Confirmatory Study on the Efficacy and Safety of the Fixed-dose Combination of Desloratadine/Betamethasone Versus Desloratadine

Inclusion Criteria: * Willing to participate in the study and able to provide written informed consent. * Clinical diagnosis (based on medical history and physical examination) of active allergic rhinitis at study entry. * Patients presenting with moderate to severe nasal symptoms, with a Total Nasal Symptom Score (TNSS) ≥5. * In the case of women of childbearing potential who are sexually active, the use of an acceptable contraceptive method (barrier and/or hormonal), as determined by the investigator. * In the opinion of the Principal Investigator or treating physician, the patient is indicated for treatment with the investigational product and may derive clinical benefit from it. Exclusion Criteria: * Patients for whom the investigational drug is medically contraindicated. * Known allergy or hypersensitivity to the active ingredient, study medications, related products, or excipients. * History of nasal trauma (surgical or accidental) within the past week. * Positive pregnancy test, pregnant or breastfeeding women, or women planning to become pregnant during the course of the study. * Acute or chronic lower or upper respiratory tract infections, such as the common cold, influenza, pneumonia, bronchitis, or chronic sinusitis. * History of non-allergic rhinitis, such as chronic non-allergic rhinitis, drug-induced rhinitis, atrophic rhinitis, hormonal rhinitis, or unilateral rhinitis, as reported in the medical history or patient interview. * History of nasal polyposis, primary ciliary dyskinesia syndrome, and/or non-allergic rhinitis with eosinophilia syndrome (NARES). * Current smokers, or history of alcohol and/or drug abuse in the past year according to DSM-V criteria. * History of seizure disorders, status epilepticus, or generalized tonic-clonic seizures. * History of chronic hepatic failure classified as Child-Pugh C, as reported in the medical history or patient interview. * History of chronic renal failure (glomerular filtration rate \< 30 mL/min/1.73 m²), as reported in the medical history or patient interview. * Any condition, in the investigator's opinion, that affects prognosis or precludes outpatient management, which must be evaluated by the principal investigator to determine the subject's eligibility. * History of severe, progressive, unstable, or advanced disease of any kind that could interfere with efficacy and safety evaluations or pose a risk to the patient. * Oncology patients (except those with basal cell skin cancer) or patients with serious illnesses who, in the investigator's opinion, have a poor prognosis or life expectancy of less than one year, including those with mental health disorders. * Active participation in another clinical trial involving an investigational treatment or participation in any clinical study within the previous two weeks. * Patients whose participation in the study may be influenced (e.g., employees of the research center or sponsor, incarcerated individuals, etc.). * Patients with symptoms suggestive of active COVID-19 infection (e.g., fever, cough, dyspnea) and/or contact within the past 14 days with a suspected or confirmed COVID-19 case and/or a positive COVID-19 test.