Allergic rhinitis is an inflammation of the nasal membranes mediated by an allergic reaction. This is a very common condition, affecting about 20% of the population. The condition is characterized by inflammation of the mucous membranes of the nose, eyes, Eustachian tubes, middle ears, sinuses, and pharynx. The hypersensitive immune reaction is triggered by an IgE response to an environmental allergen. The IgE response enables the release of various immune system mediators, including histamine, tryptase, chymase, kinins, heparins, leukotrienes, and prostaglandins that are responsible for the characteristic clinical features of the condition. Major signs and symptoms include repetitive sneezing, runny nose, nasal congestion, nasal itching, post-nasal drip, itchy eyes, ears, nose or throat, sore throat, generalized fatigue, and impaired smell. The most common form of allergic rhinitis is hay fever, caused by an allergic reaction to pollen. Some forms of the condition are seasonal, and occur only during those times of the year when the corresponding allergen is present. For instance, tree, grass and ragweed pollen allergies are more common during hot, dry, and windy days. Similarly, mold spores are higher in early spring, late summer, and early fall. Other allergens like dust mites, cockroaches, and animal dander can be found all-year round.
A study of the clinical features is the first step towards diagnosing this condition. Confirmation of the diagnosis involves a skin test (scratch, patch, or other tests) with the allergen. The best form of treatment is to avoid the allergen. Drugs that are commonly used to treat an allergic attack include short and longer-acting anti-histamines, nasal corticosteroid sprays, and decongestants. In cases where it is impossible to avoid the allergen, allergy shots may be recommended, which slowly de-sensitize the body against the allergen. In children, the immune system may by itself become less sensitive to the allergen as time passes.