Older, hospitalized patients who take diphenhydramine, an often-prescribed antihistamine and sedative, run a 70 percent greater risk of delirium, according to a study by Yale physicians. “The findings suggest that using diphenhydramine as a routine sleeping aid and for most other reasons should be actively discouraged in the older hospitalized population,” said Joseph V. Agostini, M.D., a postdoctoral fellow in the Robert Wood Johnson Clinical Scholars Program, whose findings were published in the September 24 issue of Archives of Internal Medicine. Diphenhydramine is a component of many over-the-counter cold remedies and allergy and insomnia medications such as Benadryl and Sominex.