Background and aimsHallucinogens encompass a diverse range of compounds of increasing scientific and public interest. Risks associated with hallucinogen use are under‐researched and poorly understood. We aimed to compare the trends in hallucinogen‐associated health‐care use with alcohol‐ and cannabis‐associated health‐care use.Design, setting and casesWe conducted an ecological study with publicly available data on International Classification of Diseases, 10th Revision (ICD‐10) diagnosis codes associated with emergency department (ED) visits and hospitalizations from the California Department of Healthcare Access and Information (HCAI). HCAI includes primary and secondary ICD‐10 codes reported with ED or hospital discharge from every non‐federal health‐care facility licensed in California, United States, from 2016 to 2022.MeasurementsICD‐10 codes were classified as hallucinogen‐, cannabis‐ or alcohol‐associated if they were from the corresponding category in the ICD‐10 block ‘mental and behavioral disorders due to psychoactive substance use’.FindingsObserved hallucinogen‐associated ED visits increased by 54% between 2016 and 2022, from 2260 visits to 3476 visits, compared with a 20% decrease in alcohol‐associated ED visits and a 15% increase in cannabis‐associated ED visits. The observed hallucinogen‐associated hospitalizations increased by 55% during the same period, from 2556 to 3965 hospitalizations, compared with a 1% increase in alcohol‐associated hospitalizations and a 1% increase in cannabis‐associated hospitalizations. This rise in hallucinogenic ED visits was significantly different from the trend in cannabis‐associated (P < 0.001) and alcohol‐associated (P = 0.005) ED visits. The hallucinogen‐associated hospitalizations trend also significantly differed when compared with cannabis‐ (P < 0.001) and alcohol‐associated (P < 0.001) hospitalizations.ConclusionsHallucinogen‐associated emergency department visits and hospitalizations in California, USA, showed a large relative but small absolute increase between 2016 and 2022.
