What is allergen immunotherapy?

  • Allergen immunotherapy is a long-term treatment for allergic rhinoconjunctivitis (hay fever). It helps to reduce allergic symptoms triggered by the exposure to an allergen (e.g. Pollen). Paradoxically the treatment consists of exposing the patient to increasing quantities of the allergenic substance that causes the symptoms. Immunotherapy consists of introducing small doses of an allergen that the patient is allergic to – this helps the body to overcome the allergy by teaching the immune system to react to allergens in a different way. These changes on the immune system take time and last after treatment has stopped. Immunotherapy may be particularly useful when tablets and/or nasal sprays containing antihistamines or steroids have failed to effectively control the symptoms.
  • Specific immunotherapy is the only treatment that may alter the natural course of allergic diseases whereas other therapies only suppress the symptoms. Allergen immunotherapy reduces symptoms and the need for medications, prevents the development of asthma, reduces the chances of new sensitisations to allergens developing and improve the quality of life.
  • This treatment can be administered under the tongue (sublingually) or by monthly injections under the skin (subcutaneous). Subcutaneous injection immunotherapy has been shown to be highly efficacious for allergic rhinitis and asthma, but its use is restricted to specialist centres. Sublingual immunotherapy should be also initiated by a specialist, but can then continue to be safely administered at home.
  • Subcutaneous immunotherapy is started at very low doses. The dose is gradually increased on a regular basis, until a “maintenance” dose is reached (4-6 months of weekly injections). Once the maintenance dose is reached, the injections are normally given once per month for 3 years. After successful completion of immunotherapy, long-term protection can be expected for a period. Itchiness, swelling, and redness at the site of injection are expected. Systemic reactions such as generalised urticaria (hives) or anaphylaxis occur rarely and need to be treated immediately.
  • Sublingual immunotherapy has been shown to be effective to treat allergic rhinitis and allergic asthma in children and adults and has a very good safety profile. SLIT is taken as drops or tablets, placed under the tongue every day. The first dose must be given at your specialist office under close supervision. The side effects of sublingual immunotherapy are generally mild and limited to local reactions (oral pruritus, edema of the mouth, throat irritation, ear pruritus, sneezing, and swelling of the mouth). These usually decrease within a few weeks and are easily managed with antihistamines.
  • The route of immunotherapy method choose depends on the specific allergic disease, type of allergen triggering the disease, risk of adverse reactions, allergen availability and patient preference. Sublingual immunotherapy is prescribed more frequently because of the ease of administration.