Why do allergies happen?

March 1, 2023


Why do allergies happen?

Allergies are very common, with around 1 in 5 people in Australia experiencing an allergy during their lives.

The severity of allergies varies from person to person and can range from minor irritation to anaphylaxis.

When you have allergies, your immune system makes antibodies that identify a particular substance as harmful, even though it isn’t.

These are usually everyday items such as:

  • Peanuts
  • Animal hair
  • Pollen
  • Fish
  • Mould
  • Dust mites
  • Medications

When you come in contact with the substance, your immune system’s reaction can inflame your skin, sinuses, airways or digestive system, typical of an allergic reaction.

When do allergies feel like a cold?

A cold is an infection caused by a virus. Allergies are your immune system’s reaction to a substance like pollen.

Because the two conditions cause similar symptoms, like sniffles and stuffiness, many people get them mixed up.

The only ache you may feel with allergies is a headache from all that congestion.

Allergies can cause sore throat if there’s enough irritation from post-nasal drip and coughing, but if you’re experiencing a sore throat or mild body aches, they’re more likely a sign of a bad cold.

Here’s a breakdown of common symptoms of a cold vs allergy:

Are allergies genetic?

Not exactly. The tendency to develop allergies is often hereditary, which means it can pass down through genes from parents to their kids.

It could be eczema, hayfever or asthma, or all three of these conditions.

But just because a parent has allergies doesn’t mean that their kids definitely get them.

And someone usually doesn’t inherit a particular allergy, just the likelihood of having allergies.

Some kids have allergies even if no family members are allergic.

Experts think other factors come into play, like your environment, air pollution, respiratory infections – even diet and emotions.

How do allergies affect eyes?

The nose, eyes, sinuses and throat are affected by substances that are inhaled.

During an allergic reaction, these areas can become swollen, inflamed or itchy, with extra mucus produced in the nose and fluid in the eyes.

The symptoms of eye allergies can vary greatly in severity and presentation from one person to the next.

Your eyes may become increasingly red and itchy.

Most people will present with at least some degree of irritation or foreign-body sensation and clear, watery discharge.

What happens if I rub my eyes?

Rubbing your eyes may seem like a relatively harmless thing to do.

Most of us do it regularly, whether we’re suffering from hayfever or a common cold, or are just feeling tired and groggy.

Rubbing stimulates tears to flow, lubricating dry eyes and removing dust and other irritants. Rubbing your eyes can also be therapeutic.

Pressing down on your eyeball can stimulate the vagus nerve, which slows down your heart rate, relieving stress.

However, if you rub your eyes too often or too hard, you can cause damage in a number of ways…

  • Rubbing your eyes may cause tiny blood vessels to break, resulting in bloodshot eyes or dark undereye circles.
  • When you rub your eye, germs are easily transferred from your hands, which can result in infections like conjunctivitis. Read more about conjunctivitis.
  • Sometimes people get a foreign body stuck in their eye and the natural instinct is to rub it to try and remove the object. However, rubbing against the object can very easily scratch and damage the cornea.
  • Rubbing is most dangerous in people with certain pre-existing eye conditions. People with progressive myopia (a type of short-sightedness caused by a lengthened eyeball) may find that rubbing worsens their eyesight. Similarly, those with glaucoma may find that the spike in eye pressure caused by rubbing the eyes can disrupt blood flow to the back of the eye and lead to nerve damage and, ultimately, permanent loss of vision.

Studies have shown that continuous eye rubbing in susceptible individuals can also lead to thinning of the cornea, which is weakened and pushes forward to become more conical. We write about various topics that might affect your sight and vision. As certified optometrists in Perth who have been serving for three generations, we care about your health. 

This is known as Keratoconus, and is a serious condition that can lead to distorted vision and possibly the future need for a corneal graft. Read more here

Do your eyes feel itchy or watery sometimes?

​Request an appointment now with Rhiannon Richer or Damon Ezekiel


In addition to owning and managing Ezekiel Eyes, Damon is a contact lens consultant to various research organisations. He regularly lectures and conducts workshops in contact lens practice throughout Australia, Asia and the United States. Damon graduated from the University of NSW with a Bachelor of Optometry in 1989. He is now married with two children and enjoys running, hockey, swimming, piano, travelling and trekking.

Damon’s professional associations include:
President of the International Society of Contact Lens Specialists
Practising Fellow of the Scleral Lens Education Society
Fellow of the Cornea & Contact Lens Society of Australia
Fellow of the American Academy of Optometry
Member of Optometry Australia
Member of the Orthokeratology Society of Australia
Member of Alcon Australia advisory panel