Q & A

House dust mite allergy typically develops in childhood and does not go away on its own. As children with house dust mite allergy have a greater risk of developing other allergies or asthma, it is therefore important to get the allergy under control.

Some children may find that their symptoms ease during the day or during the summer. This is because they are in a place without house dust mite allergens and are not affected. House dust mites primarily thrive in warm, humid environments, including the bed, and symptoms are therefore worse in the evening, at night and in the morning, as well as during the colder season, when the mites move indoors into our homes and humidity is high.

House dust mite allergy does not go away on its own, but it can be managed. While symptom-relieving allergy medication can keep symptoms under control, allergy immunotherapy can treat the cause of the allergy and provide a long-lasting effect.

Children may experience different symptoms of house dust mite allergy, such as a blocked or runny nose, coughing, sneezing, breathing problems, itchy and watery eyes and worsening of childhood eczema (atopic dermatitis).

Symptoms of house dust mite allergy can closely resemble a cold, but unlike viral infections, the symptoms do not go away.

The discomfort will typically be most pronounced at night or in the morning, which means that children with house dust mite allergy may feel tired and unwell as a result of a poor night’s sleep.

House dust mite allergy is sometimes referred to as an allergy. However, this term is misleading, as it is not the dust itself that causes the allergy, but rather house dust mites.

House dust mites live in textiles, especially around the bed environment, where they reproduce very quickly and leave behind body parts and excrement that contain the substances that people with house dust mite allergy react to.

Be aware that children with sensitive mucous membranes may react to dust even if they are not allergic to house dust mites.

If your child has cold symptoms such as a blocked nose, runny nose, sneezing and coughing – which do not disappear after a week or two – these may be signs of house dust mite allergy. Unlike seasonal or situational allergies such as pollen allergy and pet allergy, house dust mite allergy causes symptoms all year round.

Does your child experience persistent symptoms, and are they particularly pronounced during the winter months and in the evening, at night and in the morning?

Then it may be time to talk to your doctor, who can examine your child and make a diagnosis.

No, house dust mite allergy can cause the same symptoms. The difference is that the symptoms do not only occur during a particular season, but are present all year round.

House dust mites neither bite nor sting, and because of their microscopic size they cannot be felt on the skin. However, if your child has an allergy to house dust mites, they may experience common symptoms such as itching in the nose and eyes.

House dust mites also have the ability to penetrate damaged skin and affect the immune system. The allergy can therefore also worsen childhood eczema (atopic dermatitis), which appears as itching and dry, red skin. Like house dust mite allergy, childhood eczema is typically also most troublesome at night and during the winter months.

A child with an allergy to house dust mites typically experiences symptoms in the upper airways in the form of a runny or blocked nose and sneezing attacks. Symptoms such as a blocked nose can initially cause the child to breathe through the mouth, giving allergens and other particles free passage to the lungs, where they can cause irritation. In this way, house dust mite allergy – like other forms of hay fever – can spread to the lower airways.

30% of people with hay fever also have asthma symptoms such as coughing, breathing difficulties, wheezing, tightness in the chest, etc.

As house dust mite allergy can affect the lungs and develop into allergic asthma, it is important that the child is examined by a doctor who can make a diagnosis and help bring the allergy under control.

Children with house dust mite allergy can be affected by the allergy all year round. However, some will find that symptoms worsen during the winter months, when humidity is high and children typically spend more time indoors.

The symptoms will often be most pronounced during the time the child spends in bed, where the concentration of house dust mites is highest. The child may therefore experience symptoms that disturb their night’s sleep and result in tiredness the next day, but activities such as playing, pillow fights and tidying up can also cause house dust mite allergens to become airborne and trigger symptoms.

Yes, some do, while others keep it for life, but untreated house dust mite allergy can also develop into much more severe asthma.

No, they are found in all homes. It is not a cleaning problem, but factors such as humidity and access to house dust mites’ preferred food sources (dead human skin cells) that are essential to whether they thrive.

However, there is good evidence that there are fewer allergens in textiles in rooms that are cleaned frequently than in rooms that are not cleaned as often.

It is advisable to vacuum bedrooms once a week and also wipe horizontal surfaces with a damp cloth once a week.

That is not possible. House dust mites cannot bite, as their primary food source is dead skin cells, not blood.

The child also cannot feel them crawling on the skin, as they are microscopically small.

If you suspect a bite, you should check whether the child has instead been bitten by a bed bug.

