"Allergen immunotherapy is the only therapeutic modality which can affect the natural course of allergic disease; it can also prevent deterioration to asthma in patients with allergic rhinitis."

The first Consensus Position "international guidelines compiled by the world's leading experts in the field" on desensitisation was published in 1997. One of its aims was to define broad rules for the conduct of desensitisation procedures. Included was evidence of the efficacy of the approach and information on improvements made to improve its safety.

The Consensus Position grants allergen immunotherapy its place in the treatment of allergic disease: After patient education and allergen avoidance, allergen immunotherapy is recommended in the treatment of allergy with the same status as that accorded to pharmacotherapy. Allergen immunotherapy has been clearly shown to be the only treatment modality which can divert the natural course of allergic disease, and it has also been shown that it can prevent the development of asthma in patients who suffer from allergic rhinitis.

The Consensus Position defines indications for allergen immunotherapy: The Consensus Position lends its weight to allergen immunotherapy recommended indications for the treatment of rhino-conjunctivitis, allergic asthma and hypersensitivity to hymenoptera venom, recommendations which were established on the basis of published data.

The Consensus Position also defines procedures for desensitisation protocols:

• Prescription: since the response to allergic immunotherapy depends entirely on which allergen is administered, a profound understanding of immunology and allergic pathology is an essential prerequisite in any care provider who is qualified to diagnose allergy and prescribe desensitisation.

•  Administration: administration of an allergen to a hypersensitive patient can induce anaphylactic shock which is why this type of therapeutic product must always be administered by a qualified physician (or at least under the supervision of such) who is capable of recognizing the first signs of anaphylaxis and implementing the appropriate emergency measures.

•  Products: preferably, the allergen extracts used should have been standardised and therefore be of known potency and with a known shelf life.

The Consensus Position recognizes the validity of desensitisation procedures based on sublingual administration

For allergic disease affecting the airways, the sublingual route represents a genuine alternative to subcutaneous injection for administration of the allergen.