INTRODUCTION: Incidence of hospitalisations related to psychoactive substance (H-PS) intoxication has been strongly decreased during the coronavirus disease 2019 (COVID-19) pandemic especially in young adult and French region of Nouvelle-Aquitaine was mostly concerned. This study aimed to describe (i) the incidence of H-PS in Bordeaux teaching hospital during and after the first 2020 lockdown in adults aged 18-29 years or 30+ then (ii) their characteristics specifically associated with the pandemic period by comparing 2020 with 2017-2019 baseline period. MATERIAL AND METHODS: This historical cohort study was conducted in adults admitted to the Bordeaux teaching hospital with main or associated diagnosis codes of intoxication with benzodiazepine, methadone, buprenorphine, codeine, morphine, heroin, cocaine, ecstasy and alcohol. Data were collected locally through the discharge database. Incidence and characteristics of H-PS were described according to patients' age, in 2020 before (01/01-16/03), during (17/03-10/05), and after the first lockdown (11/05-31/07). RESULTS: Among the 5,824 stays included over the study period, PS most involved were alcohol and benzodiazepines. Compared to baseline, the decrease in H-PS's incidence was more important in young adults (-40%; n(baseline)=450) in comparison to those aged 30+ (-18%; n(baseline)=1,101) during the pandemic period, especially during the lockdown compared to 2017 (-59%; n(2017)=145 vs. -35%; n(2017)=166) with far decrease in alcohol and ecstasy intoxications. Seriousness of hospitalisation indications was increased regardless of age during the pandemic. Particularly in young adults, the proportion of suicides attempts increased during lockdown compared to the baseline period (almost 50% vs. 29%) and the period after lockdown was associated with 1.7 more-time road accident increased and 3 more-time fights compared with pre-lockdown period. DISCUSSION/CONCLUSION: The period following lockdown should be considered at risk H-PS due to accident. Recreational use of alcohol and ecstasy could be a target for minimize serious consequences associated to PS use in young adult.Read less <