Anti-allergic agents are medications used to treat allergic reactions. Anti-allergic agents have existed since 3000 B.C in countries such as China and Egypt. It was not until 1933 when antihistamines, the first type of anti-allergic agents, were developed.[1] Common allergic diseases include allergic rhinitis, allergic asthma and atopic dermatitis with varying symptoms, including runny nose, watery eyes, itchiness, coughing, and shortness of breath. More than one-third of the world's population is currently being affected by one or more allergic conditions.[2]
Commonly used anti-allergic agents include antihistamines, decongestants, corticosteroids, leukotriene pathway modifiers and mast cell stabilizers. Antihistamines and decongestants are generally the first-line treatment in mild to moderate allergic reactions. Corticosteroids are generally indicated for moderate cases. In severe cases, adrenaline is used to reduce swelling and aid breathing. Allergen immunotherapy is an alternative treatment considered in some patients, with a success rate of 80%-90% in reducing symptoms,[3] but requiring a much longer duration of therapy. The choice of medications depends on the disease to be treated, its severity and patient factors.