Allegra is a prescription drug manufactured by Aventis Pharmaceuticals used in the treatment of allergies. It is an antihistamine which is used to reduce the level of histamine in human body. Histamine is a chemical found naturally in the human body which is responsible for the many allergic symptoms. These allergic symptoms include conditions like itching, running nose, sneezing, watery eyes, irritation, and other things. 

Allegra should never be taken with fruit juice or antacids, which make it harder for the body to absorb the medication. It should always be taken with drinking water. Disclose your medical history and the kind of medicines you take to your doctor completely, as some of the drugs you take can react with Allegra.  If you are shopping around for Allegra you can find them being sold extensively at retail pharmacies and online pharmacies. You can also find plenty of information about the drug by going through these online resources. It is always recommended that you consult your physician or pharmacist before taking Allegra.

Allegra has less serious side effects like nausea, vomiting, headache, pain, drowsiness, and upset stomach which could be taken care of by the doctor. You can continue with the medication in such cases. But if you happen to have any of these side effects like fever, chills, flu, difficulty in breathing, hives, swollen face or lips, it is recommended in such cases that the medication should be stopped with immediate effect. People suffering from such side effects should also immediately seek medical attention.