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

Inclusion Criteria: * Male and female infants / toddlers aged 3 to 48 months (inclusive) at the time of enrolment. * Subjects with flu, cold, allergic rhinitis or rhinosinusitis as reported by their legal guardian(s) and/or medical history. * Subjects presenting at least moderately bothersome nasal congestion (blocked or stuffy nose) as reported by their legal guardian(s) and/or medical history and confirmed by the site investigator through non-diagnostic inspection. * Subjects suitable for nasal hygiene treatment with the study device according to its IFU. * Subjects with nasal congestion symptoms that began within 48 hours prior to enrolment. * Subjects whose legal guardian(s) signed written informed consent on their behalf to participate in the study. * Subject whose legal guardian(s) are willing and able to follow the IFU and comply with all study procedures. Exclusion Criteria (if any severe symptoms are seen in the subject, the guardian will be advised to seek medical evaluation by the subject's physician): * Subjects with known hypersensitivity or intolerance to seawater or any of its natural mineral components (e.g., sodium, chloride, magnesium) as reported by their legal guardian(s) and/or medical history. * Subjects showing severe symptoms such as persistent fever (\>38°C), severe cough, ear pain, or respiratory distress, as reported by their legal guardian(s) and/or medical history. * Subjects whose legal guardian(s) and/or medical history report any ongoing medical diagnosis or treatment for acute infection or chronic respiratory disease (e.g., asthma, pneumonia, laryngotracheobronchitis, sinusitis, etc.). * Subjects whose legal guardians(s) and/or medical history report any type of immunodeficiency. * Subjects whose legal guardian(s) and/or medical history report a neurological condition that may affect respiratory functioning. * Subjects with visible nasal injury, wounds or bleeding, or any condition that may contraindicate the use of the study device according to the device IFU. * Subjects who are currently participating or have participated in another clinical investigation within the last 30 days prior to enrolment. * Subjects using saline nasal drops or nasal sprays or pumps other than the study product within 12 hours prior to the time of enrolment or during the study. * Subjects using the study product within 24 hours prior to the time of enrolment in the study. * Subject using antibiotics, antivirals, intranasal medications, decongestants, antihistamines, mucolytics, echinacea, combination cold formulas, supplements containing ≥ 10 mg zinc that could influence symptom scores within 12 hours prior to the time of enrolment or during the study.