From the Guidelines
Allegra (fexofenadine) is less likely to cause sleepiness compared to older antihistamines, with studies showing no sedative properties at recommended doses 1. This is because fexofenadine has limited ability to cross the blood-brain barrier and interact with histamine receptors in the brain. Some key points to consider:
- Fexofenadine, loratadine, and desloratadine do not cause sedation at recommended doses 1
- Loratadine and desloratadine may cause sedation at doses exceeding the recommended dose 1
- Cetirizine and intranasal azelastine may cause sedation at recommended doses 1 If you're concerned about drowsiness while taking an antihistamine, Allegra is generally a good choice, especially when you need to remain alert for activities like driving or working. The standard adult dose is typically 60 mg twice daily or 180 mg once daily. If you do experience unexpected drowsiness with Allegra, consider taking it in the evening or consult your healthcare provider about alternative options. It's also important to note that while most people don't experience significant sedation with Allegra, a small percentage (approximately 1-3%) may still report some drowsiness as a side effect 1.
From the FDA Drug Label
Adverse experiences in subjects aged 12 years and older reported in placebo-controlled seasonal allergic rhinitis clinical trials in the United States Twice- daily dosing with fexofenadine capsulesat rates of greater than 1% Adverse experienceFexofenadine 60 mgTwice Daily(n=679)PlaceboTwice Daily(n=671) ... Drowsiness1.3%0. 9%
Allegra (fexofenadine) can cause sleepiness, as indicated by the reported adverse experience of drowsiness in 1.3% of subjects taking the recommended daily dose of 60 mg twice daily, compared to 0.9% of subjects taking placebo 2.
- The incidence of drowsiness was similar across subgroups defined by age, gender, and race.
- Drowsiness was not dose-related.
- The frequency of drowsiness was slightly higher in subjects taking fexofenadine compared to those taking placebo.
From the Research
Allegra and Sleepiness
- Allegra, also known as fexofenadine, is a second-generation antihistamine used to treat allergic rhinitis and urticaria.
- Studies have shown that fexofenadine is non-sedating due to its decreased blood-brain barrier permeability 3, 4.
- A systematic review and meta-analysis of randomized controlled trials found that fexofenadine produced significantly lower sedative effects compared to first-generation antihistamines and some second-generation antihistamines 5.
- Another study found that new-generation antihistamines, including fexofenadine, reduced sleep latency and dream anxiety, but did not increase daytime sleepiness 6.
- A review of the clinical experience with fexofenadine over 25 years found that it has a wide therapeutic window and is not associated with any sedative effects, even at higher than recommended doses 7.
Comparison to Other Antihistamines
- First-generation antihistamines, such as pheniramine, can cause sedation and impair cognitive function and psychomotor performance 4, 6.
- Second-generation antihistamines, such as cetirizine and desloratadine, may also cause sedative effects, although to a lesser extent than first-generation antihistamines 4, 5.
- Fexofenadine has been found to have a favorable safety profile compared to other antihistamines, with fewer sedative effects and less impact on cognitive and psychomotor function 3, 5, 7.