House Dust Mites

House dust mites are small organisms that are invisible to the naked eye. Mites live by eating skin scales shed by the human body and prefer warm, dark humid conditions. They are harmless except to people who are allergic to them. The substances that cause the allergy are present in the mite faecal pellets. Mites are the most common cause of year-round allergic asthma and rhinitis, and may also play a role in eczema.

Where do mites live?

The biggest exposure to mites in the home is usually in the bedroom, particularly from mattresses that offer the mites warmth, humidity and foods for their growth. They also live in pillows, blankets, duvets, carpets, curtains and soft furniture. As well as the bedroom there are often quite high numbers of mites in the living area.


How Can Dust Mites be Controlled?

  • The best treatment for allergy is to avoid the cause

  • It is impossible to get rid of all mites but it is possible to reduce their numbers and to reduce exposure to them.

  • Special barrier covers for your bedding (mattress, duvet and pillows) are helpful in reducing your exposure to house dust mite. These have not been proven to be effective on their own and therefore they should be used in conjunction with cleaning and other measures

  • Vigorous cleaning has been recommended to reduce house dust mite numbers, but even very regular cleaning may not reduce mite numbers sufficiently to reduce symptoms. Therefore cleaning should always be carried out in conjunction with using the special barrier covers on bedding

  • High humidity encourages mite growth so reducing the moisture level in the house is helpful to open windows or vents in kitchens and bathrooms. To stop damp spreading to the rest of the house, keep the door to these rooms closed.

  • Avoid drying clothes indoors - especially in bedrooms and living rooms. If you have to, open the window and close the door. Tumble dryers should be vented to the outside if possible. Opening windows in the bedrooms helps to reduce humidity.


Avoidance Measures

  • If possible buy a new mattress and enclose it immediately in a special barrier cover.

  • If using an old mattress, ensure that it is thoroughly aired and vacuum cleaned. Then cover with a specialist barrier cover.

  • All beds in the sufferers bedroom should be covered,

  • Duvets should also be covered if they cannot be washed regularly and air the beds before remaking. 

  • Leave special covers in place and wipe down to prevent build-up of allergen 

  • If possible replace blankets with synthetic filled duvet

  • Use sheets, duvets, pillows or blankets that can be washed regularly. Wash at 55°C or above to kill mites. Washing at lower temperatures removes the allergen, but does not kill mites. 

  • Avoid feathers, kapok, wool eiderdowns, candlewick bedspreads - dense fabrics encourage mite infestation. 

  • Buy cheap, synthetic pillows and replace them every six months.

  • "Non-allergenic" pillows means that you should not have a reaction to the filling. The dust mites populate these pillows just as much as others so wash regularly or use special covers.

  • When using bunk beds, allergy sufferers should always sleep on the top bunk

  • Soft toys should be washed regularly. Alternatively, once a month they can be placed in a plastic bag in the freezer overnight and then vacuumed.

  • Ideally keep animals out of the house: they should always stay out of the bedroom.



  • Vacuum thoroughly and regularly. Once a week - more often may stir up dust.

  • Ideally use a vacuum cleaner with a micro-filter that retains the dust mites and their particulate.

  • Steam vacuum cleaners can be of much value in removing allergen particles from carpets and upholstery, but it is important that as much water as possible is recovered, as high humidity, resulting from dampness, encourages mite growth.


General Advice

  • Vinyl or wood floors are better than carpet.

  • Short pile, man-made carpets should allow less allergen to become airborne than a longer pile carpet.

  • Do not brush or shake rugs indoors.

  • Use a damp cloth when dusting - including soft furnishings.

  • If you are very sensitive get someone else to do the cleaning or alternatively wear a mask.

  • Cut down on dust gathering objects - keep ornaments in a display cabinet, books in a closed cupboard.

  • Lightweight curtains should be washed regularly. Roller or vertical blinds make a good alternative. When you buy new furniture, consider cane or leather/leather -like furniture which is easy to clean, or loose covers which can be washed regularly.


Product information


Ideally you will need covers that have the following qualities:

  • Totally encloses the mattress, pillow and duvet

  • Total barrier to house dust mite and its allergen

  • Moisture permeable to prevent excess heat and sweating

  • Wipe down top surfaces

Plastic covers can be effective but will not provide moisture permeability. People with eczema should note that excessive heat could make their condition worse.


Avoiding Indoor Allergens

What are allergens?

Allergens are substances that trigger the immune system to promote an allergic reaction.


What is an allergic reaction?

An allergic reaction occurs when the immune system reacts to a normally harmless substance by making a specific antibody to fight it. Each time the person encounters the offending allergen, it links up with the antibody to cause the release of histamine and other chemicals into the tissues. These substances cause the irritation and inflammation of allergic disease.

