House dust allergy

and Martina Feichter, medical editor and biologist

Sophie Matzik is a freelance writer for the medical team.

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Martina Feichter studied biology with an elective subject pharmacy in Innsbruck and also immersed herself in the world of medicinal plants. From there it was not far to other medical topics that still captivate her to this day. She trained as a journalist at the Axel Springer Academy in Hamburg and has been working for since 2007 - first as an editor and since 2012 as a freelance writer.

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In house dust allergy (house dust mite allergy), the immune system is overly sensitive to certain substances in the excrement of house dust mites. Symptoms such as watery, itchy eyes, runny nose, cough and skin reactions occur. In the worst case, a house dust allergy causes shortness of breath and allergic asthma. Read everything you need to know about the causes, diagnosis and treatment of house dust allergies here!

ICD codes for this disease: ICD codes are internationally recognized codes for medical diagnoses. They can be found, for example, in doctor's letters or on certificates of incapacity for work. J45J30

Brief overview

What is a house dust allergy? A hypersensitivity of the body to certain proteins of the house dust mites. It is therefore correctly called a house dust mite allergy. Colloquially, the disease is also called dust allergy and mite allergy. It usually develops in childhood and adolescence and usually lasts for life.
Symptoms: reddened, itchy and watery eyes, stuffy nose and runny nose, possibly sneezing, allergic skin reactions (itching, rash, hives), sometimes coughing with mucus or progression to allergic asthma with acute shortness of breath.
Treatment: Reduce exposure to mites in your own home (special mattress covers, no carpets, etc.), medication against allergy symptoms, hyposensitization
Frequency: In industrialized countries around one in four suffers from an allergic runny nose, for example caused by house dust mites or pollen.
Prognosis: With consistent treatment, the symptoms can be reduced or eliminated entirely. Over time, however, a house dust allergy can develop into allergic asthma (change of floor). In addition, some house dust allergy sufferers are hypersensitive to crustaceans such as shrimp (cross allergy).

House dust allergy: symptoms

The house dust allergy symptoms are set in motion by the messenger substance histamine. This is released in large quantities through contact with the allergy trigger - certain proteins from house dust mites: it causes the mucous membranes to swell, expands the blood vessels, stimulates the production of mucus and is involved in inflammatory processes. As a result, the various house dust allergy symptoms develop in the eyes, nose, respiratory tract and skin:

Red, itchy and watery eyes are typical symptoms of a house dust allergy. Contact with the allergen triggers conjunctivitis (allergic conjunctivitis).
The nose is often blocked because the mucous membranes swell and more secretion is produced. But it can also run runny nose. Sneezing is also possible.
House dust allergies can lead to a congealed cough (bronchitis) and even to allergic asthma with acute shortness of breath.
On the skin, a house dust allergy can cause symptoms such as itching, rashes and hives. In hives (urticaria), wheals, i.e. small, red swellings, form on the skin.

Because the house dust allergy symptoms appear very quickly after contact of the mucous membranes with the allergen, the disease is an allergy of the immediate type (type I).

All the symptoms of a house dust allergy can also show up in other allergies and other illnesses. For example, runny nose and cough can be misinterpreted as signs of a simple cold. That is why a house dust allergy is often recognized late or not at all.

When do the house dust allergy symptoms appear?

House dust allergy symptoms occur all year round, as house dust mites live permanently in apartments. In late autumn and also in winter, however, the symptoms are usually particularly pronounced. The small arachnids reproduce mainly between May and October. When the heating is turned on in late autumn and the humidity in the rooms drops as a result, the mites die in large numbers (they need a more humid environment). The dead mites and their excreted droppings disintegrate, mix with the house dust and can then be easily inhaled with the air. House dust allergy symptoms therefore occur more frequently in these months than in the rest of the year - especially if there is also seldom ventilation (as is often the case in winter).

During the day, the house dust allergy symptoms are particularly noticeable at night or in the morning after getting up. Mattresses are considered to be the largest mite reservoir.

House dust mixed with dead mites and mite droppings is easily whirled up and then inhaled during activities such as making beds, dusting and vacuuming. The house dust mite allergy symptoms are therefore often particularly pronounced in daily housework.

Cross allergy

The mite proteins, which trigger a house dust mite allergy, are similar to proteins in crustaceans. That is why some house dust allergy sufferers are overly sensitive to shrimp, crayfish and lobster, for example - the consumption of these animal foods can also trigger allergy symptoms in those affected. Doctors speak of a cross allergy in such a case.

House dust allergy: causes and triggers

House dust allergy is triggered by certain proteins from house dust mites. The small arachnids themselves are harmless because they neither suck, sting, bite nor transmit diseases. They are invisible to the naked eye and can generally be found in every apartment, namely in house dust. They feed mainly on human skin flakes. That is why they prefer to romp around in upholstered furniture, pillows, beds and carpets. The mites feel most comfortable at a room temperature of 25 degrees or more and a humidity of 65 to 80 percent.

