Key takeaways:
Diphenhydramine (Benadryl) belongs to two classes of medications: antihistamines and anticholinergics.
Some research studies suggest that frequent use of anticholinergic medications may increase the chances of developing dementia. But no study has looked specifically at Benadryl.
Benadryl still has some other side effects that can be harmful for older adults. If you take Benadryl often, talk to your care team about safer medications to help with your symptoms.
Media reports have raised interest in whether Benadryl causes dementia. It’s an important question, but the answer isn’t so clear. Should you be concerned about this common medication? Let’s find out.
What is Benadryl?
Diphenhydramine (Benadryl) is an over-the-counter (OTC) antihistamine medication.
People use this oral medication to help with:
Seasonal allergies (hay fever)
Common cold symptoms
Hives or itchy skin
Like other first-generation (older) antihistamines, Benadryl can make you very sleepy. For that reason, it’s also used as a sleep aid.
How does Benadryl work?
Benadryl is both an antihistamine and an anticholinergic medication. This means it works in two ways:
It blocks the action of histamine. This is a natural chemical in the body that’s released during an immune response. Histamine causes symptoms like itching, sneezing, congestion, and runny nose. So, blocking histamine helps relieve those symptoms.
It blocks the effect of acetylcholine. This is a chemical in the brain that helps send messages between cells. Blocking acetylcholine can cause temporary drowsiness, confusion, and memory loss. As we’ll cover below, this is a key component of the link between Benadryl and dementia.
What is dementia?
Dementia is a group of conditions that affects brain function, like memory, judgment, problem-solving, and orientation. Dementia impacts someone’s day-to-day life and makes it harder for them to care for themselves. The most common type of dementia is Alzheimer’s disease.
Dementia can make it more difficult to do things, like:
Remembering people, events, or places
Finding your way home
Concentrating on tasks
Communicating with others
Solving problems
Planning actions
Accomplishing daily tasks
Organizing things
Some people with dementia also experience:
Confusion
Anxiety
Depression
Personality changes
Agitation
Does Benadryl cause dementia?
It’s unclear whether Benadryl causes dementia. We’ll get into the research studies below. But it’s important to know that experts encourage older adults to avoid Benadryl when possible. This is due to side effects as well as the risk of dementia. They recommend taking other medications first, depending on symptoms.
What does the research say about Benadryl and dementia?
Several studies have found a link between anticholinergic medications and dementia. But determining what causes this link is hard. Although the research hasn’t found a definitive link between Benadryl specifically and dementia, the findings raise a cautionary flag.
Let’s take a closer look at the current research:
A long-term follow-up study involved people who took an anticholinergic medication every day for more than 3 years. The study found that they had a significantly higher risk of developing dementia compared to people who didn’t take these medications at all. But the study didn’t report on individual medications, like Benadryl.
A short-term follow-up study found that people taking anticholinergic medications had signs of brain shrinkage on MRI scans. They also scored lower on mental tests compared to people who weren’t taking the medications. These findings point toward dementia, but it doesn’t necessarily mean that the affected people had dementia. The study also didn’t determine which specific medications (such as Benadryl) were linked to the MRI results and test scores.
A more recent Cochrane review of 25 studies found “low-quality” evidence of an increased risk of dementia in people who didn’t already have cognitive impairment. But again, this involved people taking any anticholinergics, not just antihistamines.
Other research studies that looked specifically at antihistamines. These didn’t find an association with dementia:
A 2019 study found a link between dementia and several classes of anticholinergic medications used to treat depression, schizophrenia, bipolar disorder, seizures, Parkinson’s disease, and overactive bladder. But there was no association between dementia and antihistamine medications.
A 2018 study had similar findings. Though certain types of anticholinergic medications were linked to dementia, antihistamines weren’t.
These studies have important limitations to be aware of:
You can buy many antihistamines, including Benadryl, without a prescription. That means it’s difficult for researchers to know exactly who was and wasn’t taking the medications during the studies.
The studies were observational. This means that other factors may explain the links between dementia and medications.
Other factors that weren’t measured in the studies may have raised the risk for dementia. These factors include genes, certain medical conditions, and environmental exposures.
