Allergen immunotherapy (AIT) was not recognized as a well-established disease-modifying treatment for allergic disorders. Its role in allergic asthma, spanning from prevention to improving asthma management, remained unknown. Following numerous well-designed randomized controlled trials (RCTs) with house dust mites (HDM) sublingual (SLIT) tablets in asthma, the global initiative for asthma (GINA) recommendations underlined the importance of treating the allergic component of asthma in 2017. The European Academy of Allergy and Clinical Immunology issued the first comprehensive guidelines for HDM AIT in allergic asthma in 2019, with recommendations for subcutaneous, SLIT drops, and SLIT tablets separately. Significant progress had been made in understanding the mechanisms of allergic asthma, simplifying the stratified method for identifying responders, and converting the immune-modulation impact into long-term management of chronic inflammation in asthma.

AIT was recommended as a therapeutic option in the treatment of managed or partially controlled HDM allergic asthma. There was a scarcity of data on pollen, molds, and pets, as well as for those with severe allergic asthma. For further studies, researchers aimed to identify the subgenotypes of allergic asthma that react to AIT, as well as the mechanisms that facilitated its preventative and disease-modifying effects, as well as the appropriate length of treatment and method of administration.