Purpose of review: The main feature of allergen-specific immunotherapy is its capacity to modify the natural history of the disease, reducing the development of asthma and new sensitizations after 3–4 years of treatment. For this reason, adherence to the therapy is mandatory, as happens for all chronic medical treatment.
Recent findings: Though subcutaneous immunotherapy is administered directly by physicians, the rate of adherence is surprisingly low, at less than 70%. The explanations for a poor subcutaneous immunotherapy adherence include inconvenience, lack of efficacy, costs and loss of working hours.
Local nasal immunotherapy has a very low adherence rate (27%), due to the local nasal side effects.
For sublingual immunotherapy, data are available from clinical trials and postmarketing surveys, which are favourable overall (rates of compliance >75%). Cost was the most common reason for discontinuation, followed by inconvenience, feeling of inefficacy and side effects.
Summary: Studies addressing the adherence to allergen-specific immunotherapy in literature are lacking. In real life, costs and patient education are crucial issues in conditioning adherence to this treatment. Reduction of costs and more efforts in education of patients and also specialists may improve the adherence to immunotherapy.