The proteins of the mites, which trigger the house dust allergy, are mainly found in the faeces, but also in the animals' bodies. When excreted droppings and dead mites dry and disintegrate, they mix with the house dust. If this is whirled up (e.g. when vacuuming or opening the bedspread), it can be inhaled and trigger hypersensitivity reactions in the body of the person concerned.

The real cause of house dust mite allergy is a dysregulation of the immune system:

The first contact with the allergen does not show any allergy symptoms. However, the body produces specific antibodies against the new and supposedly threatening foreign substance. Some of these antibodies are stored in the body. Any further contact with the allergen then triggers the specific antibodies on the plan, and large amounts of histamine are released. This messenger substance sets the mechanisms in motion that ultimately lead to the typical symptoms of house dust mite allergy (red, watery eyes, stuffy, runny nose, etc.).

House dust allergy: treatment

The treatment of house dust allergy mainly consists in reducing the mite load in living spaces. In addition, the symptoms can be alleviated with various medications. A desensitization is recommended against the cause of the house dust allergy - the hypersensitive immune system.

Reduction of the mite load

In the case of a house dust allergy, it is very important to keep the mite load in your own home low. To do this, you should take the following tips to heart:

Put as little upholstered furniture as possible in your apartment, as these only serve as dust catchers. Leather trimmings, for example, are a better alternative here. You should also avoid other dust catchers such as carpets, pillows, cuddly toys, heavy curtains, and open bookcases.
Existing upholstered furniture and carpets should ideally be vacuumed thoroughly once every day. The best thing to do is to use a vacuum cleaner with a special fine dust filter (Hepa filter). Despite this special filter, people who are allergic to house dust should leave vacuuming to someone who is not overly sensitive to house dust mites.
Choose curtains made from washable materials and clean them every six months.
When cleaning the apartment, you should use damp dusters and wipe the floors with a damp cloth. This means that less dust is raised.
Get a mite-proof mattress protector. Such an encasing cover must completely enclose the mattress and should be washed about every three months. If you use such a mite repellent, it doesn't really matter what material the mattress itself is made of. However, a filling made of horsehair is unfavorable: the allergens in animal hair could put additional strain on the immune system in the case of a house dust allergy.
It is best to use cotton sheets and wash them once a week at at least 60 degrees. Bedding and pillows should be washed at least every three months at 60 degrees or more.
There are now detergents with acaricidal substances that kill mites. This allows mites to be killed even at washing temperatures below 60 degrees. How effective such acaricidal substances are in practice cannot be clearly stated: the corresponding study results are contradictory.
If your child has a house dust allergy and does not want to do without his cuddly toy, you should wash it regularly at at least 60 degrees. If it cannot be washed so hot, you should freeze it regularly for 12 hours and then wash it at a lower temperature: the cold kills the mites, washing removes them.
To reduce the humidity, you should ventilate the living rooms daily (for 5 to 15 minutes), especially the bedroom.
If possible, avoid placing potted plants in your home, especially in the bedroom. They increase the humidity, which means that dust mites and mold (which the mites also feed on) thrive better. In addition, molds like to grow on the potting soil.
Tips for your vacation: If possible, look for a hotel that offers allergen-free rooms. If you suffer from a severe house dust allergy, you should also take your encasing for the mattress with you as a precaution. If there is no special allergy-free room, you should remove all plush items if possible and ventilate the room well. By the way: in regions over 1,500 meters above sea level there are hardly any or no house dust mites. The same goes for deserts and the Antarctic.

If the house dust mite allergy is not very pronounced, these measures are often sufficient to permanently reduce the symptoms. Nevertheless, it is advisable to have the contact details of a doctor or an allergy ambulance ready in the event of an emergency. If the house dust allergy symptoms turn out to be particularly severe (especially in combination with acute shortness of breath), medical help must be obtained quickly.

Medicines for house dust allergies

Various medications are available for the acute treatment of house dust allergy symptoms. They are mainly used for severe complaints. Some of the remedies are also available from pharmacies without a prescription. However, it is advisable to consult a doctor for advice before using any medication. Because every remedy can have undesirable effects as well as interactions with other drugs or food.

In principle, you can reduce the symptoms of an allergic runny nose (as it occurs in the context of a house dust allergy) with the following means:

So-called antihistamines generally relieve allergy symptoms by inhibiting the release of histamine. They can be used as tablets or nasal spray for allergic rhinitis.
Glucocorticoids ("cortisone") as a nasal spray have a decongestant effect on the nasal mucous membranes. If necessary, they can be used over a longer period of time under medical supervision.
Nasal drops and nasal sprays with decongestant agents (alpha sympathomimetics) help with a blocked nose. However, they should be used for a maximum of five to seven days. Otherwise, the mucous membrane will get used to it, and the effect of the funds will decrease. These preparations can also cause nosebleeds.
Leukotriene antagonists inhibit messenger substances that play an important role in inflammatory reactions in the airways. In addition to the symptoms of asthma, this can also alleviate the symptoms of allergic rhinitis. The prescription drugs (tablets) can be prescribed to patients who suffer from asthma and allergic rhinitis at the same time.
Mast cell stabilizers (Cromone) prevent the release of histamine from so-called mast cells (a type of immune cell). For allergic rhinitis and allergic conjunctivitis, they can be used as a nasal spray or in the form of eye drops.

