Adrenaline - see epinephrine.
Allergen - the substance that triggers an allergic reaction.
Allergy - an acquired, abnormal immune response to a substance that can cause a broad range of inflammatory reactions.
Anaphylaxis (also called anaphylactic shock) - a sudden, severe, potentially life-threatening allergic reaction caused by food allergy, insect stings or medications. Symptoms can include hives, swelling (especially of the lips and face), difficulty breathing (either because of swelling in the throat or an asthmatic reaction), vomiting, diarrhea, cramping and a fall in blood pressure.
Antibody (also called an immunoglobulin) - a complex protein that is manufactured by lymphocytes to neutralize or destroy an antigen or foreign protein. Many types of antibodies are protective; however, inappropriate or excessive formation of antibodies may lead to illness.
Antigen - a substance that can trigger an immune response causing the production of antibodies as part of the body's defense against infection and disease.
Antihistamine drugs - a group of drugs that block the effects of histamine, a chemical released in body fluids during an allergic reaction.
Anti-inflammatory drugs - drugs that reduce the symptoms and signs of inflammation.
Asthma - a chronic, inflammatory lung disease characterized by recurrent breathing problems usually triggered by allergens (infection, exercise, cold air, and other factors may also be triggers).
Bronchitis - an inflammation of the mucous membranes of the bronchial tubes, causing a persistent cough that produces considerable quantities of sputum (phlegm).
Bronchodilators - a group of drugs that widen the airways in the lungs.
Bronchus - any of the larger air passages that connect the trachea to the lungs.
Celiac disease (also called celiac sprue or gluten sensitive enteropathy) - a sensitivity to gluten, a wheat protein. Individuals with this disease must avoid gluten-containing grains, which include all forms of wheat, oats, barley, and rye.
Contact dermatitis - a rash or an inflammation of the skin caused by contact with various substances.
Corticosteroids - a group of anti-inflammatory drugs similar to the natural corticosteroid hormones produced by the adrenal glands.
Digestive system - the group of organs that break down foods into chemical components that the body can absorb and use for energy, and for building and repairing cells and tissues.
Eczema - inflammation of the skin, usually causing itching and sometimes accompanied by crusting, scaling, or blisters.
Epinephrine - one of two chemicals (the other is norepinephrine) released by the adrenal gland that increases the speed and force of heart beats. It dilates the airways to improve breathing and narrows blood vessels in the skin and intestine so that an increased flow of blood reaches the muscles and allows them to cope with the demands of exercise.
Extrinsic asthma - asthma that is triggered by an allergic reaction, usually to something that is inhaled.
Food intolerance - an adverse food-induced reaction that does not involve the immune system. Lactose intolerance is an example.
Gluten sensitive enteropathy (Also called celiac sprue or celiac disease.) - a sensitivity to gluten, a wheat protein. Individuals with this disease must avoid gluten-containing grains, which include all forms of wheat, oats, barley and rye.
Hay fever - see rhinitis.
Histamine - a chemical present in cells throughout the body that is released during an allergic reaction and one of the substances responsible for the symptoms of inflammation.
Hives - see urticaria.
Immune system - a collection of cells and proteins that works to protect the body from potentially harmful, infectious microorganisms, such as bacteria, viruses, and fungi.
Immunoglobulin E (IgE) - a type of antibody, formed to protect the body from infection, which attaches to mast cells in the respiratory and intestinal tracts and may cause allergic rhinitis, asthma, or eczema.
Immunoglobulins - antibodies or proteins found in blood and tissue fluids produced by cells of the immune system to bind to substances in the body that are recognized as foreign antigens. Immunoglobulins sometimes bind to antigens that are not necessarily a threat to health and provoke an allergic reaction.
Immunotherapy - treatment of allergy to substances such as pollens, house dust mites, fungi, and stinging insect venom involving giving gradually increasing doses of the substance, or allergen, to which the person is allergic.
Inflammation - redness, swelling, heat, and pain in a tissue due to chemical or physical injury, infection, or allergic reactions in the nose, lungs, and skin.
Intrinsic asthma - asthma that has no apparent external cause.
Lactose intolerance - a food intolerance not allergy. A person with lactose intolerance lacks an enzyme that is needed to digest milk sugar, which causes symptoms such as gas, bloating, and abdominal pain.
Lymphocyte - any one of a group of white blood cells of crucial importance to the adaptive part of the body's immune system.
Mast cells - cells, which synthesize and store histamines, found in most body tissues, particularly just below the epithelial surfaces, serous cavities and around blood vessels. In an allergic response, an allergen stimulates the release of antibodies, which attach themselves to mast cells.
Peak flow meter (PFM) - a device used to measure the fastest speed in which a person can blow air out of the lungs. During an asthma or other respiratory flare up, the large airways in the lungs slowly begin to narrow. This will slow the speed of air leaving the lungs and can be measured by a PFM. This measurement is very important in evaluating how well or how poorly the disease is being controlled.
Prick skin test - a test to determine if a patient is allergic to certain substances. A physician places a drop of the substance being tested on the patient's forearm or back and pricks the skin with a needle, allowing a tiny amount to enter the skin. If the patient is allergic to the substance, a wheal (mosquito bite-like bump) will form at the site within about 15 minutes.
RAST (RadioAllergoSorbent Test, a trademark of Pharmacia Diagnostics) - a laboratory test used to detect IgE antibodies to specific allergens. A RAST requires a blood sample, which is sent to a medical laboratory where tests are done with specific foods to determine whether the patient has IgE antibodies to that food.
Respiratory system - the group of organs responsible for carrying oxygen from the air to the bloodstream and for expelling carbon dioxide.
Rhinitis - an inflammation of the mucous membrane that lines the nose, often due to allergy to pollen, dust or other airborne substances, which causes sneezing, itching, a runny nose and nasal congestion.
Sinus (paranasal sinuses) - air cavities within the facial bones, lined by mucous membranes similar to those in other parts of the airways.
Sinusitis - inflammation of the membranes lining the facial sinuses, often caused by bacterial or viral infection, or allergic reaction.
Urticaria - a skin condition, commonly known as hives, characterized by the development of itchy, raised red lumps surrounded by an area.