Flonase (fluticasone propionate) nasal spray is used once per day in both adults and children to provide 24-hour relief from allergy symptoms such as sneezing, runny nose, nasal congestion, and itchy, watery eyes. Nasal steroids like Flonase are most effective when used on a regular basis. It may take 3 to 4 days of regular use for the full effect during allergy season.