Cannabis Withdrawal May Trigger Psychiatric Crises 3-5 Days After Hospital Admission

Among 52,088 psychiatric admissions in London over 16 years, cannabis users were 44% more likely than non-users to require psychiatric intensive care overall. During the specific 3-5 day post-admission window when cannabis withdrawal peaks, transfers to intensive care were more common in cannabis users (31.0%) than non-users (24.2%). The association was strongest in women (2x the odds) and adults over 35 (2.5x the odds).

Retrospective cohort study using electronic health records from four psychiatric hospitals in London (2008-2023). Cannabis use status was determined through natural language processing of clinical records combined with manual review. Multivariable models adjusted for age, gender, ethnicity, diagnosis, tobacco use, stimulant use, and comorbid substance use disorders.

Cannabis withdrawal is often overlooked in psychiatric settings. This study provides evidence that forced abstinence during hospitalization may trigger a predictable worsening of psychiatric symptoms during the withdrawal peak window, potentially leading to unnecessary escalation of care.

If cannabis withdrawal is causing predictable psychiatric deterioration in the first week of admission, hospitals could potentially plan for it with targeted interventions during the withdrawal window rather than reactive transfers to intensive care.

Cannabis use was identified from clinical records, which may undercount actual users. The study cannot definitively prove that withdrawal caused the transfers rather than other factors associated with cannabis use. The London population may not be representative of all psychiatric settings.