What Are Allergies? And Why Do We Get Them?

There are many different types of allergies and they all have different symptoms, so what are they?

An increasing number of Australian’s have some type of allergy, with one in five people suffering from an allergy at some point in their lives.

Allergies can vary from a mild annoyance to a life-threatening condition, therefore, it’s important to know what an allergy is and how to find out if you have one.

The Facts

Allergies are conditions caused by hypersensitivity reactions in the body’s immune system after it’s exposed to a harmless substance in the environment. The immune system has an overreaction to the substance and gives you allergic symptoms.

According to the experts at House Call Doctor, these reactions can vary from mild to life threatening and can be immediate or delayed.

There are a wide variety of allergic diseases. Some of these diseases include hay fever, food allergies, dermatitis, allergic asthma, and anaphylaxis.

Common triggers

The substances that can trigger an allergic reaction are called allergens.

The most common allergens in Australia are:

  • Dust mites
  • Pollen
  • Food
  • Pets and pet hair
  • Insect stings or bites
  • Moulds
  • Medicine.


The type of symptoms you experience depends on both the type of allergy you have and you as an individual, however, there are some symptoms that are common across different allergies.

Allergy symptoms can include:

  • Runny nose, stuffy nose and sneezing
  • Wheezing or shortness of breath
  • Cough
  • Rash, hives or eczema
  • Fatigue
  • Headache
  • Nausea and vomiting
  • Fever.


Correct diagnosis of an allergy is important so that a person can avoid the allergen and decrease their chance having an allergic reaction. Allergy testing is the most effective way find out if you have any allergies, the most common tests are:

  • Skin prick testing is used to find immediate allergies. It involves making small punctures in the skin and then applying small amounts of allergens or allergen extracts. After 30 minutes, if a patient is allergic to a substance a visibly red inflammatory reaction will be present. This response can vary from the slight reddening of the skin up to a full-blown hive if you have high sensitivity.
  • Patch testing is used to test for delayed skin-contact reactions to allergens, such as allergic contact dermatitis. Adhesive patches that have been treated with allergens are applied to a patient’s back. The skin is then examined for allergic reactions 48 hours and two-three days after they have been applied.

Management and Treatment

There are a number of options for allergy treatment.

  • Allergen avoidance relies on identifying the cause of the allergy. Once the cause has been found, steps can be taken to limit exposure.
  • Medications can also be used to treat allergies and symptoms. Some of these medications include antihistamines, nasal sprays, eye drops, and adrenaline.
  • Allergen immunotherapy or desensitisation is available as a long-term treatment. It aims to change the immune system’s response to the allergen and involves regular, increasing exposure to allergen extracts via tablets, sprays, drops, or injections.

If you think you might have an allergy, please contact your doctor.

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