Inclusion Criteria:  Age ≥ 6 years and < 12 years. Diagnosis of moderate to severe persistent allergic rhinitis (PAR) according to ARIA (Allergic Rhinitis and Its Impact on Asthma) criteria (Annex 1). Sensitization to aeroallergens confirmed by the presence of a positive result on the immediate skin test (PRICK test) and/or by the presence of specific IgE on the radioallergoabsorbent test (RAST) . Total nasal symptom score (TNSS ) ≥ 8 points (Annex 2). Symptom intensity score "nasal obstruction" ≥ 2 points. Correct use of optimized treatment for PER, including use of intranasal corticosteroids, as assessed by the investigator. Signing of the Informed Consent Form (ICF) and the Informed Assent Form (IAF) before performing any study procedure.  Exclusion Criteria:  Being using or having an indication for antibiotic therapy upon selection for the study. Use of prednisolone or other oral corticosteroids in the last seven (07) days. Asthma diagnosis. Covid-19 diagnosis within four (04) weeks prior to randomization. Positive for SARS-COV-2 rapid antigen test at the time of randomization. Known allergy to desloratadine, prednisolone or any component of the product formulations under investigation. Presence of systemic fungal infections or uncontrolled infections. Presence of any serious or uncontrolled diseases, at the investigator's discretion. Presence of pregnancy or lactation. Women of childbearing age who do not agree to use a contraceptive method known to be effective, unless surgically sterile or who expressly declare themselves exempt from the risk of pregnancy for not engaging in sexual practices or exercising them in a non-reproductive manner. Participation in a clinical research protocol in the last 12 months, unless, at the investigator's discretion, their participation in the study may incur a direct benefit to the participant. Presence of any condition that, at the investigator's discretion, renders the patient unfit to participate in the study.