Most common side effects in adults include: stomach upset, diarrhea, tiredness. Some common side effects in children include fever and rash. In some cases these can be serious but are usually not treated as such. These should always be reported to your doctor though if they become severe or persist for over a week.
How much allegra do I take?
The recommended daily dose is 50mg (1 tablet) per day for adults and 25mg (1 tablet) per day for children under 12 years of age.