Allergy Terms Glossary

Reviewed by Sabrina Felson, MD on March 06, 2020

Allergen: A substance the body thinks is harmful, which triggers an allergic reaction.

Allergist: A doctor who specializes in allergy-related conditions.

Anaphylaxis: A severe, life-threatening reaction marked by trouble breathing, a drop in blood pressure, along with hives, stomach cramps, or belly pain. In severe cases, a person will go into shock. If anaphylactic shock isn't treated immediately, it can be fatal.

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

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

Bronchodilator medication: Drugs that relax tight muscles around lung airways. This makes it easier to breathe.

Corticosteroids: A steroid that contains anti-inflammatory drugs that treat the itching and swelling tied to some allergic reactions.

Decongestants: Medications that shrink swollen nasal membranes, which eases congestion and mucus, and makes it easier to breathe.

Desensitization: When the bosy is exposed gradually to a small amount of an allergin to help build up immunity to it.


Elimination diet: A plan that has you stop eating foods that might be causing your allergic reactions and then introduces them back one at a time to identify the problem food or foods.

Epinephrine: A medication that treats severe allergic reactions immediately. Also known as adrenaline, this relaxes tightened muscles around the airways, which makes it easier to breathe.

HEPA filter: High-efficiency particulate air filter. This type of filter removes tiny airborne particles 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 that have as few allergens as possible.

Immunotherapy: Your doctor may call these “allergy shots.” They slowly expose you to an allergen (usually by injection, but drops may also be placed under the tongue). They’re meant to raise your tolerance to allergy-causers like pollen, dander, insect stings, or some foods. The FDA has also approved under-the-tongue immunotherapy tablets that treat hay fever.


Inhaled steroids: Drugs that curb swelling and mucus in lung airways. You may hear them called inhaled corticosteroids.

Leukotriene inhibitors: Medications used to treat asthma that block chemicals that tighten airways, make mucus, and cause swelling in the lungs.

Nasal spray: Over-the-counter products or prescription drugs you spray into your nose to treat and prevent nasal symptoms like congestion and nose running.

Nasal wash: A way to clean nasal and sinus passages, usually with warm saltwater but sometimes with medicines. You may hear it called nasal irrigation.

Nebulizer: A device that turns liquid medicine into a mist you inhale. Nebulizers make medication easier to take for some people, like infants or seniors.

Patch tests: These help identify what you may be allergic to. Possible triggers are put on unbroken skin to see if an allergic reaction happens.

RAST (Radioallergosorbent Test). A blood test that helps identify things that cause a person's allergies.

Sensitization: Development of a reaction to a substance over time rather than immediately.

Skin testing: A procedure in which a small bit of allergen is scratched on your skin. If you’re allergic, that area of your skin swells. It usually takes between 15 and 20 minutes. You may hear it called a skin prick test.

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SOURCES: 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." 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." News release, FDA.

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