The safety of sublingual immunotherapy with one or multiple pollen allergens in children.

Background: Since the majority of allergic patients are polysensitized, it is often necessary to prescribe immunotherapy with multiple allergens. It is crucial to know if the administration of multiple allergens with sublingual immunotherapy (SLIT) increases the risk of side-effects in children.

Methods: Consecutive children with respiratory allergy because of pollens, receiving SLIT for multiple or single allergens were followed-up in a postmarketing survey. Inclusion criteria were those for prescribing SLIT according to guidelines. Parents recorded in a diary card the side-effects (eye symptoms, rhinitis/ear itching, asthma, oral itching/swelling, nausea, vomiting, abdominal pain, diarrhoea, urticaria, angioedema and anaphylaxis). The side-effects were graded as mild, moderate and severe.

Results: Four hundred and thirty-three children (285 male, age range 3-18 years) receiving SLIT were surveyed. Of them, 179 received a single extract, and 254 multiple allergens. The total number of doses given was 40 169 (17 143 with single allergen). Overall, 178 episodes were reported. Of them, 76 occurred with the single allergen (42.46% patients, 4.43/1000 doses) and 102 (40.3% patients, 4.42/1000 doses) with multiple allergens (P = NS). 165 episodes (92.5%) were mild and self-resolving and were equally distributed in the two groups. In 13 cases, the events were judged of moderate severity and medical advice was required. Three patients discontinued SLIT, despite the local side-effects being mild. No emergency treatment was required at all.

Conclusion: The use of multiple allergens for SLIT does not increase the rate of side-effects in children.