House dust mites are one of the most common allergen triggers for asthma, especially in humid and coastal parts of Australia.

These microscopic creatures feed on dander (shed skin scales) that have been decomposed by fungi.

They live in soft furnishings such as beds, bedding, carpets, upholstered furniture, soft toys and clothing, and are mostly found in people’s homes rather than public spaces.

Most of the allergen comes from their faecal pallets, while their body fragments also contribute. Allergen particles range in size from five to 40 microns.

Dust mite allergens do not typically remain airborne for long but dust-raising activities such as vacuuming, dusting, playing on the floor and moving about in bed will stir them up.

What you can do

If you have a proven allergy to house dust mites, you may be advised to take measures to try to reduce your exposure.

This can involve killing house dust mites, removing the allergen they produce and reducing areas where they can live and breed. Multiple strategies will be more effective than just one.

Around the house

• Use a damp or electrostatic cloth to dust hard surfaces, including hard floors
• Vacuum carpets and soft furnishings weekly, using a good quality vacuum cleaner (these will mostly have high efficiency particulate air (HEPA) filters)
• Ask someone else to do the vacuuming while you leave the room, as vacuuming (even with a HEPA filter vacuum) increases the amount of dust mite allergen in the air for up to 20 minutes
• Reduce indoor humidity – see our Indoor Humidity information sheet
• Clean window coverings (blinds and curtains) regularly (venetian blinds or flat blinds are easier to clean than heavy curtains. Washable curtains or external shutters are other options)
• Consider leather or vinyl lounges instead of fabric
• As well as being a source of allergens themselves, pets also contribute to dander on which the mites feed

Try a hot wash

Washing bedding in water hotter than 55°C will kill mites and wash away the allergen they produce.

If you can’t wash in hot water, use a sensitive commercial product formulated to kill dust mites in cold water. Hot tumble drying of washed items for 10 minutes after they are dry will also kill mites.

Dry cleaning is not as effective as it will kill house dust mites but won’t remove the allergen.

In the bedroom

Steps to reduce exposure should focus on your bedroom, as a significant amount of exposure to house dust mites is from your bed.

• Open the curtains and air your bedding in the sunshine
• Wash sheets and pillowcases weekly in water hotter than 55°C
• Cover your mattress, quilt and pillows with mite-resistant cases, and wash these regularly (a full encasement will be better than a cover)
• Use bedding products treated with an anti-microbial product like Ultra-Fresh®, Sanitized® or HealthGuard®.
• Remove untreated underlays
• Remove soft toys from the bedroom, or wash them weekly in water hotter than 55°C
• Freezing soft toys and other small items overnight kills the mites but doesn’t remove the allergen

Other methods

• Pesticides are not recommended as their effectiveness is unclear and their toxicity may present a risk. There are some safer anti-microbial products that may assist in reducing dust mites (even a eucalyptus spray may assist), although don’t expect a miracle.
• Ultraviolet vacuums or cleaning services are promoted as a method of killing house dust mites. Exposing dust mites to ultraviolet light for a sufficient time will kill dust mites but is not likely to be effective while mites are in their natural habitat such as mattresses or carpet because it requires a prolonged exposure and has inherent operational drawbacks.
• An effective air purifier (most likely with a HEPA filter) will likely capture any airborne dust mite matter passing through it, but because the matter is relatively heavy, it tends not to stay airborne long.