Post-market Clinical Follow-up Study of an Isotonic Saline Solution to Manage Nasal Congestion in Case of Flu Symptoms, Colds, Allergic Rhinitis and Rhinosinusitis in Infants and Toddlers

The goal of this observational post-market clinical follow-up study is to evaluate the safety and performance of the CE-marked nasal spray in the management of nasal congestion in case of flu, colds, allergic rhinitis and rhinosinusitis in infants and toddlers aged 3 to 48 months at day 5 post-enrolment. Enrolment does not require establishing a medical diagnosis; eligibility is based on guardian-reported nasal congestion consistent with lay use of the device. Participants will be: * Evaluated by a healthcare professional for eligibility. * Receive treatment with the CE-marked nasal spray according to its Instructions for Use, for up to 14 days. * Have their legal guardians report symptom severity and improvement using standardized scales (Visual Analog Scale) during follow-up visits on Day 2, Day 5, and Day 14 and device usability on Day 14. This study does not include a comparison group and reflects real-world use of the device in routine pediatric care.