For decades, diphenhydramine, the active ingredient in Benadryl, has been a common over-the-counter remedy for allergies and sleeplessness. However, a growing body of evidence and official guidelines from organizations like the American Geriatrics Society (AGS) confirm that this medication is unsafe for individuals aged 65 and older. The risks associated with Benadryl's pharmacology and the physiological changes that come with aging far outweigh its potential benefits for this demographic.
The Problem with Anticholinergic Effects
Benadryl is classified as a first-generation antihistamine, which means it can easily cross the blood-brain barrier. Once in the brain, it blocks acetylcholine, a crucial neurotransmitter responsible for attention, memory, and concentration. This action is what makes the drug effective at causing drowsiness, but it also leads to a range of undesirable and dangerous side effects, especially in seniors. As people age, their brain's production of acetylcholine already naturally declines, so blocking its effects with a medication like Benadryl can have a much more pronounced and harmful impact.
Why Older Bodies React Differently
As the body ages, several physiological changes occur that alter how medications are processed, making Benadryl's effects more potent and longer-lasting in seniors.
Slower Drug Clearance
- Reduced Kidney and Liver Function: With age, the kidneys and liver, which are responsible for clearing drugs from the bloodstream, become less efficient. This means diphenhydramine stays in the body longer, increasing its concentration and the duration of its side effects.
- Altered Body Composition: A shift towards more body fat and less muscle mass changes how drugs are distributed and metabolized, further affecting drug levels.
Significant Risks for People Over 65
The anticholinergic effects of Benadryl, combined with the body's age-related changes, create a high-risk scenario for older adults. These risks are why the AGS Beers Criteria lists first-generation antihistamines as potentially inappropriate for seniors.
Increased Risk of Falls
Sedation, dizziness, and impaired balance are common side effects of Benadryl that can significantly increase the risk of falls in older adults. A fall can lead to severe injuries, including bone fractures, and diminish a senior's independence. This risk is compounded by the fact that older individuals may have other medical conditions or take other medications that also contribute to balance issues.
Cognitive Impairment and Dementia
Several studies have shown a concerning association between long-term or frequent use of anticholinergic medications and cognitive issues. A study in JAMA Internal Medicine found that older adults who used anticholinergic drugs daily for three years or more had a significantly higher risk of developing dementia. While this research shows an association rather than causation, the evidence is strong enough that medical professionals advise caution. Acute side effects can also include severe confusion, memory problems, and a state similar to delirium.
Other Adverse Effects
Beyond cognitive issues and falls, Benadryl can cause other troublesome and sometimes dangerous side effects in seniors:
- Dry mouth and eyes
- Constipation
- Urinary retention, which can increase the risk of urinary tract infections (UTIs)
- Blurred vision
- Heart-related issues, such as a fast or irregular heartbeat
Safer Alternatives to Benadryl
Fortunately, there are safer and more effective alternatives for both allergy symptoms and sleep issues. Healthcare providers recommend focusing on second-generation antihistamines and non-pharmacological methods for insomnia.
Comparison of Benadryl (First-Gen) vs. Second-Gen Antihistamines
| Feature | Benadryl (Diphenhydramine) | Second-Generation Antihistamines (e.g., Zyrtec, Allegra, Claritin) |
|---|---|---|
| Classification | First-Generation | Second-Generation |
| Effect on Brain | Easily crosses blood-brain barrier. | Does not easily cross blood-brain barrier. |
| Sedation | Very high risk; commonly used as a sleep aid. | Non-drowsy; minimal sedative properties. |
| Anticholinergic Effects | High, causing confusion, dry mouth, etc.. | Very low or none. |
| Risk of Falls (Seniors) | High risk due to drowsiness and dizziness. | Very low risk. |
| Duration of Action | Relatively short-acting. | Long-acting, offering 24-hour relief. |
| Recommendation for Seniors | Avoid according to Beers Criteria. | Preferred option due to safety profile. |
For allergy relief, second-generation antihistamines like cetirizine (Zyrtec), loratadine (Claritin), or fexofenadine (Allegra) are highly recommended. For sleep issues, medical professionals suggest exploring non-drug treatments first. Cognitive Behavioral Therapy for Insomnia (CBT-I) is considered the most effective long-term treatment. Other options include improving sleep hygiene, relaxation techniques, and, in some cases, safer prescription sleep aids or supplements like melatonin, under a doctor's supervision.
Conclusion
In summary, the reason people over 65 cannot safely take Benadryl is a combination of its pharmacological properties and age-related physiological changes. The drug's potent anticholinergic effects and slower clearance in the aging body significantly increase the risk of serious side effects, including falls, confusion, and potential long-term cognitive decline. Given the availability of safer and more effective alternatives for treating allergies and promoting sleep, medical experts strongly advise seniors to avoid Benadryl and consult their healthcare provider for appropriate, low-risk options. It is essential for older adults to read all medication labels carefully and to work closely with their doctors and pharmacists to manage their health safely.
For further reading on geriatric medication safety, consult the American Geriatrics Society's Beers Criteria, available online from authoritative sources.
Outbound Link: American Geriatrics Society 2023 Beers Criteria® Update