No. House dust mites can be found in many different places  in your home, including in carpets, curtains, teddy bears,  fabric furniture and clothing.

If you have pets such as dogs or cats, there is also a possibili- ty that the mite lives in their sleeping basket. It is a good idea to wash the pet's blankets along with the bedding.

Exposure during the neonatal period appears to play a particularly important role. People born in autumn have an approximately 50% increased risk of developing house dust mite allergy.

The Danish has changed quite a lot and the English still contains old wording such as “Be smart, not poor!”

Dehumidifiers are often expensive to buy, very noisy and expensive to run.

We have a law of nature that says that if cold air is heated, the humidity falls!

So if you live somewhere where the outdoor temperature in autumn, winter or spring falls below 15°C, you can lower the humidity in your home simply by airing it out. (At an indoor temperature of 21°C.)

Option 1. If you do not already have them, make sure you have fresh-air ventilation (non-electric) in all living areas and bedrooms. These are available for walls, doors and windows. Combine this with an electric fan in the bathroom and a good cooker hood, and make it a habit to leave all doors open.

Combine this with ventilation three times a day for 10 minutes with doors and windows open, so that you create a draught.

The result: Your home will be able to breathe, creating a good indoor climate with low humidity and therefore fewer house dust mites.

Option 2: If option 1 is not possible, you should ventilate at least three times a day for 10 minutes with doors and windows open to create a draught.

The result: The indoor air is replaced, but the short period does not cool down the walls and ceilings, so it does not add to the heating bill.

Option 3: This also means that it is not possible to lower the humidity naturally in areas and seasons where outdoor temperatures are above 15°C.

Result: The only way to avoid house dust mite allergens is to use an allergen-proof cover.

Here can be a brief overview of the information available in this section, explaining its purpose and how users can interact with it.

Yes, a lot. House dust mites live in the upper 5-7 cm part of  the mattress, and most studies suggest that the use of a mattress topper can lower the number of mites by up to 40%.

No, they are so small (0.3 mm) that you need a magnifying glass to see them. If you see mites without magnification, they may be a different kind of animal! For example, bed bugs.

House dust mites eat molds, fungi, dead mites, bacteria, pollen, or just about anything organic, but their favorite food is moldy old, discarded skin scales.

Over 6-8 years old for allergy sufferers. However, if the mattress has not been in humid conditions or has been provided with allergen-proof covers, it may not be a home for dust mites.

To turn hard-to-digest food into a light meal, the mite places active digestive enzymes in its dry excrement. These enzymes remain in the excrement until they meet a moist surface. If the moist surface happens to be delicate human tissue like the mucous membrane of the nose, the enzyme will also start working there.

This action can result in allergies, immune responses, or illness.

Yes, children are recognized as the most vulnerable group suffering from house dust mite-related allergic diseases. Not only because they spend more time in bed sleeping (the mites' favorite home), but because they are often unable to identify allergy symptoms - and as little ones they also cannot understand the need for solutions.

Yes, if they are not disturbed. With the presence of moisture and plenty of food, mites will multiply on top of all covers. It is important to vacuum and wash the covers regularly at 60°C to prevent this.

No, it is not possible! House dust mites cannot bite and they do not drink blood, but enzymes in their excrement can damage or kill delicate cells and cause a breach of the cell defences – for example, in eczema children.

Maybe the bite is caused by another insect, such as a bed bug?

House dust mites can cause allergic rhinitis (hay fever), asthma, eczema and other related diseases. 

They have also been linked to conjunctivitis, limear, urticaria, dermatitis, anaphylaxis, hypersensitive pneumonia, angioedema, extrinsic allergic alveolitis, allergic headaches and migraine headaches, as well as certain intestinal disorders in which Ige is involved. 

Allergy testing is always recommended to confirm a clinical diagnosis of health problems caused by mite exposure.

There are several dust mite test kits on the market. 

Unfortunately, we find that none of them are particularly trustworthy, as they show too many false-positive or false-negative results.

Instead, think as many Danish allergists do, and just assume, 

that you have dust mites, because they are everywhere.

A prick test is a method of introducing a small amount of allergen in the body to measure the strength of any allergic reaction. 

The time of reactions can start 5 minutes after the test and peak about 30 minutes later. Any reactions are observed and recorded as an allergy trigger if the patient has accompanying allergy symptoms. 

It is important that this diagnostic tool is administered by a doctor.

It is more accurate to have your antibodies tested in a blood test.

The first step is to learn how the mite lives and then learn what measures to take to make sure it is not welcome in your bed.

