Treatment of allergic rhinitis/conjunctivitis and allergic asthma is aimed to alleviate symptoms. Allergen avoidance and pharmacotherapy are usually first-line treatments. When both techniques fail to offer symptom control, immunotherapy; whether subcutaneous or sublingual; offers the only chance for a cure by modifying the immunologic response of the patient. A shift from a Th2 to Th1 response, increased production of IL-10, and increased Treg activity remain the proposed mechanisms by which immunotherapy works within the human body.