What is the most effective treatment for an allergic reaction?

Basically, antihistamines are used to treat most common cutaneous Type 1 reactions (hives), since it is the histamine release from mast cells and basophils that causes the symptoms of edema, runny nose and the itchy eyes. In life threatening situations (after calling 911), epinephrine is used to assist a person who is having a systemic anaphylaxis episode. For Type IV reactions, the standard treatment is topical corticosteroids because they are anti-inflammatory. A topical antihistamine can also be used to reduce itching.