This Common Over-The-Counter Medication Increases Dementia Risk, According To Doctors

Over the last couple of years, stress started interrupting my sleep. I found myself having difficulty falling asleep and, even when I did, waking up in the middle of the night. As a freelancer who makes my own schedule, I attempted to fill in the gaps with occasional naps, but it was still a vicious cycle of feeling constantly exhausted during the day, only to not be able to doze off when my head hit the pillow.

Still, I didn’t think my issues were serious enough to warrant a doctor’s visit (and didn’t want to deal with the hassle of potentially having to find and see a specialist), so I turned to what I thought was the next best option: Unisom, an over-the-counter sleep aid. There’s just one problem about taking this sleep shortcut: meds like Unisom, a.k.a. doxylamine succinate—which are found in both OTC sleep aids and allergy meds—are actually pretty bad for your brain health.

Though most sleep aids and certain allergy med labels indicate that they’re not intended for long-term use, they often don’t say why. A close friend who is also a physician clued me into why these OTC options aren’t ideal: Frequent use of antihistamines that fall into the category of first-generation antihistamines has been tied to an increased risk of dementia. In fact, a study published this year in the World Allergy Organization Journal suggests people should avoid taking Benadryl, which is a first-gen antihistamine, altogether. (And, BTW, these meds were put on the market all the way back in 1946, before they were required to undergo safety testing, according to research by the the Journal of Allergy and Clinical Immunology.)

This is a serious concern among medical experts, says Pamela Tambini, MD, an internal medicine physician and medical director at Engage Wellness. “People sometimes assume these medications must be harmless because they are sold over the counter, but if you use them too often or for too long, they can mess with your thinking, make you groggy during the day, and possibly lead to long-term problems,” she says.

So while they might be safe to take every once in a while, here’s why doctors strongly recommend considering other options for sleep or allergies.

Meet the experts: Pamela Tambini, MD, a Palm Beach Gardens, FL-based double board-certified physician in internal and addiction medicine and medical director at Engage Wellness in Acton, MA, Seetha Bhagavatula, MD, a Maryland-based board-certified geriatrician and internal medicine physician at Remo Health.

Here’s why first generation antihistamines are bad for your brain health.

First, a quick refresher on what antihistamines are exactly. Antihistamines are medications that work primarily to block histamine, a chemical released by the immune system during allergic reactions or infections, says Seetha Bhagavatula, MD, a board-certified geriatrician and internal medicine physician at Remo Health. Histamine is what causes the uncomfortable allergy symptoms you might experience like a runny nose, itchy eyes, or irritated skin. Luckily, “by preventing histamine from binding to its receptors, antihistamines effectively reduce these allergy-related symptoms throughout the body,” says Dr. Bhagavatula.

They’re an easily available solve for people with mild seasonal allergies, but these meds affect more than just your runny nose. They also make you sleepy (which is why they pop up in OTC sleep medications) and affect many other systems in your body, Dr. Tambini says. “Since histamine also helps keep you awake, blocking it makes you feel sleepy, which is why they’re often used in sleep aids—they sort of sedate you as a side effect,” Dr. Tambini says.

However, patients with allergic rhinitis (commonly known as “hay fever”) taking first-generation antihistamines face an increased risk of developing dementia, according to a 2src24 study in the Journal of Allergy and Clinical Immunology. The study also found some risk with second-generation antihistamines, but the risk was far lower. “There might still be a slight risk for cognitive effects,” says dr. Tambini. “However, that risk is very low for most healthy adults taking them occasionally or even seasonally.”

That’s because there’s another major system certain antihistamines affect: Your brain. Older antihistamines, known as first-generation antihistamines, such as diphenhydramine (ZzzQuil) and doxylamine (Unisom) cross into the brain and block histamine receptors there, whereas second-generation antihistamines were designed to avoid that, says Dr. Tambini. They specifically target acetylcholine—which happens to be a key brain chemical involved in memory, focus, and learning. This makes an impact on long-term brain health, according to the research. Frequent sleep medication use was associated with an increased risk of dementia in older adults, highlighting that risk may vary by race as well, according to a 2src23 study in the Journal of Alzheimer’s Disease.