Allergies occur most commonly in people with a family history of allergic disease, although this is not always the case


What are the symptoms caused by indoor allergens?

Indoor allergens most commonly affect the nose, chest, skin and eyes.

  • Itchy, runny or congested nose, sneezing.

  • Irritable airways, coughing, tight chest, wheezing, shortness of breath.

  • Itching, watering, inflammation of both eyes.

  • Itchy skin, rashes, wheals.

  • Congested sinuses and headache.

  • Disturbed sleep.

  • Poor concentration.

  • Symptoms worse indoors, in bed or early morning

Unlike hay fever, symptoms can occur throughout the year although symptom severity may vary from day to day and is normally worse in winter. You may improve abroad in a hot or very cold but dry place.


What are the main causes of indoor allergies?

House Dust Mites

House dust mites are present in all houses in the UK and are the most prevalent of all allergens, causing allergic reactions in 85% of asthmatic children. The warmth and humidity in modern UK homes is an ideal breeding environment for them. They cannot survive in extremely dry or cold conditions. Like most living creatures, they require warmth, food and water and, as they cannot drink, they need to absorb moisture through their skin. Our beds provide the ideal environment, with a supply of our shed skin cells (their food source), water from our sweat, expired breath, and warmth. They also find skin cells and other proteins to eat in carpets, upholstered furniture, fabrics and furry toys. The allergen which triggers the immune system is mainly in the mite droppings, which are very dry and fragment into fine particles. These become airborne and are easily inhaled deep into our airways and lungs. The particles settle quickly into the depths of our pillows, mattresses, duvets, upholstery and carpets.


Animal Allergens

Animal allergens are the next most frequent cause of allergic reactions. The allergen that triggers allergic responses to animals is found in their saliva, skin and urine. When the animal grooms, the allergen coats the skin, fur or feathers, and is spread by shed skin cells (dander) as well as by licking. The particle size of the allergen is extremely small and therefore easily airborne and breathed in, causing respiratory symptoms, itchy eyes, sneezing and skin irritation. Cat allergen, particularly, may be found on walls and ceilings many months, or even years, after the animal has left the house. It can also be found on the clothes and shoe soles of people with a cat, so it is easily spread. Feathers are rarely a cause of allergy although the dust in feather pillows can be a cause of symptoms, as can the mites that grow in them.

Smaller domestic animals, such as guinea pigs and hamsters distribute allergen in the urine in the bedding. This allergen easily becomes airborne when the animal scurries around in its cage. It is not advisable to keep these pets in the bedrooms of allergic people. Parrots and other birds are another common cause of allergic reactions to their feathers. Any animals, insect or creature can be a cause of allergic reactions. Even fish are not always the solution, as there are many allergenic proteins in fish food granules, and moulds can flourish in the damp environment.


Mould Spores

Allergy to mould spores is quite common and is often overlooked. Moulds are ubiquitous and present indoors for most of the year. Mould also prefer damp, warmer environments so are particularly found in bathrooms, kitchens, on refrigerator door seals, shower curtains and particularly in houses that have obvious damp patches and black mould on window frames. Due to the high level of humidity, they are also found in our beds. The water reservoirs of dehumidifiers can be a breeding ground for moulds Spores are sometimes hidden underneath wallpaper and commonly present in the soil of houseplants. Houses built in areas of underlying water, and in river valleys, are often damp.

Symptoms from mould allergy may be better in hot, dry weather and become troublesome on damp, cloudy and misty days.


Identifying the Causal Allergen

Allergy sufferers are rarely offered allergen diagnosis or advice. Identifying the causal allergen is an important step in taking control of your allergy, allowing you to reduce exposure to those substances that trigger your symptoms, You should be referred to an Allergy Specialist or GP with a special interest in allergies, for diagnosis. Your levels of specific IgE will be tested by either skin prick or blood testing. This, together with clinical history, symptoms and examination will enable the specialist to correctly diagnose your condition and plan your future management Skin prick testing is a painless procedure in which one drop of each allergen is placed on the skin (usually on the lower inner arm), pricked with a specially designed lancet and blotted. If you are allergic to that substance, a small wheel of approximately 3-6mm, surrounded by an inflamed area, will appear within 15 minutes. This will Itch for a short time before fading.


Controlling Indoor Allergens

Housedust mite allergens

Most efforts at controlling dust mites should be aimed at areas of the home where you spend most of your time and where dust mite load is greatest, i.e. bedrooms and living areas

  • Use allergen-proof barrier covers on all mattresses, duvets and pillows. These should be breathable and should completely enclose the item. Buy products that have been tested to make sure that they prevent the escape of house dust mite allergen.

