Allergen-specific immunotherapy (AIT) is an allergen-specific treatment for people with IgE-related allergies. Allergen-specific immunotherapy (AIT) is used to treat allergic disorders when symptoms persist despite medication and allergen avoidance. The therapy is presumed effective if it reduces the use of medications, improves the quality of life even after discontinuation of treatment, as well as prevents the conversion of one type of allergy to the other and the development of new sensitization. The allergen-specific immunotherapeutic agents can be administered sublingually, subcutaneously, or through some other routes, such as intra-lymphatically and epicutaneously to induce allergen tolerance by modifying immune responses (innate and adaptive). The primary mechanism of AIT is the induction of functional regulatory cells, such as regulatory T cells, follicular T cells, B cells, dendritic cells, innate lymphoid cells, and natural killer cells, which results in the control of the functions of type 2 inflammatory cells. However, there are several downsides to AIT, including the contentious treatment period resulting in high cost, systemic allergic reactions, and the lack of a biomarker for forecasting treatment responders. Vaccine adjuvants, adjunctive therapies, and novel vaccine technologies are currently being researched to address the issues associated with AIT. This article focuses on defined molecular approaches for improving the potential of specific immunotherapy that use recombinant allergen derivatives, allergen-derived peptides, virus-coupled allergens, nanoparticles, and specific adjuvants.