fluid testing

BACKGROUND: The COVID-19 pandemic disrupted global drug markets, but consumption soon returned to pre-pandemic levels. Continuous monitoring of drug use trends is essential for effective public health responses. METHODS: A total of 29,397 oral fluid specimens from roadside drug tests across Spain (January 2019-July 2024) were sent to the Toxicology Laboratory of the Institute of Forensic Sciences, University of Santiago de Compostela, for LC-MS/MS confirmation of on-site positives. Results were stratified into five periods to assess drug use trends and the impact of COVID-19. RESULTS: Over 90% of drivers were male, and 85% were under 45 years old. Overall, 69.9% of samples were positive for cannabis, 64.9% for cocaine, 13.7% for amphetamines, 10.6% for opiates, 6.5% for ketamine, 5.4% for methadone and 6.6% for benzodiazepines/zolpidem; 56.3% showed poly-drug use. Cannabis use was higher in men, while amphetamines and benzodiazepines were more frequent in women (p < 0.001). Due to regional variability in drug use patterns and sample distribution, trends were analyzed across five geographic regions. Globally, during the strict lockdown, cocaine, opiates, methadone and benzodiazepines peaked, while cannabis and amphetamines declined, and ketamine remained stable. In the final period, cannabis reached its highest levels, and ketamine showed a marked increase. Cocaine and amphetamines returned to pre-COVID levels, while opiates, methadone and benzodiazepines declined. Statistically significant differences across the studied periods were observed in the different regions. Specifically, in the Northwest for opiates, methadone, and benzodiazepines (p < 0.001), as well as for cannabis (p < 0.05); in the East for opiates, amphetamines, cocaine, and ketamine (p < 0.001); in the Center for cocaine (p < 0.001) and ketamine (p < 0.05); and in the South and Islands for cocaine (p < 0.05). CONCLUSIONS: Although a slight impact on drug use was observed during the strict lockdown, consumption increased again for all substances (particularly ketamine), except for opiates, methadone and benzodiazepines.