The Hidden Risk of Benadryl for Seniors: What Every Alzheimer’s Caregiver Should Know

Written by Nguyenjessica

Published on July 24 2025

In the U.S., over-the-counter medications like Benadryl (diphenhydramine) are often considered safe staples in every household. Used for allergies, sleep problems, or the common cold, it’s easy to assume that if it's on the shelf at CVS or Walgreens, it's harmless—especially for older adults. But when it comes to seniors, and particularly those living with Alzheimer’s disease or other dementias, Benadryl may do more harm than good.

This article will explore the science behind Benadryl’s effects on the aging brain, highlight warnings from U.S. medical associations, and help caregivers make safer decisions for their loved ones.

The Hidden Risk of Benadryl for Seniors: What Every Alzheimer’s Caregiver Should Know

Key Points

Benadryl (diphenhydramine) is an anticholinergic drug that can impair brain function, especially in older adults.

Studies in the U.S. have linked long-term use of anticholinergic medications with increased dementia risk.

The Beers Criteria, developed by the American Geriatrics Society, recommends avoiding diphenhydramine in people 65 and older.

Side effects in elderly patients include confusion, memory loss, hallucinations, and increased fall risk.

Safer alternatives and physician guidance are critical for those caring for someone with Alzheimer’s.

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Table of content

What Is Benadryl and Why Is It So Common in the U.S.?

How Benadryl Affects the Aging Brain?

Alzheimer’s and Anticholinergic Drugs: A Dangerous Combination

Safer Alternatives for Allergies and Sleep in Seniors

Tips for Caregivers and Families in the U.S. Healthcare System

What Is Benadryl and Why Is It So Common in the U.S.?

Benadryl, with its active ingredient diphenhydramine, is a first-generation antihistamine. In the United States, it’s widely sold over the counter and is frequently used for treating seasonal allergies, motion sickness, and even insomnia.

Because it’s cheap, accessible, and doesn’t require a prescription, many American households—especially those with older adults—stock Benadryl without much thought. But that convenience may be hiding a major health concern.

How Benadryl Affects the Aging Brain?

Benadryl works by blocking histamine receptors, which helps reduce allergy symptoms. However, it also blocks acetylcholine, a neurotransmitter essential for memory and cognition. This action classifies it as an anticholinergic drug.

In young, healthy brains, this may cause only mild drowsiness. But in older adults, and especially those with already-declining acetylcholine levels (as is common in Alzheimer’s), Benadryl can cause:

Severe confusion

Memory problems

Hallucinations

Urinary retention

Dizziness and increased fall risk

These symptoms can easily be misinterpreted as progression of dementia—when in fact they may be drug-induced.

Alzheimer’s and Anticholinergic Drugs: A Dangerous Combination

In Alzheimer’s disease, acetylcholine levels in the brain are already significantly reduced. That’s why many Alzheimer’s medications, like Donepezil (Aricept), work by boosting acetylcholine activity.

When a drug like Benadryl suppresses that same system, it can worsen cognitive function, potentially accelerating the disease's progression.

A 2015 study from the University of Washington, published in JAMA Internal Medicine, found that chronic use of anticholinergic drugs was associated with a 54% increased risk of dementia. Benadryl was one of the drugs implicated.

Safer Alternatives for Allergies and Sleep in Seniors

If your loved one is suffering from allergies or insomnia, don’t reach for Benadryl first. Here are safer, evidence-based alternatives often recommended in the U.S.:

For allergies:

Loratadine (Claritin)

Fexofenadine (Allegra)

Cetirizine (Zyrtec) — use with caution in the very elderly
These are second-generation antihistamines and don’t significantly affect the brain.

For sleep:

Melatonin supplements (low dose, 0.5–3 mg)

Cognitive behavioral therapy for insomnia (CBT-I)

Addressing causes like pain, noise, or anxiety

Always consult a physician before switching medications, even OTC ones.