Benadryl is an antihistamine medication used to treat allergy and cold symptoms as well as sleep problems. Although it can be an effective treatment, Benadryl can cause side effects and risks, which can increase with long-term use. Benadryl can increase the risk of cognitive issues, such as dementia.
- Benadryl (diphenhydramine) is a first-generation antihistamine that helps with allergy symptoms and sleep issues.
- Benadryl causes side effects, including sedation and cognitive issues, and could increase the risk of dementia.
- Alternative treatments with fewer risks are available to help manage allergies and sleep issues.
The science: Does Benadryl cause dementia?
Various studies have investigated the impact of anticholinergic drugs like Benadryl on the development of dementia. Although these studies cannot explicitly state that the drugs themselves have caused dementia, their results suggest that the use of these medications is linked to an increased risk, specifically in older adults.
For example, one study (Gray et al, 2015) monitored over 3400 individuals aged 65 and over for ten years, tracking their use of anticholinergic drugs. During the study, 800 participants developed dementia, and it was found to be more likely in those who used anticholinergic drugs. [4]
Similarly, another study (Coupland et al, 2019) included a large group of people with dementia (58,769) and a control group (225,574), all 55 years or older. The use of anticholinergic medications in the decade prior was assessed. The results found a significantly increased risk of dementia in those with anticholinergic drug use and suggest that around 10% of dementia diagnoses can be linked to these medications.
These findings are significant, although further research is required to understand the association between anticholinergic medications and dementia risk, particularly the differences in risk associated with specific drugs.
Benadryl and the brain
Benadryl (diphenhydramine) is a first-generation antihistamine used to treat allergy and cold symptoms and insomnia. Benadryl crosses the blood-brain barrier, while second-generation antihistamines do not. This means that the side effects of the two generations of antihistamines differ considerably. [1]
First-generation antihistamines have an anticholinergic effect, as they interact with acetylcholine receptors, inhibiting acetylcholine activity. Anticholinergic drugs can be effective treatments for various conditions, including Parkinson’s disease, psychiatric conditions, respiratory disorders, and cardiovascular disease. [2][3]
However, anticholinergic effects can also be harmful and are likely to cause many adverse effects. These can include dizziness (a major risk factor for falls in older adults), sedation, headaches, anxiety, mood and behavior changes, insomnia, and impaired cognition and memory. [2]
Short-term vs. Long-term use
Short-term use of anticholinergic medications like Benadryl is likely to cause cognitive impairments, including impaired memory, attention, and speed. Generally, once the medication is stopped, these impairments are reversed. However, in some cases, cognitive impairments are irreversible, especially with long-term use. [4][5]
Research suggests that these medications can cause cumulative effects when used over several years, thereby increasing the risk of dementia with longer-term use. Gray et al showed a 54% higher risk in individuals using anticholinergic medications for three years or more when compared to the same dose used for three months or less. [4]
Side effects beyond dementia concerns
Aside from cognitive effects and the increased risk of dementia, Benadryl is likely to cause various side effects, particularly in high doses. Side effects can include: [1]
- Gastrointestinal issues
- Headache
- Dizziness
- Drowsiness
- Urinary retention
- Blurred vision
- Heart palpitations
- Change in heart rate
- Dry mouth
- Impaired coordination
- Reduced appetite
- Changes in mood and behavior
In high doses, Benadryl can cause overdose or toxicity, resulting in serious or life-threatening effects, including: [1][2]
- Seizures
- Arrhythmias
- Psychosis
- Severe confusion
- Delirium
- Hallucinations
- Uncontrollable shaking
- Rhabdomyolysis
Managing allergy and sleep issues safely, and other alternatives
Many alternatives are available for people who require treatment for allergy and sleep issues and are concerned about the side effects and risks of Benadryl.
Allergies
Second-generation antihistamines, such as loratadine and cetirizine, can safely manage allergy symptoms. Like Benadryl, they act on histamine receptors and effectively reduce symptoms such as runny nose, sneezing, and itching. However, unlike Benadryl and other first-generation antihistamines, they do not cross the blood-brain barrier and do not cause anticholinergic effects. This means that they are far less likely to cause side effects, sedation, and long-term risks. [5][6]
Other potential treatments for allergy symptoms include:
- Corticosteroid nasal sprays
- Decongestants
Sleep
Various treatments are available to help manage sleep issues, including medications, therapies, and lifestyle changes. Medications include: [7]
- Sedatives: Benzodiazepines, such as temazepam (Restoril) and triazolam (Halcion), and non-benzodiazepine hypnotics, such as zolpidem (Ambien) and zaleplon (Sonata). These medications can be safe for short-term use, but can be addictive and should not be used for more than a few weeks.
- Antidepressants: Some antidepressants, such as mirtazapine (Remeron), doxepin (Silenor), and trazodone, can be used for insomnia and sleep issues, often in low doses.
- Melatonin: Melatonin is a naturally produced hormone that helps regulate the sleep-wake cycle. It can be taken orally to help improve sleep issues.
Medications can be helpful in the short-term treatment of sleep issues, but can be habit-forming and do not manage the underlying cause of sleep disturbances. As such, it can be helpful to utilize non-medicinal strategies, such as: [7]
- Therapy: Talk therapy can help identify and manage underlying causes of sleep disturbances, such as stress and anxiety. This not only prevents risks associated with medications but also helps to formulate long-term strategies to manage sleep issues.
- Relaxation and mindfulness techniques: Similarly, relaxation and mindfulness can help people manage psychological issues contributing to sleep problems.
- Sleep hygiene: Making changes to daily habits and bedtime routines can help improve sleep. For example, avoiding caffeine and alcohol late in the day, avoiding screens before bed, ensuring the bedroom is dark and quiet, and going to bed and waking up at the same time each day.
What to do if you're concerned about dementia
People who are concerned about developing dementia may wish to avoid anticholinergic medications such as Benadryl, particularly for long-term use.
If someone notices signs that may be indicative of dementia, they should consult their doctor. The doctor can assess their mental state and cognitive functioning to help determine the presence of dementia. They might conduct tests, such as blood tests or brain scans, to help understand the cause of these symptoms, as other conditions may be associated with cognitive impairments.
Dementia cannot be cured, but symptoms can be managed with certain treatments that help slow the progression of the condition. As such, early diagnosis can be crucial. Additionally, early diagnosis can enable individuals and their families to plan for future treatment needs.
Should you stop taking Benadryl?
As there are alternatives available that pose less risk, it is advisable to use other treatments instead of Benadryl, particularly if long-term treatment is required. People who require a new treatment can discuss the available options with their prescribing physician and decide on a medication with fewer risks.
People currently using Benadryl can change to an alternative treatment, although they should not stop taking the medication without professional guidance.
Final thought
The side effects of Benadryl, particularly anticholinergic effects, can be especially risky for older adults, potentially increasing the risk of falls and confusion, and the development of dementia. As such, it is not a recommended treatment for this age group. [6]
Even in short-term use, Benadryl can cause undesirable effects, including sedation and impaired cognitive performance, even the day after administration. Thus, it can impact professional and academic functioning. [5]
Scientific literature has developed in recent years, and it is generally acknowledged that Benadryl and other first-generation antihistamines pose more potential risk than benefit, particularly as alternative treatments with fewer risks are available. [5][6]
