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.

Anaphylaxis. A life-threatening medical emergency. It is a severe allergic reaction involving the entire body. 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.

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.

Corticosteroids. 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. Also known as allergy shots. A series of injections designed to raise your tolerance to an allergen such as pollen, dander, or insect stings.

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 or prescription drugs that treat and prevent nasal allergy symptoms such as congestion and runny nose.

Nasal wash. The act of cleaning nasal and sinus passages with sterile salt water. 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, over time, of an allergic reaction to a substance. The reverse of drug tolerance.

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