Sublingual Immunotherapy for Respiratory Allergies


This information brief was performed at the request of the Collège des médecins du Québec concerning the clinical efficacy and safety of sublingual immunotherapy (SLIT) for respiratory allergies. These are characterised by an allergic rhinitis, allergic conjunctivitis or allergic rhinoconjunctivitis caused by aeroallergens. Like subcutaneous immunotherapy (SCIT), SLIT is designed to make individuals tolerant to an allergen. Unlike SCIT, SLIT does not require injections, and patients may self-administer the treatment, which involves placing an allergenic product in the form of a tablet or drops under the tongue and keeping it there for a few minutes.  

Conclusions and results

According to the most commonly used efficacy parameters, SLIT produces a significant reduction in all allergic rhinitis and allergic conjunctivitis symptoms, most symptoms specific to allergic conjunctivitis (e.g., eye watering) and the use of medications for allergic rhinitis. However, no significant difference was observed between placebo and SLIT in relation to the use of medications for allergic conjunctivitis as well as all allergic conjunctivitis symptoms and the use of medications for this disorder (combined parameters). SLIT is considered safe in the systematic review on allergic rhinitis that considered this parameter. It is associated with an extremely low incidence of significant side effects and caused no anaphylaxis or deaths. Analyses of the clinical efficacy of SLIT were nevertheless characterized, for the most part, by considerable heterogeneity in the studies under review. In addition, questions were raised on the optimal doses of allergens to use, the treatment schedule to follow, the length of the benefit and the efficacy of mixtures of non-cross-reacting allergens.

INESSS performed a literature review on the clinical efficacy and safety of SLIT and selected three publications with a high level of evidence to reach conclusions.

Further research/reviews required

Although most of the efficacy and safety studies on sublingual immunotherapy for respiratory allergies are reassuring, much is still unknown about introducing this therapeutic modality into clinical practice. To provide relevant answers to the raised questions, large studies need to be undertaken in North America, especially on standardized allergens administered sublingually and in liquid form.

Written by
Geneviève Martin, INESSS, Canada

INAHTA Brief issue: 2013/006

Agency: INESSS, Institut national d'excellence en santé et en services
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