**Study Overview**: This study tests a nasal spray medication, called monometasone furoate, to see if it works as well and is as safe as a similar spray for people with **seasonal allergic rhinitis**. Seasonal allergic rhinitis is when your nose feels stuffy, itchy, or runny at certain times of the year, like when flowers bloom or leaves fall. People in the study will not know if they are using the test spray or the other spray, as the trial is *double-blind*. **Key Points**: - **Study Duration**: Participants will need to visit the study site multiple times and follow the study plan carefully. - **Eligibility**: Must be 18-65 years old, have moderate to severe seasonal allergy symptoms, and not be pregnant or breastfeeding. - **Safety and Risks**: Participants must not have certain health issues, like severe liver problems or asthma needing long-term treatment, and should not be allergic to the test spray. If you are interested in joining, you will need to sign a form showing that you understand the study. Always make sure you feel comfortable with the study rules and visits before agreeing to participate.