  • Wash all bedding that is not encased in barrier cover (e.g. sheets, blankets) every week Washing at 60 degrees or above will kill mites. Housedust mite allergen dissolves in water so washing at lower temperatures will wash the allergen away temporarily, but the mites will survive and produce more allergen after a while

  • If possible remove ali carpeting in the bedroom. Vacuum hard floors regularly with a high-filtration vacuum cleaner (see below).

  • Remove all carpeting from concrete floors. Such floors trap moisture allowing dust mites and mould spores to thrive Seal the floor with a vapour barrier, and then cover it with a washable surface such as vinyl or linoleum

  • Where carpets cannot be removed, vacuum regularly with a high-filtration vacuum cleaner Use a high-temperature steam-cleaner to kill mites effectively. Products are available that can be sprayed on carpets to kill mites; these are effective but should be used with care if you suffer from respiratory symptoms, and should not be used in areas where children play on the carpet, or on soft toys or pillows.

  • Use a high-filtration vacuum cleaner with filters capable of retaining a high proportion of the smallest particles (HEPA filter, S-class filter or similar). Details of suitable vacuum cleaners are available from Allergy UK.

  • Damp-wipe all surfaces each week (pelnet tops, window sills, tops of cupboards and so forth).

  • Use light washable cotton curtains, and wash them frequently. Reduce unnecessary soft furnishings.

  • Vacuum all surfaces of upholstered furniture at least twice a week.

  • Washable stuffed toys should be washed as frequently and at the same temperature as bedding, alternatively, If the toy cannot be washed at 60 degrees place it in a plastic bag in the freezer for at least 12 hours once a month and then wash at the recommended temperature

  • Reduce humidity by increasing ventilation. Use trickle-vents in double-glazing, or open windows. Use extract fans in bathrooms and kitchens.

  • If necessary use a dehumidifier to keep indoor humidity under 50% (but over 30% )


Animal Allergens

If you have a proven allergy to your pets then the best advice is to remove them from your home. After your pets are removed you should do the following:

  • Vacuum all surfaces to remove pet hair; also wash all walls and floors

  • Steam cleans all carpets and upholstery. Run your heating or air conditioning system to help quickly dry these surfaces and prevent mite or mould growth.

  • Wash all bedding and draperies, even if your pet was not directly in contact with them.


Reducing animal allergens

  • Do not obtain any new pets.

  • Animals should not be allowed in the living area and never in the bedroom.

  • Wash cats and dogs 1-2 times a week.

  • Groom dogs regularly outside.

  • Wash all bedding and soft furnishings on which an animal has layed.

  • Wash everything, including walls, if you have a cat.

  • Allergic children should not play on carpets where animals have been

  • Horse riders should change their clothes before entering the house of allergic people as horse allergen sticks to clothes


Mould Allergens

  • Avoid damp basements, compost piles, fallen leaves, cut grass, barns and wooded areas - or wear a face mask if these places or things are unavoidable.

  • Tackle any damp areas on walls (due to blocked/leaking gutters etc). Pay particular attention to walls behind kitchen units and cupboards, the lack of ventilation often means that excess mould grows in these areas. Tackle condensation.

  • Use a dehumidifier to keep indoor humidity at 50% or less. Empty and clean the reservoir regularly

  • When showering or cooking, keep internal doors closed to prevent damp air spreading through the house. Use extract fans and cooker hoods vented outside.

  • Make sure that your tumble dryer is vented outside during use, or use a condenser- dryer. Try not to dry damp clothing indoors.

  • Do not let food decay and clean and thoroughly dry problem areas such as refrigerator seals,

  • Do not hang clothes in damp cupboards or pack clothes too tightly in wardrobes: Leave wardrobe doors ajar to ventilate the clothes

  • Get rid of old foam pillows and mattresses,

  • Strip wallpaper from damp walls

  • Keep houseplants to a minimum and change the soil regularly

  • Do not use humidifiers.

  • Avoid using paraffin heaters and bottled gas heaters- they generate large amounts of moisture


Other Considerations

  • Allergic people may be likely to develop other allergies over time, so all allergy sufferers should follow these guidelines for allergen reduction

  • Inflammation & symptoms develop over a long time so benefit may not be immediate.

  • Cigarette smoke makes all allergic conditions worse because of the aggravation of already inflamed skin and membranes. Nobody should smoke in the house of an allergy sufferer

  • Early exposure of babies to allergens and smoke is associated with later development of allergic disease.

  • People with sensitive airways and skin should avoid all unnecessary chemicals, such as air fresheners and most commercial cleaning materials (contact Allergy UK for cleaning tips)

  • Diagnosis by alternative methods is not recommended.

  • Allergy test results should be interpreted by an allergy expert in conjunction with clinical history.