The Long-Term Effects of Benadryl

Last updated: September 2022

Have you, like me, been taking Benadryl, to both calm down the burning itch of eczema as well as allow you to sleep when the world and your skin just become too much to allow some decent rest? Did you know it may not be the best idea over time?

Anticholinergics and dementia?

I’ve been using Benadryl or its generic equivalent for my itchy eczema for as long as I can remember. As well as for my seasonal allergies. Now as a senior, I occasionally use it to help me fall asleep as well. But recently, I’ve been seeing mention of a link between long-term use of anticholinergic medications like diphenhydramine (the active ingredient in Benadryl) and dementia. As a senior, dementia is always a worry, especially when I can’t quickly recall the exact word I want. For those taking tricyclic antidepressants, remember they are anticholinergics as well.

What are anticholinergics?

To understand these studies, I needed a science lesson. Here’s a brief recap of what I’ve discovered about anticholinergics.

Anticholinergic drugs block the action of acetylcholine, a substance that acts as a chemical messenger. It transmits signals between cells. In the brain, acetylcholine is involved in learning and memory. In the rest of the body, it stimulates muscle contractions. Anticholinergics include first-generation antihistamines such as Benadryl, tricyclic antidepressants, and medication for Parkinson’s disease. They are used to treat various conditions.

Wyhy am I concerned about antihistamines?

Science lesson over. Now on to the reasons I’ve become concerned about which antihistamines to take.

I first came across this: In 27 studies, all but 2 found an association between the anticholinergic activity of medications and either delirium, cognitive impairment, or dementia!1

What about Benadryl?

Benadryl seems like a very innocuous little over-the-counter pill, one we’ve trusted for well over half a century. But more research led me to this: "In...persons aged 65 years and older, we found that higher cumulative use of anticholinergic medications is associated with an increased risk for of all-cause dementia and Alzheimer’s disease."2

Since Benadryl is available over-the-counter, your doctor needs to be made aware if you are taking it, as it might not be wise to take something like a tricyclic antidepressant as well.

Benadryl is approved for short-term or temporary usage, not intended for long-term use. You may develop a tolerance to it when using it to help with sleeplessness. After 4 nights, it was found to be no more effective as a sleep aid than a placebo, but the antihistamine effect doesn’t seem to be affected.3

So what am I doing now?

This has led me to re-evaluate all the drugs, including over-the-counter, prescription, and even natural products such as herbal teas. Looking at each to see if they’re actually still doing what I expect, and not doing anything negative. But also to double-check if there are any interactions.

When you’re having an acute allergic reaction, it can be a lifesaver. But as with most medications, we should use the smallest dosage that provides the desired effect.

I’ll still use Benadryl when necessary, but with more thought about that necessity. As a side note, it was first made available for commercial use the year I was born.

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