Allergies : Articles

An allergy is an exaggerated immune response or reaction to substances that are generally not harmful. See also: Allergic conjunctivitis; Allergic reactions; Allergy testing; Allergy to mold, dander, dust; Atopic dermatitis (eczema; Contact dermatitis; Drug allergies; Food allergies; Hay fever (allergic rhinitis.

Allergies are abnormal reactions of the immune system that occur in response to otherwise harmless substances.

Physical allergies are allergic reactions to cold, sunlight, heat, or minor injury.

Allergies are abnormal reactions of the immune system that occur in response to otherwise harmless substances.

Allergies are abnormal reactions of the immune system that occur in response to otherwise harmless substances.

Allergies are abnormal reactions of the immune system that occur in response to otherwise harmless substances.

Dust mites are perhaps the most common cause of nasal allergies. These mites are microscopic organisms that live in bedding, upholstered furniture, and carpets. They thrive in warm, humid conditions.

Food allergies affect approximately 3 percent of children and 1 percent of adults in the United States. It is estimated that an even larger percentage of the population experiences problems with food intolerance. Worldwide, adverse reactions to food constitute a significant public health issue.

A hypersensitive response by the immune system to a foreign substance that is ordinarily harmless. Allergies account for more office visits to pediatricians than any other ailment, besides the common cold, and are responsible for more missed school days than any other medical problem. It is thought that at least one out of every five children has an allergy of some kind. Allergies are often inherited—a child with one allergic parent has a 25-35% chance of developing allergies, and the likelihood rises to between 50 and 65% if both parents have allergies. The substances that cause allergies—such as dust or pollen—are known as allergens (or antigens). In persons with special sensitivities, they produce elevated levels of immunoglobulin E (IgE) antibodies, which in turn unleash chemicals called histamines that produce allergic reactions. Common allergens include pollen, animal dander, house dust, chemicals, feathers, and a number of different foods. Allergy symptoms affect a number of different body organs. Skin reactions take a variety of forms—including hives, eczema, and other rashes—but whatever their appearance they are almost always accompanied by acute itching. Respiratory symptoms include a runny, congested, or itchy nose and post-nasal drip, as well as the coughing, wheezing, and shortness of breath that characterize asthma. Eyes may itch, redden, swell, and water. Other allergic symptoms include itching on the roof of the mouth, clogged ears and gastrointestinal problems (nausea, vomiting, diarrhea). Allergies are usually diagnosed either through observation of symptoms, skin tests, or elimination diets, in which different foods are eliminated from the diet in order to discover which ones are causing the problem. Allergy treatment can be grouped into three broad categories. The simplest is to avoid contact with known allergens. Depending on the type of allergy, this may involve eliminating certain foods from the diet, keeping dust under control by cleaning or by using an air cleaner, making adjustments in pet ownership, or removing trouble-causing items such as feather pillows. The second type of treatment consists of medications, such as antihistamines, that alleviate the symptoms of allergic reactions. A final method is desensitization, more familiarly known as allergy shots, a treatment that exposes an allergic person to gradually increasing amounts of certain allergens over an extended time period in hopes of eliminating or reducing sensitivity to them.