The problem with Benadryl and what to take now

It’s probably in your medicine cabinet — a favorite go-to, over-the-counter remedy for colds, hives and even poison ivy.

You might also pop a Benadryl without a second thought if you’re having trouble dozing off the night before a big meeting or want to head off motion sickness before a road trip.

Think twice, urges Jessica Harpell, a certified physician assistant specializing in family medicine at Novant Health Hilton Head Primary Care in South Carolina. A remedy once recommended by doctors has fallen out of favor because newer antihistamines pose fewer risks.

Safer alternatives are available, she said, noting that diphenhydramine, the first-generation antihistamine in Benadryl and many other over-the-counter meds, poses particular safety risks to older people and young children. Research has even pointed to a link between its frequent use in seniors and dementia.

That’s why Harpell is among a growing number of doctors, nurse practitioners, physician assistants (PAs) and pharmacists recommending next-generation alternatives, which work without significant effects on the brain.

Harpell shared what patients need to know:

What are antihistamines?

These drugs prevent an unwanted release of chemicals, called histamines, from the body. While histamines help your body fight disease-causing germs, allergens like cat hair, pollen and peanuts may also trigger these chemicals, causing symptoms such as a rash, sneezing, runny nose or tightness in airways. As the name implies, antihistamines counter these unwelcome effects.

Why does Benadryl make you sleepy?

Like other first-generation antihistamines, Benadryl works by targeting histamine-1 receptors in your blood vessels, gut and airways. The sedative effect owes to its ability to cross into the brain, which also has these receptors. That, Harpell explained, is why you should never drive or operate machinery when using it.

In contrast, newer, second-generation antihistamines like cetirizine (Zyrtec), loratadine (Claritin) and fexofenadine (Allegra) don’t cross the blood-brain barrier as readily so they have fewer side effects. These new antihistamines are also less likely to interact with other meds, Harpell said.

Is diphenhydramine found in other over-the-counter remedies?

You’ll find it on the labels of more than 300 products, including meds to ease congestion, pain relievers and fever reducers. Those include over-the-counter remedies like Tylenol PM, Sudafed PE Day & Night Cold, Midol PM, ZzzQuil and Theraflu Nighttime Severe Cold & Cough. Harpell said this is why it’s so important to read product labels or seek the advice of a pharmacist or healthcare provider.

Does Benadryl cause dementia?

The evidence isn’t conclusive, Harpell said, but research published in JAMA Internal Medicine sounded a warning 10 years ago. The study followed more than 3,400 seniors for about seven years. Over that time, 797 developed dementia and 637, possible or probable Alzheimer’s disease.

Participants who often used common anticholinergic drugs, including antihistamines like Benadryl, had a 54% higher risk for dementia and 63% higher risk for Alzheimer’s disease, the study found.

While Harpell emphasized that doesn’t prove anticholinergics cause these conditions, it does suggest a link.

Benadryl interferes with a brain chemical called acetylcholine, which is essential to memory, concentration and attention. A drop in acetylcholine levels is a hallmark of Alzheimer's.

The American Geriatric Society has a list called the Beers Criteria, which spells out whether medications are safe or not for people over 65, and Benadryl is on that list, which means proceed with caution.

What other risks does Benadryl pose for older people?

For seniors, its sedative effect increases the risk for a fall — a leading cause of injury from which some never recover.

Because of the potential for interactions with prescription meds, she suggests seniors chat with a pharmacist or their primary care provider before taking over-the-counter medications.

Is Benadryl safe for kids?

Benadryl’s sedative effect also poses risks to kids under 6, Harpell said, and parents should never give it to a child to help them get to sleep. This use of antihistamines has been linked to next-day drowsiness, as well as poor attention and school performance.

Kids also may react to Benadryl in unexpected ways — owing to differences in their histamine-1 receptors.

Think of these receptors like buckets that can fill with the medication. If you put too much medication in their system, it’s going to start hitting other receptors, too, and that’s going to have the reverse effect and make them hyper.

Children’s formulations of next-generation meds like Zyrtec, Claritin and Allegra are a safer choice, she said. The National Library of Medicine has one more caution: Never give children diphenhydramine products that are made for adults.

What’s the alternative?

Harpell advises patients to limit their use of any over-the-counter med to two weeks, tops. If you need it after that, talk to your doctor. A prescription med may be a better option, she said.

When it comes to antihistamines, Harpell recommends choosing a second-generation drug like Allegra, Claritin, Xyzal or Zyrtec – or the generic equivalents – which are fast-acting and have fewer side effects.

Anything else?

Anyone who is having signs of a potentially fatal allergic reaction called anaphylaxis — swelling of the lips, tongue or throat, hives, difficulty breathing and dizziness — needs immediate medical care, Harpell emphasized. That includes epinephrine and a trip to the E.R.