From the Guidelines
Using Benadryl (diphenhydramine) continuously for 9 months is not recommended due to the risk of cognitive decline, particularly in the elderly, and other adverse effects such as sedation, dry mouth, and constipation. According to the most recent study 1, sedating H1 antihistamines like diphenhydramine can cause cognitive decline, especially in older adults. The study suggests that nonsedating H1 histamines are generally preferred and can be increased to 2 to 4 times the standard dose.
Risks Associated with Long-term Use of Benadryl
- Cognitive decline, particularly in the elderly 1
- Sedation and performance impairment 1
- Dry mouth, constipation, and other anticholinergic effects 1
- Increased risk of falls and fractures in older adults 1
Safer Alternatives for Long-term Use
- Second-generation antihistamines like cetirizine (Zyrtec) or loratadine (Claritin) for allergies, which cause less drowsiness and are approved for daily, long-term use 1
- Other medications specifically designed for long-term use with better safety profiles, which can be recommended by a healthcare provider after discussing the underlying condition requiring treatment.
It is essential to consult with a healthcare provider before using Benadryl for an extended period to discuss the underlying condition and explore safer alternatives. The provider can help determine the best course of treatment and minimize the risk of adverse effects.
From the Research
Safety of Benadryl for 9 Months
- There are no studies that directly address the safety of using Benadryl (diphenhydramine) for 9 months 2, 3, 4, 5, 6.
- However, studies have shown that diphenhydramine can cause sedation, cognitive impairment, and psychomotor performance impairment, especially in the elderly and with long-term use 3, 4, 5, 6.
- A systematic review of over-the-counter sleep aids found that diphenhydramine had a statistically significant increase in sedation and decrease in number of awakenings, but was not shown to be any less or more safe than compared products 3.
- Another study found that diphenhydramine impaired cognitive performance, caused fatigue and sleepiness, and lowered motivation, especially after the initial dose and on day 3 of administration 4.
- A meta-analysis of sedation and performance impairment of diphenhydramine and second-generation antihistamines found that diphenhydramine impaired performance relative to placebo control and second-generation antihistamines, but the average sedating effect was modest 6.
Potential Risks and Considerations
- Long-term use of diphenhydramine can lead to tolerance, dependence, and withdrawal effects 2.
- Diphenhydramine can cause psychomotor impairment, especially in the elderly, and occasionally paradoxical excitement 2.
- Patients taking diphenhydramine may be at risk of lapses and significant errors that may lead to potential hazards and decreased work productivity 4.