Sublingual immunotherapy (SLIT) is useful in the treatment of allergic rhinitis and asthma. Aside from effectiveness, safety is critical because this medication is typically self-administered at home. Tolerability is particularly important, because modest local responses, while not life-threatening, may provide a risk for treatment discontinuation and hence have a detrimental impact on clinical results. This problem was addressed in the current study through a review of double-blind, placebo-controlled, randomized trials and real-life investigations. The number of life-threatening SLIT responses was minimal. In published research, SLIT-related adverse events were not always consistently documented or characterized uniformly. However, systemic responses were uncommon, and most side effects were modest, self-limiting local reactions. There were no well-identified treatment-related risk factors for adverse outcomes, such as allergen type, dosage, or schedule.

SLIT has an excellent safety profile in both children and adults. Aside from potentially fatal responses, the absence of consistency in adverse event reporting may explain the vast range in the occurrence of side effects in clinical trials and in real-world settings. It may result in an underestimate of harmful consequences, particularly local responses. Because poor tolerability can impair adherence and lead to treatment termination, it is critical to have common techniques for recognizing, grading, and managing adverse events.