What Are Allergies And How Are They Caused?


Allergies are a range of conditions that occur when the body reacts to substances in the environment, known as allergens, that are usually harmless to most individuals. 

Many Australians are affected by allergies at some point in their lives. Common allergens include pollen, dust mites, animal hair, mould, certain foods and insect stings. The reactions can vary from mild irritation to life threatening anaphylaxis.

What happens in the body

An allergic reaction occurs when the immune system overreacts to an allergen by producing antibodies to fight it, even though it is not harmful. In the body’s defence against the substance, it creates a chemical called histamine. While this chemical is usually helpful in protecting the body from disease and infection, when it fights a harmless substance like an allergen, it only causes discomfort and potential danger—the symptoms of allergies.


Allergic reactions have common symptoms that can affect your sinuses and airways, eyes, skin and digestive system. Such as:

  • Red eyes
  • Sneezing
  • Runny nose
  • Scratchy throat
  • Asthma exacerbation
  • Shortness of breath
  • Itchy rash
  • Eczema 
  • Hives
  • Swelling
  • Colic
  • Stomach upset
  • Anaphylaxis 

These symptoms can range in severity depending on the person, and how their body reacts to the allergen. Some people can react strongly to some allergens and not at all to others.


The causes of allergies are difficult to pinpoint, but are mostly due to genetics, changes in the immune system and exposure to new allergens in the environment. 

Anyone can develop an allergy. However, most allergies are inherited. If a parent experiences allergies to a particular substance, there is a high chance their children will too, with symptoms present during infancy or toddler years. Most of these allergies will be lifelong, although some can resolve on their own.

New allergens
While the majority of allergies are identified in childhood, others can develop later in adulthood—seemingly out of nowhere. In some cases, the adult has had the allergy all along, but is only coming into contact with the allergen for the first time. 

Adult-onset allergies can also occur with little explanation. A person may be fine with a substance one day, and not the next. 

Some studies suggest that avoiding common allergens early in life can make individuals more susceptible to allergy later on, because the immune system has not been able to identify the substances in their formative years.


While there are no cures for allergies, they can be effectively controlled and treated. Common treatments include:

  • Avoiding triggering allergens
  • Medications like antihistamines
  • Immunotherapy
  • Emergency epinephrine (EpiPen)

If you are currently experiencing a severe allergic reaction, call emergency now. If you’re experiencing the irritating symptoms of an allergy, contact your GP or find an allergist with Gamma Allergy. They can help you identify allergy triggers and point you toward a suitable treatment.