I recently gave a presentation about reducing the risk of dementia and received a question from Linda about Benadryl, the active ingredient in many over-the-counter sleep aids. Linda’s question was this:

I heard that Benadryl causes dementia. Is that true?

What the Research Says

There is some research suggesting a potential link between the long-term use of anticholinergic medications, including Benadryl (diphenhydramine), and an increased risk of dementia in older adults. Anticholinergic drugs block the action of acetylcholine, a neurotransmitter in the brain, and this blockade has been associated with cognitive impairment.

A study published in JAMA Internal Medicine in 2015 found an association between the use of anticholinergic medications and an increased risk of dementia. However, it's essential to note that this association does not establish a direct causal relationship. The study observed an association, but causation remains uncertain. Additionally, individual responses to medications can vary, and other factors may contribute to the development of dementia.

A 2018 study analyzed the link between antihistamines (which also contain Benadryl) and did not find an association with dementia. There was an increased risk of dementia in patients taking antidepressant, urological, and anti-Parkinson drugs.

These are just two studies. We need more research into the link between anticholinergic drugs and neurological disease.

Other Side Effects of Benadryl

I’m not a fan of over-the-counter sleep aids with Benadryl because one proven side effect is dizziness. This greatly increases the risk of falls, especially if you get up in the middle of the night and are feeling light-headed. My top advice is to avoid these over-the-counter medicines if at all possible.

However, I’m not a medical professional so I always advise individuals to consult with their healthcare providers about supplements.