First-generation antihistamines increase the risk of delirium in older hospitalized patients.

First-generation antihistamines increase the risk of delirium in older hospitalized patients.

Risks of antihistamines in older patients

An analysis inJournal of the American Geriatrics Societyshows that older patients hospitalized and cared for by physicians who prescribe high levels of first-generation antihistamines are at increased risk of delirium.

What are first generation antihistamines?

Antihistamines are medications primarily used to treat allergies. However, the first generation, such as diphenhydramine (known as Benadryl), can also cause drowsiness. This is particularly problematic for older people, who may become further confused or disoriented by this effect.

The study in detail

A study analyzed data from 328,140 patients aged 65 and over who were treated at 17 hospitals in Ontario, Canada, between 2015 and 2022. The patients were cared for by 755 doctors. The results showed that 34.8% of patients developed delirium.

Patients who went to doctors who frequently prescribed first-generation antihistamines were 41% more likely to experience delirium compared to patients who went to doctors who rarely prescribed these medications.

Important message

“We hope our study will raise awareness among hospital physicians that sedating antihistamines can be harmful and should be prescribed cautiously.”

Aaron M. Drucker, MD, lead author, University of Toronto and Women's College Hospital

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