Study Links Sedating Antihistamine Prescribing to Higher Delirium Risk in Older Hospital Patients

Overview

• Older adults admitted to physicians who frequently prescribed first‑generation antihistamines had 41% higher odds of in‑hospital delirium than those admitted to low‑prescribing physicians.
• The analysis covered 328,140 patients aged 65 and older treated by 755 attending physicians across 17 Ontario hospitals from 2015 to 2022.
• Delirium occurred in 34.8% of the cohort, underscoring its common and serious impact during hospitalization for older patients.
• First‑generation agents such as diphenhydramine are sedating and anticholinergic, are linked to medication‑related harms, and may be used inappropriately when non‑sedating alternatives exist.
• Findings are observational and do not prove causation, and the peer‑reviewed study was published October 22, 2025 in the Journal of the American Geriatrics Society (DOI: 10.1111/jgs.70121), with Aaron M. Drucker, MD, as corresponding author.