Key takeaways
Fexofenadine (Allegra) and diphenhydramine (Benadryl) are both antihistamines used to treat allergy symptoms, but they have some key differences. Fexofenadine (Allegra) is a second-generation antihistamine that is less likely to cause drowsiness and is available in various forms like tablets, liquid, and fast-melting tablets. It is typically taken once or twice a day and starts working in about 2 hours. On the other hand, diphenhydramine is a first-generation antihistamine that often causes significant drowsiness, making it useful as a sleep aid. It is taken every 4 to 6 hours as needed for allergies or cold symptoms and at bedtime for sleep issues. While both medications are available over-the-counter, diphenhydramine is not recommended for long-term use due to potential side effects like memory problems and confusion. For this reason, diphenhydramine should generally be avoided in adults 65 years and older. Fexofenadine is generally preferred for daily allergy management, whereas diphenhydramine is better suited for short-term allergy relief and occasional sleep problems.
