allergy /al″ərjē/ [Gk, allos, other, ergein, to work] , a hypersensitive reaction to common, often intrinsically harmless, substances most of which are environmental. More than 50 million Americans have allergic reactions to airborne or inhaled allergens, such as cigarette smoke, house dust, and pollens. Symptoms of mild allergies, such as those associated with rhinitis, conjunctivitis, and urticaria, can be suppressed by antihistamines, with glucocorticoids administered as supplements to primary therapy. Severe allergic reactions, such as anaphylaxis and angioedema of the glottis, can cause systemic shock and death and commonly require immediate therapy with subcutaneous epinephrine or IV steroids, such as dexamethasone. See also allergic reaction, allergy testing.
