Allergies Glossary

Reviewed by: HU Medical Review Board



Any substance that causes an allergic reaction.1

Allergic reaction

A response by the body when it comes into contact with an allergen. An allergen is something the immune system sees as a danger.1

Allergic rhinitis

See hay fever.

Allergic shiner

Dark rings or bags under the eyes caused by an allergy.1


A doctor who specializes in diagnosing and treating people with allergies.2


An immune system reaction to a substance that is harmless in most people.1

Allergy shots

A type of allergy treatment that helps the body become less sensitive to an allergen. Also called desensitization or immunotherapy.3


The most severe allergic reaction that can be life-threatening.1


Drugs used to treat allergic reactions, especially respiratory symptoms and itchiness.4


Inflammation of the airways that causes breathing problems. Can be triggered or made worse by allergies.5

Atopic dermatitis

See eczema.


Contact dermatitis

A delayed allergic reaction of the skin. Symptoms include redness, itchiness, blisters, or swelling.1



A substance shed from the body of animals that have fur, hair, or feathers.1


Decongestants reduce nasal congestion by constricting blood vessels in the nasal passages. This makes your head feel stuffy.4


See immunotherapy.

Drug allergy

An allergic reaction to a medicine. Penicillin is a common drug allergy.6

Dust mite

An insect found in homes in bedding, carpet, and soft furniture. A leading cause of hay fever and asthma.1



Inflammation of the skin that causes reddening, itching, swelling, and weeping of skin plaques. People with allergies may have eczema too. Also called atopic dermatitis.7

Elimination diet

A special diet used to narrow the list of foods you may be allergic to.8


Epinephrine is commonly called an Epi-Pen. It is a type of drug that comes in an auto-injector pen. It is used to treat serious allergic reactions.4


Food allergy

An allergic reaction to foods. Peanuts, tree nuts, shellfish, eggs, milk, and wheat are common food allergies.1

Food challenge test

A test in which you are given a suspected food allergen in gradually larger doses under close doctor supervision.8


Hay fever

Sneezing; runny nose; itchiness; inflammation and congestion of the nose, sinuses, and eye. Caused by environmental allergens like pollen, animal dander, mold, or dust mites.1

HEPA filter

High-efficiency particulate air filters screen more allergens from the air circulating in your home or office.9


A substance released by mast cells in an allergic reaction.1


An allergic reaction that causes raised, red, itchy lumps on the skin. Individual lumps are called wheals. The medical term for hives is urticaria.1


Immune system

A group of cells and proteins that protect the body from infections. With allergies, the immune system mistakes allergens as invaders that must be destroyed. This results in an allergic reaction.1


A doctor who specializes in diagnosing and treating conditions of the immune system. An allergist is an immunologist with additional training in allergies.10


Treatments that gradually train the body to be less sensitive to an allergen. Also called desensitization or allergy shots. May also be given by mouth.1


An allergic reaction of tissues that causes redness, swelling, or both.1

Insect allergy

An allergic reaction to insect stings or bites.11



A milky sap produced by rubber trees. Used to make rubber gloves, condoms, rubber bands, and toys.12

Latex allergy

An allergy to natural rubber latex. Most common in people with regular exposure to products made of latex.12

Leukotriene receptor antagonists

Leukotriene receptor antagonists are drugs that work by blocking the action of chemicals in the body called leukotrienes. They treat both allergy and asthma symptoms.4

Lung function test

A test to see how well your lungs are working.13


Mast cells

Specialized cells that live in the body’s tissues. These cells are part of the immune system. They release chemicals that cause allergic reactions when someone is exposed to an allergen.1

Mast cell stabilizers

Mast cell stabilizers (cromolyn sodium) help stop the body from releasing histamines. These drugs treat itchy, watery eyes or itchy, runny nose.4


Tiny fungi whose spores float through the air and grow on damp surfaces. A common allergen.14


Nasal spray

Steroid nasal sprays (corticosteroids) treat allergies by reducing swelling and inflammation.4



A doctor who specializes in treating conditions of the ear, nose, and throat.15


Patch test

A test in which an allergen is placed on the skin and covered with a bandage. Your doctor examines the skin 2 to 4 days later and looks for signs of an allergic reaction.13

Pet allergy

An allergic reaction caused by exposure to cats, dogs, and other animals. The reaction may be caused by proteins found in their dander, skin, saliva, and urine.16


Tiny particles that plants use for reproduction. One of the leading causes of hay fever.1


Scratch test

A test in which a tiny amount of an allergen is scratched into the skin to see if there is a reaction. Also called a skin prick test.1


The process in which the immune system sees a substance as a threat and causes certain cells to create an release antibodies to attack that substance.17

Sinus infection

Inflammation and infection of the sinuses.1


Air cavities connected to the nose.1


A group of drugs used to prevent or suppress inflammation caused by an allergic reaction. Often given as a nasal spray for allergies. Also called corticosteroids.1



A raised, whitish, itchy lump on the skin. Appears after a scratch test if someone is allergic to a substance. This is also the name for individual lumps in hives.1

By providing your email address, you are agreeing to our Privacy Policy and Terms of Use.