Purpose of review: Sublingual immunotherapy (SLIT) is effective in allergic rhinitis and asthma. Apart from its efficacy, safety is crucial as this treatment is usually self-administered at home. Tolerability also plays a pivotal role, as mild local reactions, although not life-threatening, may represent a risk for treatment withdrawal and can therefore negatively affect clinical outcomes. The present study addresses this issue by reviewing double-blind, placebo-controlled, randomized trials and real-life studies.
Recent findings: The number of life-threatening SLIT-related reactions is negligible. SLIT-related adverse events are not always consistently reported nor uniformly classified in published studies. However, systemic reactions are rare and side effects mostly consist of mild, self-limiting local reactions. No treatment-related risk factors for adverse events have been clearly defined, as far as type of allergen, dose or schedule.
Summary: SLIT provides an optimal safety profile both in children and in adults. Apart from life-threatening reactions, the lack of standardization of adverse events reporting may account for the wide variability of the prevalence of side effects in clinical trials and in real-life setting. It can lead to a possible underestimation of adverse events, concerning, in particular, local reactions. Since poor tolerability may affect adherence and cause treatment discontinuation, adopting shared strategies in order to recognize, grade and manage adverse events is mandatory.