Cover your mattress, pillows and duvets with allergen-proof microporous woven material.

Remove carpets and clutter. Do not make your bed in the morning. Air out three times a day for 10 minutes with doors and windows open so that you create a draught.

If you use an old pillow, the mites will still be inside, even if you put an allergen-resistant cover on.

It is best to have new pillows with a new allergen-proof cover.

The same goes for duvets.

It is clearly recommended that all beds be made mite free. 

Especially if your child also sleeps in your bedroom. 

As a minimum, use very tight mattress and pillowcases as a supplement to a mattress pad. If your house dust mite allergy is severe, protection of the duvet is also recommended.

The mite lives in the nature if there is sufficient food, temperature and moisture. It can spread by clinging to fabric, clothing, fur, feathers or something else that gives them a place to hide and a lift to a new home.

House dust mites die if they are exposed to UV light. They therefore hide away from the light and burrow into the mattress, clinging on with strong hooks and suction cups on each of their eight legs.

Vacuuming a mattress will reduce the number of mites considerably, but never enough to have a major effect. The vacuum cleaner used should be fitted with a HEPA filter.

We recommend investing in protecting the entire bed and bedding to achieve the best possible result for your house dust mite allergy.

Yes! But not as an independent cure. You also need to lower the humidity in the cold season, and maybe introduce some new habits like airing.

It is likely. Three of the most important features of human life are heartbeat, breathing and sleep.

An active house dust mite allergy can interfere with breathing and sleep. Wheezing, sneezing or itching caused by an allergic reaction are also known to affect sleep.

Poor sleep can result in poor concentration during the day.

Yes, ultrafine diesel particles from traffic can carry grass, grass pollen and house dust mite allergens deep into the lungs and nose.

No, living with house dust mite allergy is like having a constant, irritating cold, and it affects your everyday life – all year round.

Some do, while others keep it for life. Unfortunately, untreated house dust mite allergy can develop into asthma which can be very serious.

It is not the amount of dust, but factors such as humidity and access to house dust mites’ preferred food source, such as dead skin cells from humans and pets, that determine whether they can thrive.

House dust mites are microscopically small and are approximately the size of a dot made with a very sharp pencil. An alternative could be bed bugs.

No, dust mites can be found in many places in the home, including carpets, furniture, curtains, teddy bears and clothes.

As summer draws to a close and temperatures drop, House dust mites shelter indoors. So autumn and winter are the seasons where they are most numerous.

It makes no sense to fight them in the summer, as they are everywhere - both outdoors and indoors. They can best be controlled by lowering the humidity when the outside temperature is 15°C or below.

Washing, even with cold water, removes up to 80% of dust mite allergens, while requiring at least 55-60°C hot water to kill the mites.

This is unlikely, as only very few people cannot tolerate down/feathers. After all, it is keratin, just like our nails are made of.

It is much more likely that dust and impurities in the duvet are causing the symptoms, so try a different duvet for a period of time.

New studies show that there are probably fewer allergens in duvets with down than in duvets with synthetic filling.

If left on during the day, it can reduce concentration of dust  mites by approximately 50% as the heat lowers the humidity. 

Although there are no systematic studies on it, it is logical to recommend thorough airing of bedding and mattresses after use, so that the added moisture is quickly removed and the temperature is reduced.

In Denmark, moving to new, well-insulated homes with ventilation systems with heat recovery has been shown to reduce the concentration of house dust mites in both mattresses and house dust. But even under such optimal conditions, it was only possible to reduce the concentration to below 100 house dust mites/g in fewer than 50% of the mattresses.

In a similar recent English study, the ventilation system was able to reduce humidity, but not sufficiently to reduce the concentration of mites or mite allergens.

Effective protection requires several measures that cannot stand alone, and all studies show that the combination of low humidity and allergen-proof covers provides the best solution.

Air-conditioning systems, which reduce the water content of the air, also reduce allergen concentrations during the summer months, and electric dehumidifiers in bedrooms can locally reduce high allergen concentrations in humid climates. However, their noise levels and high costs limit their use. If the dehumidifier is placed elsewhere in the home, it is, like chemical dehumidifiers, ineffective.

Most importantly – smooth floors and no fitted carpets! If the indoor climate has allowed mites to grow in a mattress, a fitted carpet in the same room will also contain allergens.

Beds should have legs to provide good ventilation, so they are raised above the floor. It is not advisable to store bedding in boxes under the bed.