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Allergy and Allergies Glossary

Allergen. A foreign substance the body perceives as harmful, triggering an allergic reaction.

Allergist. A doctor who specializes in the treatment of allergy-related conditions.

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Anaphylaxis. A life-threatening medical emergency. It is a severe allergic reaction involving the entire body, most frequently the respiratory system, making it difficult to breathe.  Anaphylaxis requires immediate medical attention.

Antihistamines. These drugs block histamine -- a chemical the body releases during an allergic reaction -- reducing symptoms such as itching, sneezing, and runny nose.

Anti-inflammatory drugs. Medications that reduce the symptoms of inflammation, such as pain, swelling, and redness.

Bronchodilator medication. These drugs relax tight muscles around lung airways, making it easier to breathe.

Bronchitis. An inflammation of the lung airways. Symptoms include a persistent cough and phlegm. Bronchitis is usually seen in smokers and in places with high air pollution. It can also be caused by infection, both viral and bacterial.

Corticosteroids. Steroid containtin anti-inflammatory drugs that treat the itching and swelling associated with some allergic reactions.

Decongestants. Medications that shrink swollen nasal membranes, decreasing congestion and mucus, making it easier to breathe.

Elimination diet. A diet that first eliminates foods suspected of causing an allergic reaction, then reintroduces them one at a time so the offending food can be found.

Epinephrine. A medication used to immediately treat severe allergic reactions. Epinephrine, also known as adrenaline, relaxes tightened muscles around the airways, improving breathing.

HEPA. High-efficiency particulate air (HEPA). A HEPA filter removes airborne particles 0.3 microns or larger by pushing them through screens with microscopic pores.

Histamine. A chemical released by the immune system after it's exposed to an allergen. Histamine causes allergy symptoms such as runny nose, sneezing, and itching.

Hypoallergenic. Products designed to contain as few allergens as possible.

Immunotherapy. Commonly called allergy shots, a series of increasing exposures to an allergen (usually by injection but drops may also be placed under the tongue) designed to raise your tolerance to an allergen such as pollen, dander, or insect stings, and even some foods. The FDA has also approved under-the-tongue immunotherapy tablets that treat hay fever. 

Inhaled steroids. Drugs that decrease swelling and mucus production in lung airways. Also called inhaled corticosteroids.

Leukotriene inhibitors. Medications that block leukotrienes -- chemicals which cause tightening of airways as well as mucus and fluid production.

Nasal spray. Over-the-counter products or prescription drugs that are sprayed into the nose to treat and prevent nasal symptoms such as congestion and runny nose.

Nasal wash. The act of cleaning nasal and sinus passages; most commonly with salt water but sometimes with medications. Also called nasal irrigation.

Nebulizer. A device that changes liquid medication into a fine, inhalable mist. Nebulizers make medication easier to take for some individuals, such as infants or seniors.

Patch tests. A test that helps identify substances to which a person may be allergic. Suspected allergens are applied to unbroken skin, then observed to see if an allergic reaction occurs.

RAST (Radioallergosorbent Test). A blood test that helps identify substances causing a person's allergy symptoms.

Sensitization. Development of an allergic reaction to a substance over time rather than immediate.  

Skin testing. A test where a small bit of allergen is scratched on the skin. An allergy to the substance results in swelling at the site, usually within 15 minutes to 20 minutes. Also called skin prick test.

WebMD Medical Reference

Reviewed by Luqman Seidu, MD on May 19, 2014

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