Allergies are becoming increasingly common in Australia. According to the Australian Society of Clinical Immunology and Allergy (ASCIA), one in three people will suffer from an allergy at one point in their life.
When you think of allergies you might picture some one who has red, watery eyes, a runny nose and is constantly sneezing. This represents a classical picture of hay fever; however, allergies can take on many forms and cause different symptoms, including itchy skin, hives, welts, swelling and lung problems
How do allergies come about?
Allergies occur when the immune system reacts to something in the environment, causing damage to tissue as it tries to fight off the threat, which should otherwise be harmless to the body. The substances that cause allergies are known as allergens and are varied, including substances such as animal dander, grasses, pollen, dust mites, food, moulds, insects and some medicines.
What happens in the body during an allergic attack?
In acute allergies we must be ‘sensitised’ to an allergen before an allergic response occurs. When we initially come into contact with an allergen no reaction occurs, only sensitisation. However when exposed to the allergen again the body has already been sensitised, and a reaction occurs; the body releases a host of inflammatory chemicals including histamine. The inflammatory chemicals cause typical symptoms seen in allergy which include runny nose (allergic rhinitis), runny eyes, hives and red, itchy skin.
Most allergies are mild to moderate, causing irritation and perhaps a loss of function, however some particular allergies can be life threatening, causing what is known as anaphylactic shock.
Types of allergies
Seasonal allergies – usually occur at varying times of the year generally either autumn/winter or spring/summer. These are as a result of airborne allergens such as pollens or grasses. These can cause runny nose, itchy throat, and red runny eyes.
Perennial allergies – these are allergies that occur all year round. These are generally in response to dust mites, animal dander, mould and occasionally food additives.
* Both seasonal and perennial allergies can be commonly referred to as ‘hay fever’
Animal allergies – an allergy to mainly pet hair. Allergens can arise from the fur, dander, saliva, faeces and urine. Allergic reaction usually occurs via inhalation of the allergen.
Allergic contact dermatitis – this allergy affects the skin and causes a weeping red rash, which usually shows up within 1-2 days of exposure to an allergen.
Hives (urticaria) – causes weal like swellings in the skin which can be as a result of contact with an allergen or ingestion of a food allergen.
Eczema/asthma – allergies can be found in those suffering from atopic conditions such as asthma or eczema. Allergies can trigger a flare up or an attack or can be implicated in causing inflammation.
Atopic individuals have an inherited tendency to allergies. Atopic individuals do not need the initial ‘sensitisation’ exposure to an allergen before responding to it. These people will respond immediately to the allergen even in small amounts. Many cases of eczema and asthma can be linked to atopic individuals.
References available on request