WHAT EXACTLY ARE ALLERGIES?
We’ve all heard the term “allergies.” It’s common knowledge that people can be allergic to a range of things: pollen, dust mites, moulds, pet dander…the list goes on. But what is the definition of an allergy? What happens inside our bodies to cause allergy symptoms? What are common allergy symptoms? Are there different allergy seasons in Australia?
OUR IMMUNE SYSTEM AT WORK
Our immune system is designed to protect us from harmful invaders called “pathogens” such as viruses, bacteria, and fungi. To help protect against these invaders, our immune system produces highly specialised proteins called “antibodies”. The antibodies recognise harmful invaders by attaching to them and signal the immune system to send substances to destroy them.
An allergic reaction occurs when the immune system overreacts to a normally harmless substance, such as grass, pollen, pet dander or dust mites—known as an allergen. Your immune system reacts by producing antibodies. This is called “sensitisation.” The next time your immune system encounters the pollen/pet dander/dust mites, the antibodies recognise it and tag it as an invader. The antibodies travel to certain cells that release chemicals, called histamines, causing allergy symptoms often found in the nose, eyes, and skin. The result? Allergy symptoms.
WHAT ARE HISTAMINES AND WHAT DO THEY DO?
Histamines are always present in the body in small amounts but more get released when an allergen is present. The histamine reaction serves two main functions:
- It causes “vasodilation” which is when the walls that surround blood vessels are relaxed, causing the interior of the blood vessel to widen.
- It causes fluid to be released. The widening of the blood vessels allows white blood cells (infection fighters) to move easily to the site of the infection and fluid secretion helps the body get rid of the allergens. However, this release of fluids and vasodilation is what causes some of the more common allergy symptoms.
COMMON ALLERGENS
Allergies can be year-round or seasonal. Seasonal allergies commonly known as hayfever, tend to be due to allergic reaction to pollen, resulting in runny and itchy nose, eyes and palate.
Year-round allergies can be caused by many allergens, most commonly dust mites, pet hair (dander) and moulds.
WHEN IS ALLERGY SEASON IN AUSTRALIA?
Spring (September - November): Pollens of grasses, trees and weeds; mould.
Summer (December - February): Pollens of grasses, trees and weeds; mould.
Autumn (March - May): dust mites, pet dander and mould.
Winter (June - August): dust mites, pet dander and mould.
COMMON ALLERGY TERMS
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Allergen |
The substance that triggers an allergic response. Common allergens include dust, pollen, animal dander from cats and dogs, mould. |
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Allergy |
A chronic condition involving an abnormal reaction to an ordinarily harmless substance called an allergen. |
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Allergy symptoms |
Occur when the body overreacts when exposed to a foreign substance which are mostly harmless in other people, for example, sneezing, runny nose, watery/itchy eyes. |
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Antibodies |
Highly specialised proteins the body produces to recognise harmful invaders by attaching to them and signalling them to send substances to destroy them. |
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Antihistamine |
Describes medication or medicine used to reduce histamine – the major cause of allergy symptoms – and its effects on the body. AERIUS is a non-drowsy 24 hour antihistamine. |
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Dander |
Tiny particles of skin, saliva and sweat shed by animals with fur or feathers. The particles contain a protein that can cause reactions in people who are specifically allergic to these triggers. Very light, it can remain airborne for hours after the animal has departed and may be carried to other destinations by pet owners. |
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Dust mites |
A common cause of perennial (year-round) allergic rhinitis. |
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Hayfever |
Also known as seasonal allergic rhinitis, hayfever is an allergic reaction to pollen from grasses and trees. |
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Histamine |
A naturally occurring chemical that causes many of the common allergy symptoms. |
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Hives |
Raised, red, itchy bumps on the skin, which are the result of an allergic reaction. |
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Immune Cascade |
The stages of an allergic reaction starting when an allergen enters the body, triggering immune system mast cells to release histamine. This can ultimately result in an allergy attack of sneezing, itching and irritation. |
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Immune system |
The body’s protection from outside invaders such as viruses, bacteria, fungi. |
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Mould |
A common allergen found in wet, damp places aiding in the breakdown of materials. |
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Perennial Allergic Rhinitis |
Year-round allergies affecting the sinus and airways which can be caused by many allergens, most commonly dust mites, pet hair (dander) and moulds. |
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Pollen |
Air-borne plant matter, which is the major cause of hayfever – particularly in hot, dry and windy weather. |
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Seasonal Rhinitis |
Commonly known as hayfever, this describes an allergic reaction to pollen, resulting in runny and itchy nose, eyes and palate. |
| Sensitisation |
The body's first reaction to foreign substances with the production of antibodies. |
