Allergies are a fact of life for many people—in fact, 20 percent of Americans must live with some type of allergic reaction. An allergy is an abnormal response to a typically nontoxic substance. During an allergic reaction, a person’s immune system responds to a substance—perhaps pollen, dust mites or a type of food, such as gluten or nuts—as if it were a harmful invader. Allergic antibodies, or IgE, flood the body with histamine and other chemicals, causing allergy symptoms, such as sneezing, difficulty breathing, cramps and even vomiting. Allergies can occur at any time, but are more common during childhood or young adulthood, and allergies are believed to run in families.
Allergic rhinitis, or hay fever, is a mild allergy highly prevalent in the U.S. population. Seasonal allergies are triggered mostly by pollen (tree, grass, ragweed). Yearround allergies are often caused by dust mites, mold, pet dander and feathers. Symptoms include sneezing, runny nose and burning eyes. People with hay fever are more likely to also have asthma and eczema (allergic dermatitis).
Food allergies are increasingly common, especially among U.S. children. The most common food allergens are milk, egg, peanut, tree nuts, fish, shellfish, soy and wheat. Some allergens may be outgrown, but not others, like peanuts and shellfish. Celiac disease (CD) isa serious hereditary autoimmune condition triggered by gluten, a protein in wheat and other grains, that damages the small intestines and can lead to nutrient malabsorption and comprised immunity. Food intolerances, such as gluten intolerance or lactose intolerance, are less serious, but cause intestinal discomfort.
Other allergies include hives, drug allergies (such as penicillin), insect allergies (such as bees). Anaphlaxis is a severe, potentially life-threatening allergic response to a bee sting or other allergen.