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Living With Allergies: A Glossary

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

Allergist. A doctor who diagnoses and treats allergy-related conditions.

Recommended Related to Allergies

Managing Allergies at School

Does your child miss school due to allergies? If so, you're not alone. Seasonal allergies are believed to affect as many as 40% of U.S. children. On any given day, about 10,000 of those children miss school because of their allergies. That's a total of more than 2 million lost school days every year. Even if your child doesn't miss school, allergies can get in the way of a productive school day, so managing allergies at school is an important part of caring for your child's health.

Read the Managing Allergies at School article > >

Anaphylaxis. A life-threatening 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.

Asthma. A chronic inflammatory lung disease. Symptoms include breathing problems, fatigue, headaches, and cough. Asthma is often triggered by allergens, infection, exercise, cold air, or other factors.

Atopic dermatitis. See "Eczema."

Bronchitis. An inflammation of the lung's airways. Symptoms include a persistent cough and phlegm. Bronchitis is usually seen in smokers and in places with high pollution.

Contact dermatitis. An allergic reaction that occurs after skin comes in contact with an allergen such as poison ivy, washing powders, perfumes, or other irritants.

Dander. Small pieces of skin shed by an animal, similar to human dandruff. Proteins found in dander are the major causes of pet allergies.

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

Eczema. Chronic inflammation that causes a skin rash. Eczema may be a reaction to an allergen. Symptoms include itching, crusting, blisters, and scaling. Atopic dermatitis is a type of eczema that worsens after exposure to an allergen.

Epinephrine. A drug used to immediately treat severe allergic reactions. Also known as adrenaline. Epinephrine causes an increase in blood pressure and heart rate.

Inflammation. Redness, swelling, heat, and pain in a tissue. Such symptoms can be the result of an allergic reaction in the nose, lungs, or skin.

Hay fever. Also known as allergic rhinitis. Hay fever is an inflammation of the mucus membranes in the nose. Hay fever often results from allergies to pollen, dust, certain foods, and other substances. Symptoms include sneezing, itching, runny nose, and nasal congestion.

Histamine. A chemical released by the immune system after it's exposed to an allergen. It causes tissues to become swollen, inflamed, itchy, and red.

Hives. An allergic reaction of the skin. Symptoms include itchy, swollen, red bumps that appear suddenly. Hives can show up anywhere, including lips, tongue, and ears. Also known as urticaria.

Latex allergy. An allergy to the latex proteins found in many rubber or latex products, including rubber gloves, tubing, and rubber bands, for example.

Nasal spray. Over-the-counter or prescription drugs that can treat and prevent nasal symptoms such as congestion and runny nose.

Occupational asthma. Breathing problems caused by potentially harmful substances found where you work, including fumes, dust, gases, and other irritants. This may also be caused by flour, known as "baker’s asthma." 

Pollen. A central cause of many allergic reactions, pollen is a fine, powdery substance released by trees, grasses, weeds, and flowering plants.

Rhinitis. See "Hay Fever."

Sinuses. Mucus-membrane-lined air pockets located behind the eyes and nose.

Sinusitis. Inflammation or infection of the membranes lining the sinuses. Symptoms include pain and pressure with a runny or stuffy nose.

Urticaria. See "Hives."

WebMD Medical Reference

Reviewed by Kimball Johnson, MD on August 02, 2012

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