What does the study include?
* For adults: The study is divided into 4 periods and will last about 8 months.
* For adolescents: The study includes 5 periods and will last about 1 year and 4 months.
* All participants will receive either the investigational medicine or a placebo. This clinical research will evaluate whether the investigational treatment is safe and effective in reducing symptoms of nasal allergies.
* In addition, everyone in the study will receive background therapy, which includes a nasal spray provided by the study team.
If you are currently taking other allergy medications, you may be able to continue them during the study or switch to a different version, as explained by the study team.