Should you stop taking Benadryl?
The research to date hasn’t proven that Benadryl raises the risk of developing dementia. But Benadryl’s medication class (anticholinergics) does appear to be associated with dementia.
If you take Benadryl, talk to your primary care provider. They can help you decide if you should stop taking Bendryl, other antihistamines, or other anticholinergics. You may agree that you should keep taking Benadryl. If so, you can follow these tips to lower your potential risk of dementia or other complications:
Dose: Take the lowest effective dose for the shortest time.
Side effects: Pay attention to the side effects of Benadryl, especially if you’re an older adult. The body responds differently to Benadryl as you get older. And you may develop side effects that were never a problem before.
Length of use: Benadryl isn’t intended to be used as a daily, long-term medication for sleep or other issues. If you’re taking Benadryl on a regular basis to help with your symptoms, see a healthcare professional.
If you’re concerned about your risk for dementia, there are other steps you can take. These include getting regular exercise, good sleep, social activity, and proper nutrition.
Frequently asked questions
Short-term side effects of Benadryl — like drowsiness, dry mouth, and confusion — should resolve after you stop taking it. That said, the cumulative (build up) effects of long-term Benadryl use on memory and cognition aren’t quite clear.
Any kind of change can be a big trigger for behavioral change in people with dementia. This could be a change in environment, routine, or caretakers. Other things that can increase the risk include medications, infection, or overstimulation.
It’s not a good idea to take any OTC sleep aid every night, including Benadryl. You can build tolerance to it or become dependent on it. If you struggle with sleep every night, it’s a good idea to get help from a healthcare professional. They can help you sort through possible causes and what to do next.
Short-term side effects of Benadryl — like drowsiness, dry mouth, and confusion — should resolve after you stop taking it. That said, the cumulative (build up) effects of long-term Benadryl use on memory and cognition aren’t quite clear.
Any kind of change can be a big trigger for behavioral change in people with dementia. This could be a change in environment, routine, or caretakers. Other things that can increase the risk include medications, infection, or overstimulation.
It’s not a good idea to take any OTC sleep aid every night, including Benadryl. You can build tolerance to it or become dependent on it. If you struggle with sleep every night, it’s a good idea to get help from a healthcare professional. They can help you sort through possible causes and what to do next.
The bottom line
Benadryl is both an antihistamine and an anticholinergic medication. Some research suggests that anticholinergic medications can increase the risk for dementia. But the link isn’t totally clear. No studies have found that Benadryl specifically causes dementia.
Still, experts don’t recommend regular use of Benadryl. This is especially true for older adults, who may experience more side effects. If you take it a lot, talk to your healthcare team. They can suggest other options to avoid unwanted side effects and decrease any chance (even a small one) of developing dementia.
Why trust our experts?
References
2023 American Geriatrics Society Beers Criteria Update Expert Panel. (2023). American Geriatrics Society 2023 updated AGS Beers Criteria for potentially inappropriate medication use in older adults. Journal of the American Geriatrics Society.
Alzheimer’s Association. (n.d.). Treatments for behavior.
American Family Physician. (n.d.). Don’t recommend highly anticholinergic medications in older adults without first considering safer alternatives or non-drug measures.
Coupland, C. A. C., et al. (2019). Anticholinergic drug exposure and the risk of dementia – A nested case-control study. JAMA Internal Medicine.
Gray, S. L., et al. (2015). Cumulative use of strong anticholinergics and incident dementia – A prospective cohort study. JAMA Internal Medicine.
Nemours KidsHealth. (n.d.). Definition: Histamine.
Richardson, K., et al. (2018). Anticholinergic drugs and risk of dementia: Case-control study. The BMJ.
Risacher, S. L., et al. (2016). Association between anticholinergic medication use and cognition, brain metabolism, and brain atrophy in cognitively normal older adults. JAMA Neurology.
Taylor-Rowan M., et al. (2021). Anticholinergic burden (prognostic factor) for prediction of dementia or cognitive decline in older adults with no known cognitive syndrome. Cochrane Database of Systematic Reviews.
