What are dust mites?

Dust mites are mostly found in the house and commonly trigger symptoms in people with asthma, allergic rhinitis (hay fever) or eczema, who are allergic to them. There are ways you can help to reduce the number of dust mites and their allergen (the substance they produce that causes allergy), as well as to control allergic symptoms.

Dust mites belong to the same family as spiders and are so tiny you cannot see them without a microscope. They feed on discarded human skin, house dust, and other microscopic food sources such as pollen and fungal spores.

Dust mites do not bite or sting. However, their bodies contain a strong allergen, and they also shed droppings and skin.

Where are they most commonly found?

Dust mites are mostly found in homes with higher humidity levels and constant warm temperatures, so they are more common in coastal areas of Australia than in inland, dry areas.

In the house, they live in layers of dust that have settled, particularly in high traffic areas. Because they feed on discarded skin cells, they are also commonly found in the bed and bedroom. When you are making your bed, they can become airborne and settle in other areas of the house. They also like to live in soft furnishings such as couches, curtains, and deep carpet.

There tend to be more dust mites during changes in the seasons, when people are often spring-cleaning their houses. This can affect people who are allergic to them.

How can dust mites affect your health?

Many people who have asthma, eczema, allergic rhinitis (hay fever) or other allergies are allergic to dust mites. The allergen created by dust mites can trigger symptoms of their condition.

If you suspect that you are allergic to dust mites, it is important to confirm that dust mites are a trigger for your asthma or allergy. Allergy tests such as a skin prick test or specific blood tests will help to determine this. However, a positive test does not mean that the dust mite will trigger your symptoms. Talking to your doctor and understanding the times and seasons your symptoms are triggered will help you know if dust mites affect your asthma or allergy.

How can you reduce dust mites?

The allergen is present both in the mites as well as in their droppings and discarded skin cases. So it is important to try to reduce all of these. Unfortunately, it is not possible to completely remove dust mites from the house, and you will need to do more than one thing to reduce their numbers and effect.

The best place to start is in the bedroom:

• Wash sheets and pillowcases every week in water hotter than 60 degrees Celsius (60°C). This will kill the dust mites and remove the allergen. If you cannot use hot water, try a commercial washing product containing tea tree or eucalyptus oils, which kills dust mites and can be used in cold water.
• Open the curtains and allow sunshine into your room and, if possible, onto your bed. Dust mites do not like bright light.
• Put dust mite-resistant protective covers on your mattress, doona and pillows. These need to be washed every 8 weeks.
• If you do not have protective covers, wash blankets and doonas every 3 months.
• Remove sheepskin underlays from your bed.
• Remove pillows and soft toys from the bedroom or wash them every week. Soft toys can be put into the freezer to kill the dust mites, but this will not remove the allergen.

For all rooms:

• Replace fabric curtains with venetian blinds or shutters to make them easier to clean. If you cannot do this, wash curtains regularly, if possible.
• Vacuuming will not completely remove all dust mites or allergens because mites burrow deep into thick carpet. However, it will reduce their numbers so it should be done weekly. It is more effective to vacuum dust mites and droppings from hard surface floors. High efficiency particulate air (HEPA) filter vacuum cleaners may remove more allergen than a standard vacuum cleaner. As vacuuming lifts and swirls the mites and allergens around the room, someone else may need to do this and you should avoid entering the room for 20 minutes afterwards.
• Reducing the overall humidity of the house and increasing air circulation may help to keep dust mites at a lower level.
• Use a damp or electrostatic cloth to dust hard surfaces.
• If possible, use vinyl or leather lounges rather than fabric.

What are the symptoms of dust mite allergy?

If you have a diagnosed allergy to dust mites, your symptoms will depend on whether your condition is asthma, eczema, hay fever or another allergic condition. Your doctor will work with you to help manage your symptoms, which may involve asthma or allergy medicine, as well as avoiding the dust mites.

In some cases, your doctor may prescribe immunotherapy, which involves gradually increasing doses of the dust mite allergen to help reduce the severity of symptoms. This can take 3 to 5 years of treatment to be effective.

Further information and help

For more information about dust mite or other allergies, visit the Australasian Society of Clinical Immunology and Allergy (ASCIA) website.

To get help managing your asthma, eczema or allergy symptoms, or to test if dust mites trigger your allergic condition, see your doctor.

Alternatively, call Healthdirect on 1800 022 222 to speak with a registered nurse (known as NURSE-ON-CALL in Victoria).