House dust mite (HDM) allergy is a common cause of eczema and hay fever. In patients that have symptoms all year round rather than just in spring or summer months, HDM is often the cause.

Avoiding HDM in the UK is very difficult to do. There are lots of different products sold to reduce it, but very often these do not work for all. For many people their symptoms are mild and can be controlled with antihistamines, nasal sprays and eye drops. If symptoms are severe and are interfering with your day to day life your doctor may recommend HDM desensitisation (d-sen-si-ti-za-tion)

What is desensitisation (allergen immunotherapy)?

Allergic reactions take place when the body reacts to foreign proteins, which we call allergens. HDM and pollen are common allergens. By giving patients increasing amounts of the allergen, starting with a very small amount and working up to larger amounts over a period of a few weeks, the body can be trained to ignore the protein. Thus desensitisation dampens down but does not usually completely cure the allergy.

What is house dust mite immunotherapy (HDM SLIT)?

HDM SLIT is a once daily sublingual treatment given three times a week. It is used in patients with severe allergy to house dust mite and comes in the form of drops which are placed under the tongue. HDM SLIT contains a tiny amount of HDM. By daily administration of the drops over a period of months to years, the immune system can be taught to ignore the allergen.

How do I use sublingual immunotherapy?

HDM SLIT comes as drops. The first dose will be given in hospital under close supervision and you will be shown exactly how to take the treatment.

How long will the treatment last?

The treatment will last for three years.

What happens if I miss a dose?

You should not have any side effects if you only miss a few doses. However not taking your medicine regularly will affect how well the medicine works and you may get a return of your hayfever/asthma/eczema symptoms.

What are the alternatives?

Immunotherapy is the only treatment which specifically targets the underlying cause of an allergy. The alternative is to continue with medicines that suppress the symptoms such as anti-histamines and steroids.

Are there other benefits of immunotherapy?

HDM immunotherapy is expected to improve your quality of life and reduce medication use by about one third to one half. It is rarely a complete cure. It is also possible that allergen immunotherapy may prevent new allergies developing and reduce the likelihood of getting asthma. The beneficial effects of the immunotherapy are likely to last for at least 3 to 5 years after finishing the course of treatment.

What are the risks?

Sublingual immunotherapy is very safe. Large studies on hundreds of children have never found any serious reactions. The most common side effects were itchiness and swelling in the mouth after taking the drops. This can be helped by taking antihistamines beforehand, or if the symptoms are recurrent, reducing the dose. Studies from Europe report that side effects are very rarely troublesome enough for the patient to stop the treatment.

How do I know if sublingual immunotherapy will work for me?

At the clinic visit, adetailed history will be taken and skin prick tests will be performed to house dust mite and other allergens. If you are sensitised to HDM and can reliably take the drops every day then HDM SLIT might work for you.

You will probably need to take the drops for 3 to 4 months before you notice any improvement.

Every month, your doctor will check your quality of life score, how bad your symptoms are and the amount of other medication you need to take.

Further information

You will have the opportunity to discuss any issues during your visit to the Allergy clinic. After this, you can call the children’s allergy service during office hours on 0161 701 5422 to speak to one of the specialist allergy nurses.