Dust mite allergy

In dust mite allergies, it isn’t the dust itself that causes the symptoms. Instead, the allergy is triggered by allergy-causing substances (allergens) that are mainly found in the dust mites’ feces. The dust merely spreads the tiny particles of feces.

No home is completely free of dust mites. They are found in beds, carpets, rugs, upholstered furniture and curtains. Because of this, people who have a dust mite allergy have allergy symptoms such as sneezing and a runny nose all year round. If someone has an allergic reaction that affects their upper airways, it is called “allergic rhinitis”.

People who have a dust mite allergy sneeze a lot, and have a runny or stuffy nose. If their symptoms are more severe, they might also feel weak and tired. Their eyes might also water and itch, and they might have swollen eyelids. Asthma-like symptoms such as coughing, wheezing and shortness of breath may also occur.

Dust mite allergies usually cause milder symptoms than hay fever (a pollen allergy) does. But they occur all year round. The symptoms are typically worse at night and in the morning because dust mites tend to live in mattresses, pillows and bedding.

Allergy symptoms arise when your body overreacts to particular substances that are usually harmless. These allergy-causing substances (allergens) trigger a chain reaction in the immune system. First, the body makes antibodies to fight the allergen, and the antibodies bind to specific cells. If these cells come into contact with the allergen again, they are then able to “respond” by releasing chemical substances such as histamine. These substances then set off an allergic reaction, causing symptoms such as sneezing or itchy eyes.

It’s almost impossible to avoid contact with dust. If dust is stirred up – for instance, by a draft of wind or when shaking out bedding – it floats through the air and is breathed in, together with the allergens on it.

Sometimes a higher risk of allergies runs in families. Environmental factors such as air pollution and cigarette smoke can make allergies more likely too. 

Allergic rhinitis affects about 1 out of 4 people in industrialized countries like Germany. Most people develop the allergic reaction before the age of 20.

Dust mite allergies very often first develop in childhood or puberty, and never go away again. If a person suffers from allergic rhinitis for many years, an “allergic march” may occur. This term describes the progression of the allergy, whereby the symptoms move from affecting the upper airways to affecting the lower ones, causing asthma.

Severe symptoms can increase the risk of secondary conditions such as sinusitis. Allergic rhinitis often makes the mucous membranes that line the airways overly sensitive in general too. This can also cause symptoms as a result of irritants like cigarette smoke and dry air in heated rooms.

The most effective way to prevent allergy symptoms is to avoid the substances that trigger the allergy. Although dust mites can’t be completely avoided, contact with them can be reduced. Particularly in the bedroom, it may be helpful to combine a number of different approaches, including

• wiping the bedroom floor with a damp cloth,
• using mite-proof mattress covers,
• removing “dust traps” such as upholstered furniture and curtains, and
• regularly washing your bedding at temperatures above 60 °C.

Dust mites survive longer in warm and humid conditions. So it can be a good idea to keep the bedroom temperature lower than 18 to 20 °C, and regularly open the windows to let fresh air in. Air humidifiers and plants can make it easier for dust mites to thrive, so it’s best to keep them out of bedrooms.

Dust mite sprays containing acaricides (pesticides against mites and ticks) could also help reduce the symptoms. People with a dust mite allergy can spray them onto mattress covers, for instance. It isn’t clear how effective special dust mite air filters are.

Doctors usually first ask the patient about their symptoms, circumstances in life, and medical history. The doctor can then do an allergy test (a skin prick test) to find out whether they are allergic to particular substances. This involves placing small drops of various allergens on different parts of their forearm, and then gently pricking the skin, so the substances go into the skin. If the skin becomes red and swollen (like a big mosquito bite) where it was pricked, it’s a sign that the person is allergic to that substance.

The patient might also need a blood test or a “provocation test” to aid the diagnosis. The latter involves exposing the membranes lining the nose or eyes to extracts of the potential allergen using a nasal spray or drops. If the lining of the patient’s nose becomes swollen, they sneeze and their nose starts running, they are likely to be allergic to that substance.

Various medications are available for the treatment of dust mite allergy symptoms, including:

• antihistamines
• corticosteroids
• chromones (mast cell stabilizers)
• leukotriene receptor antagonists
• decongestant nasal drops and nasal sprays

There are also non-drug alternatives such as saline (salt water) nasal sprays and nasal washes (nasal irrigation). Although these can alleviate symptoms, they cannot usually fully replace medication. 

Allergen-specific immunotherapy (also known as desensitization) can reduce the sensitivity of people with dust mite allergy to allergens over the long term. A bit like with vaccines, this treatment approach involves regularly injecting people with low doses of the allergen under the skin or placing it under the tongue. This treatment lasts at least three to five years.

For more detailed information, for example about desensitization (specific immunotherapy) in allergic rhinitis, visit gesundheitsinformation.de.

Further information about the dust mite allergy condition can also be found at allergieinformationsdienst.de (in German).