Addictovigilance is a French health monitoring system, composed of 13 centres distributed across the national territory, that aims to monitor cases of abuse, misuse, or use disorders related to psychoactive substances. Fulfilling these missions requires a regional network that ensures efficient information flow, dissemination to health authorities, and subsequent downward communication to prevent risks. This was illustrated through the example of nitrous oxide misuse. The Nantes Addictovigilance Centre, which is responsible for nitrous oxide monitoring, has highlighted the emergence of a signal from the very first cases. Since 2018, 6 national addictovigilance reports have subsequently been produced highlighting the increase in this signal in quantitative terms and in qualitative terms, with a diversification and worsening of complications (use disorders, neurological, psychiatric, cardiac and more recently thromboembolic). At the local and regional level, each addictovigilance centre has relayed information to its network, in a variety of ways, but also to the general public, particularly through the media. Studies have also been carried out to better quantify and qualify nitrous oxide consumption. These signals from addictovigilance data have been the subject of numerous national and international communications (health authorities, addictovigilance network, international scientific articles). They have also contributed to the promulgation of the French law of June 2021 aimed to prevent dangerous uses of nitrous oxide, and international reporting. The addictovigilance centres have made it possible to obtain an early, rapid and accurate signal with pharmacological and medical data. Nitrous oxide is an example of the wide potential of action of the French addictovigilance network, in all its fields of competence: training, specific collection, research and information. [Author's abstract]