There has been a recent increase in the incidence of allergies and the severity of allergic reactions worldwide. Most allergy treatments, such as antihistamines, only treat the symptoms of the allergy. In contrast, allergen-specific immunotherapy (ASIT) refers to a pathogenetic treatment that prevents the progression of allergies. ASIT can also reduce the risk of mild reactions, such as allergic rhinitis, worsening into more serious conditions, such as allergic bronchial asthma. ASIT is performed by administration of an allergen, usually either subcutaneously or sublingually. Sublingual administration is regarded as safer than subcutaneous administration because of a reduction in the risks associated with systemic effects. The uptake of allergens by the mucous membranes in sublingual administration can be improved using delivery agents, such as liposomes, dendrimers, and nanoparticles. Glycyrrhizic acid can self-associate to form micelles and thus, form complexes to enable the delivery of poorly soluble drugs. In addition, glycyrrhizic acid has been shown to have anti-inflammatory effects and is itself a potential treatment for allergic diseases such as allergic rhinitis and asthma. Thus, the development of an ASIT using glycyrrhizic acid is of interest. Herein, we review allergic bronchial asthma and allergic rhinitis and the use of ASIT in the treatment of these conditions. We then discuss glycyrrhizic acid and the potential development of delivery agents using glycyrrhizic acid for use in ASIT.