Allergy Glossary

This glossary is a comprehensive breakdown of common allergies that will help you to understand common allergy terms better, thus enabling you to have productive conversations with your doctor about your allergy symptoms.

A

Allergen

A foreign substance which your body perceives to be harmful; can trigger an allergic reaction.

Allergic Rhinitis

Allergic rhinitis is a type of inflammation that occurs when the immune system overreacts to allergens such as dust mites, mold, pet dander and pollen. Common symptoms include sneezing, a runny nose, itchy or watery eyes, and an itching of the nose or throat.

Allergy

An allergy is the exaggerated response of the immune system to a foreign substance that is generally safe and poses no threat to the human body.

Anaphylaxis

A severe, life-threatening allergy response which can be characterised by symptoms such as low blood pressure, wheezing, vomiting or diarrhea, swelling and hives.

Angioedema

A type of swelling that is similar to urticaria (hives), but occurs beneath the skin, and not on the surface of the skin. Angioedema is characterised by a deep swelling that commonly occurs around the eyes and lips, and sometimes on the hands and feet.

Antibodies

A specialised protein that is part of the immune system. It is produced by white blood cells, and circulates in the blood. Antibodies seek and attach to foreign proteins, microorganisms or toxins in order to neutralise them.

Antigen

A foreign substance, usually a protein, which triggers an immune system response in the body.

Antihistamine

A type of medication that is used to alleviate allergy symptoms by blocking histamine receptors.

C

Conjunctivitis

Conjunctivitis is an inflammation of the conjunctiva, the tissue that lines the inside of the eyelid. If it is caused by a bacterial infection, it is called "pink eye" or bacterial conjunctivitis. If it is caused by an allergy, it is called allergic conjunctivitis.

D

Dander (Animal)

Dead skin cells which are trapped on animal fur. Pet danders float in the air, settle on surfaces and can accumulate together with household dust. Cat dander is a common cause of pet-related allergies.

Decongestant

A type of medication that shrinks swollen nasal tissues to relieve the symptoms of nasal swelling, such as nasal congestion and mucus secretion.

Dermatitis

An inflammation of the skin that occurs as a result of direct contact with an irritating substance, or an allergic reaction. Symptoms include redness, itchiness, and in severe cases, blistering.

Dust Mites

A common trigger of indoor allergies. These microscopic mites live in the fibres of pillows, mattresses, blankets and carpets, and survive off of our dead skin cells. The inhalation of dust mite droppings can cause allergic reactions which include a runny nose, sneezing and nasal congestion.

H

Hay Fever

See Seasonal Allergies

HEPA

Stands for High Efficiency Particulate Air (HEPA), a filter that forces air through a fine mesh that is made up of microscopic pores which trap harmful particles.

Histamine

An inflammatory mediator that is released by the immune system after being exposed to an allergen. When an allergen enters your body, mast cells that are located in the nose and sinus membranes release histamine. Histamine then attaches to receptors on nearby blood vessels, causing them to dilate. In addition to that, histamine also binds to other receptors located in the nasal tissues, causing allergy symptoms which include swelling, as well as an itchy and runny nose.

Hives

Hives (also known as urticaria) are swollen, red bumps or welts on the skin that are itchy, and can appear as a result of the body’s reaction to certain allergens. These bumps or welts can appear anywhere on the body, including the face, lips, tongue, throat or ears.

Hypoallergenic

A product that is unlikely to cause an allergic reaction.

I

Immune System

The body’s defense system against infections and foreign substances.

Indoor Allergies

Can be characterised by an exaggerated response of the immune system to allergens (see Allergens) commonly that are commonly found indoors, such as mold spores, pet dander, cockroaches or dust mites (also known as perennial allergies). The symptoms of an indoor allergy tends to last longer than the symptoms of an outdoor or seasonal allergy.

M

Mold

A parasitic, microscopic fungi which floats in the air like pollen. Mold spores are a common trigger for allergies, and grows well in damp areas of the home, such as a basement or bathroom. It can also thrive in an outdoor environment, such as damp grass, leaf piles, hay, mulch, or under mushrooms.

Mold Count

A measure of outdoor mold spores in the air. The count is reported as grains of mold spores per cubic meter of air and is defined according to its corresponding level (absent, low, moderate, high or very high).

O

Outdoor Allergies

Can be characterised by an exaggerated response of the immune system to allergens (see Allergens) that are commonly found outdoors, such as trees, grass or weed pollens, and mold spores, amongst others (also known as hay fever or seasonal allergies). The symptoms of an outdoor allergy tends to last longer than the symptoms of an indoor allergy.

P

Perennial Allergies

Also known as indoor allergies, it is characterised by an exaggerated response of the immune system to allergens (see Allergens) that are commonly found indoors, such as mold spores, pet dander, cockroaches or dust mites.

pet dander

Dander (Animal) Tiny scales that shed from animal skin and get trapped on animal fur or hair. Dander float in the air, settle on surfaces and can make up much household dust. Cat dander is a common cause of allergic reactions.

Pollen

A fine, powdery substance (typically yellow in colour) consisting of microscopic grains that are discharged from the male part of a flower (also known as stamens), or from the male cone of a tree.

Pollen counts

A measure of the amount of pollen in the air. The counts are usually reported for three individual pollen types - grasses, trees and weeds. The count is reported as grains per cubic meter of air and is is defined according to its corresponding level (absent, low, moderate, high or very high).

S

Seasonal Allergies

Also known as outdoor allergies, it is characterised by an exaggerated response of the immune system to allergens (see Allergens) that are commonly found outdoors, such as trees, grass or weed pollens, or mold spores.

Sinusitis

An iInflammation of the sinuses that is caused by a bacterial, viral or fungal infection, or an allergy.

U

Urticaria

Also known as hives, urticaria are swollen, red bumps or welts on the skin that are itchy, and can appear as a result of the body’s reaction to certain allergens. These bumps or welts can appear anywhere on the body, including the face, lips, tongue, throat or ears.