Get emergency medical help if you have any of these signs of an allergic reaction to Allegra: hives; difficulty breathing; swelling of your face, lips, tongue, or throat. Stop taking Allegra and call your doctor if you have fever, chills, body aches, cough, or other flu symptoms.
Less serious Allegra side effects may include:
nausea, diarrhea, upset stomach;
menstrual cramps;
drowsiness, tired feeling;
headache; or
muscle or back pain.
This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.
 Allegra side effects (more detail)
