New Delhi, Oct 22 (IANS) — A new study has warned that certain antihistamines, commonly used as anti-allergy medications, may raise the risk of dementia-related complications in elderly patients.
Dementia currently affects over 57.4 million people worldwide, a figure projected to nearly triple to 152.8 million by 2050. Early signs include memory loss, confusion, difficulty finding words, and changes in mood or behaviour.
Published in the Journal of the American Geriatrics Society, the study found that older inpatients treated by physicians who frequently prescribe first-generation antihistamines—such as diphenhydramine—face an elevated risk of developing delirium, a sudden and severe state of confusion, during hospital stays.
Researchers from the University of Toronto analysed data from 328,140 patients aged 65 and above, admitted to 17 hospitals in Ontario, Canada, between 2015 and 2022. They discovered that patients admitted under physicians who commonly prescribed first-generation antihistamines had 41% higher odds of experiencing delirium compared with those admitted under physicians who rarely prescribed these drugs. Overall, delirium was observed in 34.8% of cases.
“First-generation antihistamines are among the leading causes of medication-related harms in older adults,” said corresponding author Aaron M. Drucker. “While these medications are indicated for conditions such as hives and anaphylaxis, they are often prescribed inappropriately.”
The study emphasised that first-generation antihistamines provide no added benefit over non-sedating alternatives, which are safer and associated with fewer adverse effects. Delirium in older adults has been linked to long-term cognitive decline and higher mortality.
The researchers urged hospitalists to exercise caution when prescribing sedating antihistamines to elderly patients.
