Immunotherapy: Allergen Desensitisation

Immunotherapy medications

Allergy management has always involved avoidance of what you are allergic to in combination with treating the symptoms with long term medications. However, while such avoidance measures and treatments may be effective they do not alter your allergy itself. In other words, you remain allergic 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. Immunotherapy offers the chance to desensitise you to your allergy and eliminate your symptoms for life.

What is Immunotherapy?

Immunotherapy is a desensitisation treatment course for allergies where a daily dose of allergen is taken in order to generate immune tolerance and desensitisation to the specific allergy. Immunotherapy is available in oral sublingual forms (SLIT) and in subcutaneous injections (SCIT) but in Ireland we primarily use the oral sublingual forms. The treatment duration is approximately 3-5 years but significant improvements are expected within the first year. The results typically last for life.

Which Allergies 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:

What Medical Conditions is Immunotherapy be used for?

Immunotherapy can be used to prevent 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.

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. 

What age groups can use Immunotherapy?

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 over the age of 6.
  • 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 carried out?

Skin Prick Allergy Testing is carried out to identify the culprit inhalant allergy. The first dose is taken under medical supervision and thereafter the patient dissolves a tablet under the tongue once daily. The treatment duration is typically 3 to 5 years but improvements are expected within the first 6-12 months. 

What are the advantages of Allergen Immunotherapy?

  • It provides long term and even lifelong symptom relief. 
  • Reduces nose, eye and chest sensitivity to allergic irritation.
  • Reduces or eliminates the need for medication.
  • Allergen desensitisation is not a drug and can therefore be continued during pregnancy.
  • Grazax is available on the drugs payment scheme. Acarizax is currently being considered for inclusion.

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 before starting Immunotherapy

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 can aggravate rhinitis symptoms so if you don't stop smoking this will reduce the overall impact of using immunotherapy.

Our doctors ensure that before rushing into starting treatment we consider all of the issues outlined above so that you make an informed decision that's right for you.

Further Information