Desensitization

With the desensitization (specific immunotherapy) an attempt is made to treat the cause of the house dust allergy. Desensitization is particularly successful in children (from 6 years of age) and in people with a house dust allergy, which has only recently existed.

There are two possible approaches to desensitization:

With subcutaneous immunotherapy (SCIT), the mite allergens are injected under the skin in slowly increasing concentrations - initially usually once a week, later once a month. The body should slowly get used to the actually harmless mite proteins.
In sublingual immunotherapy (SLIT), the mite allergens are usually given once a day as drops or tablets under the tongue, held there for one to two minutes and then swallowed.

In both cases, the following applies: The desensitization must be continued for at least two to three years until it shows its full effect. This then lasts for years. If the symptoms of house dust allergy increase again, the desensitization can be repeated.

House dust allergy: homeopathy also effective?

Various homeopathic remedies should help with a house dust allergy, for example Sticta or Sabadilla. The effectiveness of homeopathy has not been scientifically proven. However, some patients report good results with homeopathic medicines. In addition, homeopathic treatment usually does not show any side effects.

House dust allergy: prevention and tips

So far, no specific measures are known that have been proven to prevent a house dust mite allergy. For example, a mite-proof mattress cover (encasing) cannot be recommended to prevent the development of a dust allergy (primary prevention). However, it is suitable for secondary prevention, i.e. the prevention of allergic symptoms in the case of an existing house dust mite allergy.

However, if you want to reduce your risk of a house dust allergy and other allergies, you can stick to general tips. This is particularly advisable if allergies (of any kind) occur frequently in a family - the related family members probably have a hereditary predisposition to allergies (atopy). For such atopics, it is particularly important to reduce exposure to common allergy triggers such as house dust mites as much as possible.

To do this, you should reduce the mite load in your own four walls. The tips are similar to those for people with an existing dust mite allergy (see "Treatment" section). For example, you shouldn't have too many dust collectors in your living room, vacuum and dust regularly and especially keep the bedroom cool and dry.

Breastfeeding can reduce the risk of allergies in infants. Experts therefore recommend feeding babies exclusively with breast milk for the first four months of life. The later diet also influences the risk of allergies: There are indications that a menu with a lot of vegetables and fruit (Mediterranean diet) can prevent atopic diseases such as house dust allergy.

House dust allergy: course and prognosis

If you consistently reduce the allergen exposure (by using a mattress with an encasing, etc.), the symptoms of a house dust allergy can be significantly reduced or (in mild cases) avoided entirely. Medication can also relieve symptoms. A house dust allergy can be treated causally by means of desensitization. It usually achieves good results: Those affected then need much less allergy medication or even none at all.

A house dust allergy can lead to a change of floor over time: the allergy shifts from the upper to the lower respiratory tract - those affected develop allergic asthma.

House dust allergy: examinations and diagnosis

If a house dust allergy is suspected, an allergy specialist (allergist) is the right contact.

Initial meeting

In the first conversation with the patient, he collects his medical history (anamnesis): He asks, for example, about the type and extent of the complaints, personal living conditions and any other illnesses.

Allergy diary

Because allergic reactions such as watery eyes and runny nose can have many causes, the diagnosis of a house dust allergy is often difficult. The doctor will therefore likely ask you to keep an allergy diary for a while. There you should, for example, enter when and in what intensity the various complaints occur, whether you only make yourself noticeable in your own apartment or in someone else's household and what you were doing or eating before the complaint occurred. This information can corroborate the suspicion of a house dust allergy or point out other possible allergy triggers (such as pets or food).

Allergy test

The next step is an allergy test, usually the so-called prick test: The doctor drips various allergens onto your skin on your forearm or back. Then he lightly scratches the skin in the affected areas. If you are not overly sensitive to an allergen, the skin will not show any changes. In the case of an existing allergy, however, the skin under the relevant allergen will turn red within about 20 minutes or form a wheal (red, usually itchy, small skin swelling).

The responsiveness of the skin can be influenced by various factors such as acute infections or the use of certain medications. With the prick test, a certain allergy such as house dust allergy can neither be clearly proven nor excluded.

Blood test

Another test method for suspected house dust allergy (or other allergy) is various blood tests. Some tests only allow a statement to be made as to whether there is a general allergy or not. Others, on the other hand, are more specific, such as the RAST test, which searches the blood for specific antibodies against certain allergens such as house dust mites.

Provocation test

If a dust allergy cannot be clearly identified with the help of the examinations mentioned, the doctor can carry out a provocation test. He applies the suspected allergen (i.e. mite protein) directly to the patient's nasal mucosa. If an allergic reaction occurs as a result, there is a high probability that a house dust allergy is actually present. It is important that such a provocation test is always supervised by a doctor. If there is a severe allergic reaction, he can quickly initiate appropriate countermeasures.

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