Study to evaluate the two different strengths and dose regimen of GSP 301 to be effective in treatment of seasonal allergic rhinitis.

Key Inclusion Criteria:

1. Aged ≥12 years and older inclusive of either sex.
2. Documented clinical history of SAR (for at least 2 years preceding the Screening Visit [Visit 1]) with exacerbations (clinical evidence of active symptoms) during the study season for the mountain cedar pollen
3. A 12-hour reflective TNSS ≥ 8 out of a possible 12 and a congestion score of ≥ 2 for the AM assessment at the Screening Visit (Visit 1).

Key Exclusion Criteria:

1. Pregnant or lactating women.
2. Plans to travel outside the known pollen area for the investigative site for > 24 hours during the last 7 days of run in period.
3. History of nasal polyps of other clinically significant respiratory tract malformations, recent nasal biopsy, nasal trauma (such as nasal piercing) or surgery, atopic dermatitis or rhinitis medicamentosa.
4. History of anaphylaxis and/or other severe local reaction(s) to skin testing.
5. History of positive test for HIV, Hepatitis B or Hepatitis C infection.
6. Documented evidence of acute or significant chronic sinusitis or chronic purulent postnasal drip.
7. Subjects with an active pulmonary disorder or infection.
8. Subjects with posterior subcapsular cataracts or glaucoma.