Allergic rhinoconjunctivitis is a pathology of the nasal and conjunctival mucosa induced by Immunoglobulin E (IgE) mediated inflammation following allergic exposure. This condition represents a global health problem that affects 5 to 20% of the population. As with all allergic diseases, its prevalence in pediatric age has increased over the last 30 years, as shown by the results of the international epidemiological study International Study of Asthma and Allergies in Childhood (ISAAC) which shows that the overall prevalence is 8.5 % in children aged 6-7 and 14.6% in children aged 13-14. In Italy, on average, the prevalence stands at 17.6% in the 6-7 year age range and 31.3% in the 13-14 age range, demonstrating a growing trend. The allergic rhinoconjunctivitis undiagnosed and / or not treated properly can negatively affect the school activities and in general the quality of life of children and their parents, as well as having important socio-economic repercussions in terms of medical expenses, school absences and days of work lost by parents. Furthermore, the lack of therapeutic intervention can lead to an increased risk of complications in the medium and long term. Recent advances in the understanding of the mechanisms underlying the inflammation of the airways have led to an improvement of the therapeutic strategies for the management of allergic rhinoconjunctivitis: the four cornerstones of the approach to this pathology promoted by the European Academy of Allergy and Clinical Immunology (EAACI) include allergen removal, patient education, pharmacotherapy and specific immunotherapy. However, there is discordant evidence to support their efficacy in reducing the symptomatology of allergic rhinoconjunctivitis, with the need to resort to the invasive surgical approach in several cases. Therefore, the use of probiotics, defined as "live micro-organisms which, when administered in adequate quantities, confer an advantage for the organism" can be useful. The mechanisms by which probiotics or their components, for example DNA, proteins and peptides, exert such beneficial effects concern the regulation of the immune system, the antagonist action against potentially pathogenic microorganisms and the quantitative and qualitative modulation of the intestinal microbiota. In fact, recent clinical studies have demonstrated the protective effect of infections of the high respiratory tract in adults and recurrent average otitis in pediatric age of the Streptococcus salivarius 24SMBc and Streptococcus oralis 89a strains administered through nasal spray. These well-characterized probiotics were safe, tolerated and able to positively modulate the composition of the respiratory epithelial microbiota and the function of the immune system.

Inclusion Criteria:

• children aged 6-12 months with allergic rhinoconjunctivitis

Exclusion Criteria:

• concomitant presence of chronic pathologies,
• malformations of the respiratory tract and facial cranium,
• tumors,
• neurological diseases,
• metabolic pathologies,
• cystic fibrosis,
• immunodeficiencies,
• history of epistaxis,
• alteration of coagulation factors,
• history of apnea,
• ciliary dyskinesia,
• treatment with topical drugs nasal steroids and / or oral anti-histaminics or antibiotic treatment in the 3 months prior to enrollment.