Allergies and the house dust mite

This leaflet is aimed at people with allergic symptoms, such as asthma or rhinitis. The house-dust mite allergen is one of the most common triggers for these conditions. Here is some advice on how to reduce your exposure to the house dust mite at home.

The house-dust mite is a microscopic creature that lives in soft furnishings in the house. It thrives in warm, humid conditions. Its diet consists of scales shed from human skin. It is the waste products of these mites that allergic people react to. Evidence has shown that although it is impossible to totally eradicate this mite, taking measures which decrease their numbers and clear your environment of their waste products, can reduce allergic symptoms.

Trying to accomplish all the measures outlined in this advice sheet may seem like a daunting and expensive task. But don't let this put you off. You do not need to do them all at once, and there are a few things that are the most important. In general, you should concentrate on reducing general humidity throughout the house, and reducing the amount of dust around. The bedroom is the best place to target initially, as people spent one-third of their time there.


The single most effective measure is to cover the mattress, pillows, and duvet with covers that are impermeable to dust mite allergens. The mattress needs to be covered completely, top and bottom. These special covers are known as micro-porous membrane covers. They provide a barrier to the mite, their droppings and your skin scales, but allow moisture through to prevent discomfort. People on income support may be able to get a budgeting loan from the DSS Social Fund to buy a mattress cover.

All your other bedding should be washed in hot water, 60 degrees centigrade, but check the labels first, as this may damage some materials.

During the day reduce humidity in the bed, allowing it "air", by moving the duvet to the end of the bed.

Keep soft toys for children to a minimum. Put them in the freezer for 6 hours once a month. Then wash them to remove the remaining allergen.

High filtration vacuum cleaners can be used on mattresses.

Ideally carpets should be replaced with sealed wooden or vinyl flooring. Curtains should be hot washed regularly or replaced with blinds that can be wet-wiped clean.

Rest of the house:

Intensive vacuum cleaning with high filtration cleaners reduces the amount of allergens. Older vacuum cleaners should be avoided. You should get a cleaner that is recommended by the allergy foundation.

Vacuum carpets, mattresses, soft chairs, and curtains.

Prevent the build-up of dust. It is best to dust with a damp cloth, as dry dusting puts a lot of dust back into the air. It also makes sense to reduce the number of areas on which dust can build up. Where possible, keep ornaments in display cabinets, and put clothes and other objects in cupboards or drawers.

Try to reduce humidity in the house in general. Mites grow best at 75-80% relative humidity, and cannot live at less than 50% humidity. Humidity gauges are cheap, and you can monitor the levels in your house. The target should be 10-50%.

To reduce humidity you need to leave windows open when showering/ bathing, or use an extractor fan. . Avoid leaving clothes to dry indoors. Ensure good ventilation in the house, so that the air is changed frequently. Dehumidifiers can be useful, but also can be expensive.

Other treatments of furnishings:

It has been suggested by some that ascaricides, liquid nitrogen and air ionisation may reduce allergen load. However, there is little evidence to show that these measures add any significant benefit to the combined system of humidity reduction and allergen removal/containment.

See the British Allergy Foundation Web site ( for current thoughts about the use of ascaricides/ antigen denaturing compounds.

Pet allergens:

Cats in particular are potent triggers for people with allergic tendencies. The best way to reduce allergens associated with pets is to decide not to have them, but you should be aware that improvement in symptoms might take 6-12months. Otherwise the pet should be kept out of bedrooms, and outdoors as much as possible.

seful addresses:

National Asthma Campaign Organisation giving help and advice to asthmatics Address- Providence House, Providence Place, London N1 ONT Telephone 0171 226 2260

Action Against Allergy Registered charity providing information to those suffering various forms of allergy and to those caring for them. Address- PO Box 278 Twickenham, Middlesex TW1 4QQ Telephone 0181 892 2711

British Allergy Foundation Address- Deepdene House, 30 Bellegrove Road, Welling, Kent DA16 3PY Telephone 0181 303 8525

Further information

British Allergy Foundation

National Asthma Campaign

This article published on
25 July 2005

Next review date 7/1/2013



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