Q: My allergist says that Benadryl isn’t safe. What’s the issue, and what should I use instead?
When your nose is running and the achoos won’t quit, you might reach for Benadryl.
This drug — whose generic name is diphenhydramine — provides almost immediate allergy relief. And with Benadryl around since the 1940s, it’s become the “Kleenex” of antihistamines, said Dr. Anna Wolfson, an allergist at Massachusetts General Hospital.
But experts believe it’s time to say goodbye because of how older antihistamines like Benadryl cross the blood-brain barrier, causing grogginess and increasing the risk of falls, car accidents and potentially even dementia.
If you’re on a deserted island and Benadryl is the only allergy drug available, you should take it, Dr. Wolfson said. But in almost every other case, there are safer, better options.
How does Benadryl work?
Our bodies produce the chemical histamine to rally the immune system against germs. But the same alarm can be set off by springtime flowers, peanuts and other menaces. Antihistamines block this false alarm, helping prevent or relieve allergy symptoms.
Benadryl, Zzzquil and other drugs with diphenhydramine can also make you drowsy, since histamine helps the brain stay alert, said Dr. Zachary Rubin, an Illinois-based allergist and author of the upcoming book, “All About Allergies.”
But this comes at the cost of your rapid eye movement (REM) sleep, which is important for memory consolidation and overall brain function. The feeling is more like being knocked out after having too much to drink, than deep, restorative sleep, Dr. Rubin said.
“You have this lingering hangover effect,” said Dr. David Stukus, director of the Food Allergy Treatment Center at Nationwide Children’s Hospital, with people having difficulties paying attention, remembering things clearly or even staying awake.
Benadryl has been associated with worse school performance and, in one small study, impaired people’s ability to drive more than alcohol. The European Union has put the drug on its “do not drive” list, and pilots are not allowed to fly if they’ve taken Benadryl in the past two to three days.
Is Benadryl linked with dementia?
In addition to blocking the histamine signal, Benadryl interferes with the brain chemical acetylcholine, which is responsible for attention, concentration and memory, said Dr. Malaz Boustani, a geriatrician and neuroscientist at Indiana University. And an increasing body of research is linking regular use of these drugs to a higher risk of dementia.
In a 2015 study in JAMA Internal Medicine, researchers followed over 3,000 older adults without dementia for seven years and found that frequent long-term use of acetylcholine-blocking drugs was associated with 54 percent higher risk of dementia and 63 percent higher risk of Alzheimer’s disease. Experts say these results don’t prove that Benadryl specifically causes dementia, and it’s not clear whether the risk extends to younger people or even short-term use.
But given the growing body of evidence tying older antihistamines to cognitive decline, Dr. Boustani said he doesn’t prescribe Benadryl.
Diphenhydramine is also found in over 300 different products, including some NyQuil and Tylenol products, so Dr. Boustani recommends that patients read the labels of their favorite allergy, sleep or cold medications — and ask a pharmacist if they’re not sure.
Are there safer, better options?
Occasional use is fine, Dr. Wolfson said, and nobody needs to run home and throw out their stash. But next time you’re at the pharmacy, she recommended buying newer antihistamines, such as cetirizine and fexofenadine — commonly known as Zyrtec and Allegra.
Since these drugs are less able to cross into the brain, they are linked to fewer issues than Benadryl, said Dr. Sarah Taylor-Black, an allergist at Dartmouth Health. While Zyrtec offers fast-acting relief and Allegra has fewer side effects, both are more long-lasting than Benadryl.
For sleep, doctors recommend starting with healthy bedtime rituals, like avoiding your phone before bed and sticking to a consistent nighttime routine. You can also consider taking melatonin and magnesium supplements. Although they won’t knock you out as quickly, experts say they’re safer than Benadryl.
But if you find that you’re using any antihistamine more than two to three times per week, it’s worth talking to your doctor, said Dr. Rita Kachru, chief of clinical allergy and immunology at UCLA Health. It might be masking an underlying sleep disorder, which is best treated with insomnia medication or cognitive behavioral therapy. For allergies, you might be able to cut back on antihistamines by avoiding triggers and using saline to clear your sinuses, she said. If that doesn’t work, your doctor might prescribe a steroid nasal spray, which is more effective than antihistamines, or give you allergy shots to reduce your reaction severity.
Ultimately, experts say there is little reason to take Benadryl for more than a couple days. “You can choose to drive a 1976 Impala, or you can choose to drive a more modern automobile,” Dr. Stukus said. “Just because you’ve always done something a certain way, it doesn’t mean it’s the best option available.”
Simar Bajaj covers health and wellness.
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