Living With Allergies: A Glossary

Reviewed by Nayana Ambardekar, MD on January 25, 2020

Allergen: A substance the body sees as harmful. In response, an allergic reaction is triggered.

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

Anaphylaxis: A life-threatening allergic reaction involving the entire body. It requires immediate medical attention.

Antihistamines: Drugs that block histamine, a chemical the body releases during an allergic reaction. These meds ease symptoms like itching, sneezing, and a runny nose.

Asthma: A long-term inflammatory lung disease. Symptoms include breathing problems, chest tightness, fatigue, wheezing, and coughing. The triggers include allergens, an infection, exercise, cold air, or other things.

Atopic dermatitis: See "Eczema."

Bronchitis: An inflammation of the lung's airways. Symptoms include a persistent cough and phlegm that lasts at least 5 days. Acute bronchitis can last up to 3 weeks and is typically caused by a virus. Chronic bronchitis is a type of lung disease that frequently affects smokers and people who live in places with lots of pollution.

Contact dermatitis: An allergic reaction that happens 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 in dander are major causes of pet allergies.

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

Eczema: Chronic inflammation that causes a skin rash. It may be a reaction to an allergen. Symptoms may include itching, crusting, blisters, and scaling. Atopic dermatitis is a type of eczema that gets worse after you come in contact with 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 mucous membranes in the nose. The condition often stems from allergies to pollen, dust, certain foods, and other substances. Symptoms include sneezing, itching, a 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: Raised, often itchy, red bumps on the surface of the skin. Angioedema is swelling of the deeper tissue that sometimes occurs with hives and can affect the lips, tongue, and ears. 

Latex allergy: An allergy to the proteins 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 like congestion and a 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 main cause of many allergic reactions, pollen is a fine, powdery substance released by trees, grasses, weeds, and flowering plants.

Rhinitis: See "Hay Fever."

Sinuses. Hollow spaces within the bones around the nose, cheeks, and eyes.

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

WebMD Medical Reference


American College of Allergy, Asthma & Immunology: "Allergy-Immunology Glossary." American Academy of Allergy, Asthma and Immunology: "Glossary." Asthma and Allergy Foundation of America: "Glossary of Allergy Terms" and "What are the Symptoms of Asthma." Cleveland Clinic Health System: "Allergy Glossary of Terms." WebMD: "Asthma Glossary of Terms." WebMD Medical Reference: "Asthma, Steroids, and Other Anti-Inflammatory Drugs." eMedicineHealth: "Sinus Infection Glossary." UpToDate: "Acute Bronchitis in Adults." 

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