It’s not at all uncommon to have some Benadryl stashed in your medicine cabinet. The over-the-counter (OTC) antihistamine uses an active ingredient known as diphenhydramine to help the body counteract itchiness or seasonal allergies and to quell some low-grade allergic reactions. While it’s certainly helpful for finding relief in a pinch, experts say there could be some adverse long-term effects associated with its use—including an increase in dementia risk.
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Research suggests a link between OTC drugs like Benadryl and cognitive decline.
While you might be most familiar with the name Benadryl, it’s actually just one type of medicine in a larger group known as anticholinergic drugs. These medications specifically work by blocking acetylcholine, which is a neurotransmitter, according to Cleveland Clinic.
Because of their ability to regulate the nervous system, some drugs in this family are used for treating serious conditions, including Parkinson’s disease, overactive bladder, and asthma. However, because Benadryl and other OTC medicines that contain diphenhydramine cause drowsiness, some also reach for the drug when they’re having trouble falling asleep.
Unfortunately, those who rely on products like Benadryl too often could be increasing their long-term cognitive health risks. In a study published in the journal JAMA Internal Medicine, a team of researchers used data provided by 3,500 participants aged 65 and older. All were part of a long-term joint study known as Adult Changes in Thought (ACT), which granted the team access to participants’ prescriptions and the medicines they purchased for a decade before the study began.
The researchers then observed participants for about seven years, during which time roughly 800 of them were diagnosed with dementia, per Harvard Health Press. Ultimately, results found that those who had used anticholinergic medications like Benadryl were more likely to experience cognitive decline. This was especially true of participants who took the drugs regularly, with the team finding those taking one of the drugs for three years or more were 54 percent more likely to develop dementia than participants who only took them for three months or less.
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Anticholinergic drugs can be especially risky for seniors.
In addition to the long-term considerations for brain health, there are significant short-term considerations that could specifically pose problems for older individuals. According to Harvard Health Press, the body begins producing less acetylcholine the older we get, meaning a normal dose might hit harder than a healthy younger person.
Other changes to the body can also play a part. Since vital organs might work more slowly in seniors, drug levels can sometimes stay higher for longer periods of time. And since older people are more likely to take more prescription drugs, there’s also an increased risk of interactivity between their daily regimen and OTC medicines, per Harvard.
How can you avoid taking too much Benadryl?
For many patients, overuse or misuse of anticholinergic medications tends to stem from other issues. According to Philip Alapat, MD assistant professor at Baylor School of Medicine, this is why it’s important to consult your doctor if you’re still struggling—especially difficulty falling asleep, he wrote for the school's website.
"For many people, insomnia is short-term due to a stressful event or family problems. In this context, for a brief period, it’s not unreasonable to consider pharmacological agents to help you get to sleep, but even in this situation, people should consult a physician to determine what medication might work best," he said.
The takeaway:
Research has shown that anticholinergic medicines like Benadryl could pose an increased risk of dementia. A study found that out of 3,500 patients, those who regularly took the medicines were more likely to develop the condition.
Instead of using the antihistamine for off-label purposes, doctors suggest seeking medical attention to address issues like insomnia.
