10 Allergy Terms You Should Know

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A common substance in the environment that does not bother most people, but that your body perceives as a threat to your health.  As a result, your body mounts a defense called an allergic reaction, causing symptoms such as wheezing, chest tightness, shortness of breath and cough.

Indoor Allergies

A type of sensitivity to allergens generally found indoors, such as pet dander and urine, insect allergens, indoor mold spores and dust mites. Indoor allergies are also known as year-round allergies, because it is difficult to escape exposure to indoor allergens at all times.

Outdoor Allergies

A type of sensitivity to allergens that originate outdoors, such as tree, grass and weed pollens, outdoor mold spores and certain stinging insects. Outdoor allergies are considered seasonal, because the allergens are usually only in the air at certain times each year, particularly during the spring, summer and early fall.

Hay fever

A laymen’s term for seasonal (outdoor) allergies or allergic rhinitis. It is a misleading term, because the condition it stands for does not involve an allergy to hay, nor does it produce fever as a symptom.


Tiny, egg-shaped cells in flowering plants that are too small to be seen with the naked eye and that are easily carried on the wind. Pollen is not harmful to most people. But when you have allergies, your immune system interprets pollen spores as dangerous invaders and mounts a defense system that results in your allergy symptoms. Pollen counts vary greatly through the year, depending on type.


An allergy treatment where you are exposed to tiny, but slowly increasing amounts of the allergens you are allergic to. The aim is to gradually decrease your sensitivity to the allergen over time. Immunotherapy is usually given as in injection given on a weekly basis over a year or two. There is also a form called sublingual, which are drops placed under the tongue that is used less often.


An inflammation of the lining of the nasal passages that occurs in people with allergies. It can also occur with environmental irritants, infections and other causes. Rhinitis causes the allergy symptoms of runny nose, stuffy nasal passages, post-nasal drip and sneezing.


A rare, but severe, allergic reaction that can be life-threatening and that has effects throughout the body. It is usually in response to stinging insects, certain medications or foods. Symptoms include shortness of breath, wheezing, hives and a drop in blood pressure. Immediate emergency treatment is essential in preventing death.


A type of medication that blocks the effect of histamine, a chemical in the body that triggers allergic reactions when you are exposed to an allergen to which you are sensitive. This type of medicine is an essential tool in managing allergies and preventing allergy symptoms.


Tiny scales that are shed from the skin of pets such as dogs and cats and that people are often allergic to. Dander can get lodged in the pet’s hair, but it is the dander that is the allergen, not the hair. These scales also float in the air and land in rugs, bedding, fabric furniture and household dust.