Sublingual Immunotherapy for Allergic Rhinitis and Conjunctivitis

Giovanni Passalacqua; Valentina Garelli; Francesca Sclifò; Giorgio Walter Canonica


Immunotherapy. 2013;5(3):257-264. 

In This Article

Abstract and Introduction


Sublingual immunotherapy (SLIT) for allergic respiratory diseases was first described in 1986 and immediately appeared as a viable alternative to the traditional subcutaneous route. Since then, more than 60 randomized controlled trials have been published, almost all with very favorable results. The average improvement over placebo in symptom score and medication use was always greater than 20%. The results of the clinical trials were pooled in several meta-analyses, which consistently confirmed the efficacy of the treatment. SLIT is characterized by a satisfactory safety profile, its side effects being mainly limited to oral discomfort. Only six anaphylaxes and no fatalities have been so far reported. Due to the good risk:benefit ratio, SLIT is currently being investigated in diseases other than respiratory allergy, such as food allergy and atopic dermatitis.


In 1986 the use of allergen-specific immunotherapy (SIT) administered by the sublingual route (SLIT) was described for the first time.[1] Until then, the only route of administration for SIT remained subcutaneously (SCIT), which was repeatedly demonstrated to be effective in respiratory allergy. Nonetheless, with SCIT, some risk of severe or even fatal adverse events still remains.[2] The risks can be partly attributed to technical/human errors and can therefore be avoided;[3] however, a large fraction of the severe adverse events reported remain unpredictable, even if all precautions are taken. Based on this, alternative routes of administration were repeatedly approached. Among them, SLIT appeared as a promising route, despite initial skepticism owing to the low doses used and the poor design of the early studies.[4] During the last 15 years, numerous randomized controlled trials confirmed the clinical efficacy of this route and several postmarketing surveys supported the good safety profile of SLIT. Nowadays, SLIT is officially accepted in international documents as a viable alternative to SCIT[4–6] for both adults and children. In addition, thanks to the good safety profile, the use of SLIT has also recently been proposed in nonrespiratory allergy, including atopic dermatitis and food allergy.[7]

Despite the abundant literature confirming the efficacy of SLIT, some aspects are still debated, such as the optimal maintenance dose, best administration regimen and duration of the treatment. Finally, the wide variability in standardization methods, usually applied using in-house references, render the published studies difficult to compare.