House Dust Mite Avoidance

HDM allergy commonly causes hay fever-like symptoms all year round, such as sneezing, coughing, itchy watery, red eyes, or runny nose. It can also trigger asthma attacks and eczema.

These tiny creatures are distant relatives of spiders! They thrive in warm (26°C) damp conditions and feed on shed skin scales. They are found in all UK homes no matter how clean. The protein that leads to the allergy is present in HDM faeces (poo).

Faecal pellets are about the same size as pollen grains and it is therefore not surprising that mite allergy and pollen allergy cause similar symptoms – pollen allergy being a seasonal problem, while mite allergy can be a problem all year.  HDM allergy is not related with severe / life threatening allergic reactions, though its link to asthma can be important.

Four out of five patients with allergy to HDM are also allergic to other allergens in the air such as pollens and animals.

The diagnosis of HDM allergy can often be made based on a history.

Positive allergy tests skin prick or blood allergy antibody (IgE) tests support the diagnosis of HDM allergy but should not be used alone as children can have positive allergy tests without getting a reaction. Tests are usually negative in children with delayed reactions. Skin prick tests are safe. They can be done in clinic provided that the child has not had any antihistamines for a few days. Blood tests are not affected by antihistamines, but results are only available a week or so after the clinic appointment.

The diagnosis of HDM allergy can often be made based on a history.

Positive allergy tests skin prick or blood allergy antibody (IgE) tests support the diagnosis of HDM allergy but should not be used alone as children can have positive allergy tests without getting a reaction. Tests are usually negative in children with delayed reactions. Skin prick tests are safe. They can be done in clinic provided that the child has not had any antihistamines for a few days. Blood tests are not affected by antihistamines, but results are only available a week or so after the clinic appointment.

How to avoid house dust mite?

There is little evidence that any measures lead to an improvement in allergy symptoms and it is not possible to remove completely these creatures and their faeces from the home. Therefore, purchase of expensive equipment or renovations are to be avoided. Some simple measures may however help. These include:

• Avoid damp and dusty places.
• Where possible have wood floor surfaces in bedrooms. Avoid bedrooms with thick pile carpets.
• Remove or reduce clutter and soft toys in the bedroom.
• Dust surfaces regularly with a damp cloth and vacuum weekly.
• Children with HDM allergy should not be in the room when cleaning is done, as dust levels are higher during cleaning.
• Your bed (mattress and pillowcase) is the perfect breeding ground. House dust mite proof covers on the pillow cases and mattresses prevent the mites/their faeces reaching your bedding so they cannot build up, but will be washed away each week.
• Do not sleep on the lower bunk bed

• Firstly, we recommend you try to reduce exposure to HDM, if possible, taking the measures that are simplest and cheapest.
• Secondly, either a long acting non-sedating antihistamine or a nasal steroid spray can be used. Some patients get more benefit from taking both together. These may need to be used regularly for a long time.
• If nasal symptoms persist, your doctor may recommend additional treatment with montelukast. If asthma is troublesome, asthma treatments might need to be revised.

Antihistamines and nasal steroids do not cure the allergy. They just treat the symptoms. Desensitisation (immunotherapy) is sometimes offered for HDM allergy by specialist children’s centres if you still have troublesome symptoms despite taking antihistamines and nasal spray regularly. It can reduce symptoms but does not usually lead to a complete cure. The treatment program is three years long and therefore may not be suitable for all patients.

Most children with HDM allergy will not outgrow the problem. However, symptoms often become more manageable with time, lifestyle changes and use of medication.