“If you are constantly dampening that system with these medications, your brain does not function as well,” Dr. Tambini says. “Over time, that can lead to memory issues or even contribute to cognitive decline, particularly if you’re already at risk.”

In older adults, these medications can also cause confusion or even increase the risk of falling, but the biggest concern is how they impact the brain over time, especially when used frequently, Dr. Tambini says.

Medications that contain first-generation antihistamines:

• For sleep: Unisom (doxylamine succinate), Sominex (diphenhydramine HCl), Tylenol Simply Sleep (diphenhydramine HCl), ZzzQuil (diphenhydramine HCl)

• For allergies: Benadryl (diphenhydramine), Chlor-Trimeton (chlorpheniramine), Dramamine (dimenhydrinate), Vicks NyQuil (doxylamine succinate)

They’re also not even that helpful for your sleep, either.

If you’ve ever taken these meds to help you sleep, you may find you knock out and sleep hard on the first night that you’re particularly exhausted. But as you continue them, you might also feel groggy or foggy the next morning, even if you slept a full eight hours, making their intended use backfire.

These meds actually worsen your sleep quality in the long run, even if they still help you fall asleep fast, Dr. Tambini says. “These meds can reduce REM sleep—the deep, dream-filled sleep that really restores your brain,” she explains. “So you might technically be asleep for hours but still wake up feeling sluggish or unrefreshed because it’s like getting the quantity of sleep without the quality.”

What To Take Instead Of First-Generation Antihistamines

What’s more important than finding the perfect sleep aid is nailing why exactly you’re looking to find one, especially if you may have other underlying health factors that could increase negative side effects, says Dr. Bhagavatula. Whether it’s stress, poor sleep hygiene, side effects of another medication, or insomnia, you’re going to want to get to the bottom of your sleep issues to find the best treatment.

“Sleep is complex, and while reaching for a quick fix might be tempting, those fixes sometimes cause more problems than they solve,” Dr. Tambini says. “There are safer, more effective options out there—and talking to your doctor is a great first step in figuring out what’s really going on and how to get your sleep back on track.”

But, it is okay to occasionally use an OTC sleep aid such as Unisom or ZzzQuil in a pinch, she says. “Taking something for a night or two can be fine if you’re dealing with a temporary sleep issue—like jet lag or stress before a big event,” Dr. Tambini says. “[But once you] build up a tolerance, which can happen in just one to two weeks of regular use, they stop working as well, and your body starts relying on them, you’re not actually addressing the root cause of why you can’t sleep in the first place.”

Long-term, both Dr. Tambini and Dr. Bhagavatula advise looking into solutions that *don’t* affect your brain health, which include:

For Sleep

Alternatives to something like ZzzQuil include supplements like melatonin and valerian root, which some people find helpful, according to Dr. Tambini (but the science isn’t completely settled on yet, per a 2src2src systematic review and meta-analysis in the Journal of Evidence-Based Integrative Medicine).

If you’re really struggling to catch some Zzzs, though, both docs recommend cognitive behavioral therapy for insomnia, which is the most effective treatment, per a 2src22 study in Clinical Psychology and Special Education. It helps you build better sleep habits and teaches your brain how to sleep again, says Dr. Tambini. This is something that takes multiple sessions to work, so it’s not quite an in-the-moment fix like popping a melatonin.

And, there are a few prescriptions that doctors have at their disposal, too. Personally, I swapped Unisom for trazodone, an antidepressant commonly prescribed off-label to treat insomnia, which I’ve found to be helpful so far.

Talk to your primary care physician when considering any sleep medications, including OTC options, especially if taking other medications that could potentially interact with a sleep aid and increase the risk of certain side effects, says Dr. Bhagavatula.

For Allergies

If you’ve been taking these medications for allergies rather than sleep problems, you don’t need to opt to suffer in favor of promoting good brain health.

“Newer, second-generation antihistamines like Claritin, Zyrtec, and Allegra don’t cross into the brain as much, so they don’t cause that drowsy, brain-fog feeling,” says Dr. Tambini. “If allergies are your issue, those are much better choices—especially for daily use.”

Steroid nasal sprays, for example, aren’t antihistamines at all—and they’re actually the best option for moderate to severe seasonal allergy sufferers, allergy specialists previously told Women’s Health.

Basically, it’s time to put down the Benadryl and go with something a little newer.

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