Older patients face challenges during hospitalization including fear, loneliness, stress, and isolation and may even experience a decline in mental acuity.

New research has taken more of a deeper dive into the mental reaction of inpatients.

A recent analysis in the Journal of the American Geriatrics Society demonstrated how older inpatients “admitted to physicians who prescribe higher amounts of first-generation antihistamines faced an elevated risk of delirium while in the hospital.” 

The research revealed that first-generation antihistamines, like diphenhydramine (Benadryl), are among the leading causes of medication-related risks in older adults. Also, older patients are frequently prescribed antihistamines for such things as anaphylaxis or hives. The paper revealed these medications could be inappropriately prescribed to this patient population.

Aaron Drucker, MD, associate professor, University of Toronto, Toronto, Ontario, Canada, the senior author of the research, said clinicians should understand the elevated risks and be mindful of possible signs of delirium while hospitalized. He offered these data directives: 

• Be aware that increased prescribing of sedating antihistamines in hospital could increase the risk for delirium.
• Consider whether sedating antihistamines are truly indicated before prescribing them to older inpatients.
• Recognize delirium risk is elevated for inpatients. “Delirium is common in hospitalizations, particularly for older adults,” said Drucker. “Severe illness, being in a new environment, difficulty sleeping and being prescribed new medications can all predispose to delirium.”

How Was the Study Conducted?

When investigators analyzed data on 328,140 patients aged 65 years or older who were admitted by 755 attending physicians to 17 hospitals in Ontario, Canada, in 2015-2022, they found the overall prevalence of delirium was 34.8%.

“Patients admitted to physicians who more commonly prescribed first-generation antihistamines had 41% increased odds of experiencing delirium compared with patients admitted to physicians who rarely prescribed first-generation antihistamines,” the authors wrote.

“Because what doctor patients are assigned to when they are admitted is random, this suggests that the sedating antihistamine prescribing may be driving that association,” Drucker said. “The message of our paper is more about decreasing the use of these medications that can be harmful.”

Drucker said the analysis showed that prescribing histamines to older hospitalized patients should be carefully considered.

“Most of the time, sedating antihistamines aren’t needed during hospital admissions,” Drucker continued. “Whenever they can be avoided, they should be their prescribing practices, particularly where elderly patients are in question.”