Sublingual immunotherapy in allergic rhinitis: efficacy, safety, adherence and guidelines

Allergic rhinitis (AR) is a globally increasing health problem affecting the quality of life. Specific immunotherapy is an available causal treatment changing the basic allergic mechanisms of the disease. Over one hundred years, subcutaneous immunotherapy (SCIT) was developed and proved its efficacy but many adverse effects were recorded including anaphylaxis. In 1986, sublingual immunotherapy (SLIT) was introduced as an alternative solution to solve this problem. Our study aims to discuss SLIT from the points of efficacy, safety, adherence and guidelines developed. A literature search was conducted in Medline/PubMed and the Cochrane Library in January 2013 using the keywords "allergic rhinitis, sublingual immunotherapy, efficacy, safety, compliance, adherence, guidelines." All types of publications were included. We augmented our study by searching the reference lists of identified reviews. SLIT has been established in many guidelines as an evidence-based effective treatment in AR with safer profile than SCIT. The meta-analyses confirmed its efficacy and showed a significant reduction in both symptoms and medication scores. The most common recorded adverse effects were minor local effects in the mouth, gastrointestinal reactions with few cases of anaphylaxis and no fatality. Adherence is more favorable for SLIT mainly because it is safe, noninvasive and easily taken at home. We support the call to conduct large multi-centric studies to gain more statistical power and overcome the problem of heterogeneity observed in the meta-analyses.