First line treatment is aimed at reducing symptoms while minimizing risk of side effects from treatment. Nasal saline and nasal or oral antihistamines are reasonable first choices. Intranasal steroids carry the risk of sides effects from systemic absorption (adrenal suppression, effects on bone growth, hyperglycemia), and safety of sublingual immunotherapy has not been established for children under age 10 (for grasses) or under age 18 (for ragweed).
Agency for Health Care Research and Quality (AHRQ). Treatments for seasonal allergic rhinitis. Accessed February 7, 2015 and available at: http://effectivehealthcare.ahrq.gov/search-for-guides-reviews-and-reports/?pageaction=displayproduct&productid=1587
Glacy J, Putnam K, Godfrey S, et al. Treatments for Seasonal Allergic Rhinitis; Comparative Effectiveness Reviews, No. 120, Rockville (MD): Agency for Healthcare Research and Quality (US); 2013 Jul.