From the Guidelines
Benadryl (diphenhydramine) and Vistaril (hydroxyzine) are both first-generation antihistamines with significant potential to cause sedation, performance impairment, and anticholinergic effects, but they have different durations of action and side effect profiles. The main difference between the two medications is their duration of action and their side effect profiles.
- Vistaril has a longer duration of action (6-8 hours) compared to Benadryl (4-6 hours) 1.
- Benadryl is more commonly used for acute allergic reactions and as a sleep aid, while Vistaril is often prescribed for anxiety, tension, and as a pre-surgical sedative.
- Dosing for Benadryl typically ranges from 25-50mg every 4-6 hours (maximum 300mg daily), while Vistaril is usually prescribed at 25-100mg 3-4 times daily for anxiety 1.
- Vistaril tends to cause less drowsiness than Benadryl and has fewer anticholinergic side effects (dry mouth, urinary retention, confusion) 1.
- Both medications work by blocking histamine receptors in the brain, but Vistaril also affects serotonin pathways, which contributes to its anti-anxiety effects 1.
- Neither should be combined with alcohol or other central nervous system depressants, and both require caution in elderly patients and those with certain medical conditions like glaucoma or prostate problems 1. It's worth noting that second-generation antihistamines are generally preferred over first-generation antihistamines like Benadryl and Vistaril due to their lower likelihood of adverse effects 1.
From the Research
Difference between Diphenhydramine (Benadryl) and Hydroxyzine (Vistaril)
- Diphenhydramine and Hydroxyzine are both first-generation antihistamines, which can have adverse effects on the central nervous system, such as sedation and impairment of cognitive function 2, 3.
- Both medications are used to treat allergic reactions, but they have different properties and side effects 4, 5.
- Hydroxyzine is sometimes considered more potent than Diphenhydramine, but both can cause sedation and anticholinergic side effects, such as dry mouth 4, 5.
- Newer generation antihistamines, such as cetirizine, desloratadine, and fexofenadine, are considered safer and more effective than first-generation antihistamines like Diphenhydramine and Hydroxyzine, with less sedation and impairment 2, 3, 6.
Side Effects and Efficacy
- Diphenhydramine can impair psychomotor performance and cognitive function, and has a faster onset of action compared to some newer antihistamines 2.
- Hydroxyzine is associated with anticholinergic and CNS effects, such as drowsiness and sedation, which can pose risks to patients, especially when driving 5.
- Newer generation antihistamines have improved potency and efficacy, and are recommended as first-line treatment for mild allergic rhinitis and acute and chronic urticaria 3, 6.
Recommendations
- The Canadian Society of Allergy Clinical Immunology recommends that newer generation antihistamines should be preferred over first-generation antihistamines like Diphenhydramine and Hydroxyzine for the treatment of allergic rhino-conjunctivitis and urticaria 3.
- Health professionals and the public should be educated about the benefits and risks of different antihistamines, and patients should be informed about the potential side effects of first-generation antihistamines like Diphenhydramine and Hydroxyzine 3, 6.