Sublingual immunotherapy: what have we learnt from the ‘big trials’?

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Abstract
Recent systematic reviews support the use of sublingual immunotherapy for allergic rhinoconjunctivitis in adults, whereas data in children have been less convincing. The present review evaluates three recent ‘definitive’ trials in adults and one in children. Two large independent randomized controlled trials of grass allergen tablets have confirmed the efficacy of sublingual immunotherapy in adults with seasonal allergic rhinoconjunctivitis. Effects were both allergen dose-dependent and time-dependent. Tablets were well tolerated and equally effective in monosensitized compared with polysensitized patients and in patients with peak seasonal asthma (patients with perennial asthma were specifically excluded). Local side effects were common but largely self-limiting and not bothersome. There were no serious treatment-related adverse events. Results were similar in magnitude to those observed in a comparable study of subcutaneous immunotherapy using an alum-based vaccine. A trial of sublingual drops in children with hayfever in a primary care setting was negative, although these results could not be generalized. Sublingual immunotherapy represents an effective and well tolerated treatment for seasonal allergic rhinoconjunctivitis in adults. Current ongoing paediatric trials and evaluation of long-term effects in adults will further define its role in therapy.