Immunotherapy: Allergen Desensitisation

Immunotherapy medications

Allergy management has always involved avoidance of what you are allergic to in combination with treating the symptoms. For example, in allergic rhinitis triggered by dust mite sensitivity special mattress covers and low allergy pillows are advised in combination with medications such as antihistamines and steroid nasal sprays. However, while such avoidance measures and treatments may be effective they do not alter your allergy itself. In other words, you remain allergic to house dust mite and will still get into trouble if the avoidance measures and treatments are discontinued. This means many years or even a lifetime of taking anti-allergy tablets, sprays, inhalers or even courses of steroids for more severe flare ups. Now a relatively new therapy (or rather an old therapy updated) offers the chance to desensitise you to your allergy and eliminate your symptoms.

What is Immunotherapy?

Immunotherapy is a desensitisation treatment course where a tiny dose of allergen is taken orally in pharmaceutically modified form. This generates immune tolerance and desensitisation to the specific allergy. The treatment duration is approximately 3-5 years. Significant improvements are expected within the first 12 months.

How does Immunotherapy work?

Allergies are characterised by a Th2 (T-helper cell 2) immune response involving an environment rich in IL-4 and IL-13 which induce IgE production from B cells. Allergen specific IgE then attaches to mast cells and basophils which primes them for activation in the event of future exposures to the specific allergen. This is referred to as primary sensitisation. 

Immunotherapy is thought to work through the induction of specific IgG antibody's which compete with the specific IgE antibody's responsible for potentiating the allergic immune response. Immunotherapy also increases the number of allergen specific T regulatory cells and IL-10 which modulates IL-4 production and mast cell activation. These effect begin within 4 weeks of starting treatment and continues to increase during the treatment course. 

Which Allergies and Medical Conditions can Immunotherapy be used for?

Immunotherapy has long been available worldwide in injectable and oral forms for a wide range of allergies. At Allergy Ireland, our doctors use the following oral licensed Immunotherapies:

Immunotherapy can treat all of the symptoms associated with grass pollen, tree pollen and house dust mite allergy. This includes nose symptoms (allergic rhinitis) and eye symptoms (allergic conjunctivitis). It can also prevent pollen or house dust mite induced exacerbations of asthmaeczema and urticaria in susceptible individuals. 

Who can Immunotherapy be used for?

Immunotherapy is very effective in those under the age of 40 but its efficacy is reduced in older people. It is safe for use though pregnancy.

  • Grazax (grass pollen) and Oralair (grass pollen) are licensed for use in over 5's.
  • Acarizax (dust mite) is licensed for use in 12-65 year olds. 
  • Itulazax (tree pollen) is licensed for use in 18-65 year olds.

How is Immunotherapy administered?

A sublingual wafer tablet is dissolved under the tongue once daily. The treatment duration is typically 3 to 5 years but improvements are expected within the first 6 months. 

What are the advantages of Allergen Immunotherapy?

  • Provides long term and even lifelong symptom relief. 
  • Reduces nose, eye and chest sensitivity to allergic irritation.
  • Reduces or eliminates the need for medication.

Is Immunotherapy Safe?

Allergen Desensitisation Immunotherapy is considered a very safe treatment. As immunotherapy is based on modified allergen rather than a drug it can even be continued in pregnancy. The first dose is taken under medical supervision in Allergy Ireland due to the very small risk of an allergic reaction. The rest of the treatment course is taken at home. 

Most side effects are minor and of little significance. Common mild side effects include transient itching in the mouth, swelling of the lips or stomach cramps. These symptoms are almost always prevented by using a daily anti-histamine for the first few months of treatment. It is uncommon for pre-existing allergic rhinitis, asthma or eczema to be exacerbated by immunotherapy. A reduction in dose in these cases usually suffices and allows the treatment to continue.

The potential for adverse effects typically disappears within 3 months of starting treatment as the immune system adapts to become more tolerant.

Additional Considerations

It sounds exciting and is a real alternative to drops, sprays, inhalers and anti-allergy tablets. And yes, it has the potential to provide a long term solution to be a long term problem. But there are some side issues that you should first consider.

  1. How good are you (your child) at following daily routines with medicine? Is it a battle? By starting another daily therapy is there the possibility you’re adding an additional problem?
  2. If the treatment is going to last 3-5 years, how committed are you and your child to that length of therapy? If your son is an obedient 12 year old today could he be a rebellious and possibly anti-medicine 15 year old as therapy progresses? It is important to consider how attitudes may change with time and maturity. 
  3. Immunotherapy targets the allergic factor in nose, sinus, skin and chest conditions. However, sometimes there are other triggers in these conditions. For example, smoking causes rhinitis symptoms so if you don't stop smoking this will reduce the overall effect of using immunotherapy.


In summary, undertaking a course of immunotherapy requires patience, commitment and attention to other trigger factors to ensure the best results. Our doctors will ensure that before rushing into starting treatment patients consider all of the issues outlined above so that you make an informed decision that's right for you.

Further Information