Diphenhydramine Use and Dementia Risk

Evidence from Guidelines

The American Geriatrics Society (AGS) recommends avoiding diphenhydramine in older adults due to its highly anticholinergic properties, which increase the risk of cognitive impairment, confusion, and delirium 1
The AGS classifies diphenhydramine as having "high anticholinergic properties" that should be avoided in older adults due to substantial CNS effects 1
The AGS postoperative delirium guideline specifically identifies diphenhydramine among medications that induce delirium and should be avoided in older surgical patients 2

For sleep disturbances, the American Academy of Sleep Medicine recommends avoiding diphenhydramine entirely and considering melatonin or behavioral interventions instead 3
For allergic reactions, short-term use of diphenhydramine may be justified, but chronic use should be avoided 2
For patients already taking diphenhydramine, the AGS recommends discontinuing it if possible and switching to non-anticholinergic alternatives 1

The American Academy of Sleep Medicine warns against assuming over-the-counter status means safety, as diphenhydramine's widespread availability as an OTC sleep aid does not negate its significant cognitive risks in older adults 3
The American Academy of Sleep Medicine advises against using diphenhydramine for chronic insomnia, as there is virtually no evidence-based data to support its efficacy for sleep in older adults, while risks are substantial 3

Diphenhydramine is classified as a strongly anticholinergic medication that is poorly tolerated in older patients and those with Parkinson's disease, causing broad muscarinic receptor blockade, resulting in negative effects on vision, urination, constipation, and cognition 4
Patients taking anticholinergic drugs experience "anticholinergic burden" that adversely affects cognition, functional status, and activities of daily living (ADL) scores 4
The American Geriatrics Society recommends that anticholinergic medications should be used with caution in older adults due to their CNS effects, as seen with diphenhydramine 5

For psychosis in Parkinson's disease patients, the American Academy of Neurology recommends quetiapine, clozapine, or pimavanserin as alternatives to anticholinergic agents 6
For cognitive decline with psychosis, the European Federation of Neurological Societies suggests that rivastigmine, a cholinesterase inhibitor, may be considered 7