Abstract
Allergen-specific immunotherapy (AIT) has been used to treat allergic diseases for over a century. It is the only treatment that addresses immune dysfunction underlying allergic responses rather than simply treating symptoms or suppressing inflammation. Its safety and efficacy in allergic rhinitis, asthma and insect allergy has been documented in a number of systematic reviews but its cost effectiveness is less clear. AIT reduces symptoms and requirement for medication, while improving quality of life. Further, the effect continues for years after discontinuation of treatment. However, evidence regarding cost effectiveness is limited. During AIT, allergen extracts are administered through a subcutaneous or sublingual route for 3-5 years. Subcutaneous immunotherapy is more effective in inducing long-term remission but systemic reactions do occur occasionally. Sublingual immunotherapy is safer and more convenient for the patient but evidence regarding its long-term efficacy is patchy. AIT is used widely in western Europe and the USA. In the UK, subcutaneous immunotherapy is often used for bee and wasp allergy, while both subcutaneous and sublingual immunotherapies are used for severe allergic rhinitis and occasionally for house dust mite and pet allergies. In conclusion, AIT is safe and effective and should be considered as a treatment option for those with allergic diseases.