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What causes hay fever?

Despite its name, hay fever isn't caused by hay and it doesn’t cause a fever!

The most common hay fever causes and triggers are discussed below; however, it’s important to note that it’s not caused by a food allergy.

House dust

House dust contains numerous organic and inorganic compounds such as house dust mites, hair, smoke, dirt, fibres, mould spores, pollen grains, insects, mammalian dander (small scales from the skin or hair of pets), as well as secreta (such as saliva) and excreta (such as faeces) from insects, mites and pets.

Of all of these compounds, house dust mites are the most widespread and are commonly found in mattresses, bed bases, pillows, carpets and upholstered furniture. Although they are present all year round, their numbers usually peak during humid periods.


Household pets, especially cats and dogs, are an important source of domestic allergens which are found in the animal’s fur and in house dust. The allergens can remain airborne for long periods of time, and people who are ‘allergic’ to these animals may also react to allergens from other animals such as horses, rabbits and guinea pigs.


Pollens are produced by trees, grasses, flowers and other plants to fertilise the female flower in order to reproduce that plant species. The type and number of pollens vary according to an area’s vegetation, geography, temperature and climate.

Pollens from insect-pollinated plants (such as the Australian wattle) are too heavy to remain in the air and therefore pose little risk. The most troublesome pollens tend to be airborne such as those produced by Northern Hemisphere species of grasses, trees and flowering weed species. However, the main pollen for Queensland, Northern Territory and northern Western Australia is Bahia grass or paspalum which is a southern African grass.

Fungal allergens

Fungi, such as mould, reproduce by spores and can release large amounts of allergenic spores into the indoor and outdoor environments. Outdoor moulds can be present in all conditions, with seasonal peaks in hot and humid conditions, while indoor moulds are associated with dampness. They are particularly plentiful in bathrooms and kitchens.

Occupational exposures

Occupational irritants can cause and worsen the symptoms of hay fever. They include different forms such as fumes, dust, vapours and gases, or different types such as chlorine or wood dust.

Common allergens in the workplace can include natural latex rubber (made using a water-soluble protein obtained from a particular rubber tree), bakery allergens such as wheat, enzymes and mites that may be in stored cereal, while people working in fish/seafood processing plants can become sensitised from breathing fish/crustacean proteins in. Scientists in cleaning product companies can also sensitise to the enzymes contained in products such as washing powder, while laboratory workers can sensitise to rats and mice.

The correct drugs and treatments can be effective in reducing your symptoms. You should seek advice from your doctor or a pharmacist about which medicines or treatments will relieve your particular symptoms based on their severity.

Not sure what to do next?

If you are still concerned about your hay fever, check your symptoms with healthdirect’s online Symptom Checker to get advice on when to seek medical attention.

The Symptom Checker guides you to the next appropriate healthcare steps, whether it’s self care, talking to a health professional, going to a hospital or calling triple zero (000).

Last reviewed: July 2015

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If you have a respiratory condition such as asthma or hay fever, make sure you are well prepared when the summer temperatures hit their peak.

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