Although there are number of different treatments available for allergies, most if not all only treat the symptoms and not the root cause of the problem. Well-known antihistamines such as Benadryl a.k.a. diphenhydramine, Claritin also called loratadine together with decongestant sprays such as Nasonex, are available by prescription or over the counter and do a good job in providing relief for allergy sufferers. Allergic reactions are ultimately caused by an overactive immune system and a treatment known as allergy immunotherapy attempts to offer a longer-term solution by changing how the immune system responds to various allergens. It is, in effect, a form of vaccination better known as allergy shots