Answer
Aug 19, 2026 - 09:53 AM
The main downside of Allegra (fexofenadine) is that, although it is one of the less-sedating antihistamines, it can still cause side effects in some people.
Potential disadvantages include headache, dizziness, nausea or stomach upset, tiredness, and occasionally drowsiness. Clinical studies of the 180-mg dose found headache was among the more commonly reported effects.
A few other things to know: fruit juices such as grapefruit, orange, or apple juice can reduce how much fexofenadine your body absorbs, so it should generally be taken with water. People with kidney disease may need a different dose.
Rarely, serious allergic reactions can occur, including swelling of the face or throat, difficulty breathing, chest tightness, or severe hives.
Compared with older antihistamines such as Benadryl, Allegra generally has the advantage of causing much less sedation, so for most people there aren't major downsides when taken at the recommended dose.
If you're asking because you're considering taking Allegra every day long-term, I can also explain the pros and cons of daily use.
