<p>Olopatadine, an antihistamine, works by blocking the action of histamine in the body, which reduces allergy symptoms. Olopatadine Hydrochloride treats sneezing, itching, runny nose, and other nasal symptoms of allergies. Olopatadine Nasal Spray contains 0.6% w/v Olopatadine (base) in a nonsterile aqueous solution with pH of approximately 3.7. After initial priming (5 sprays), each metered spray from the nasal applicator delivers 100 microliters of the aqueous solution containing 665 mcg of olopatadine Hydrochloride, which is equivalent to 600 mcg of Olopatadine (base). Olopatadine Nasal Spray also contains benzalkonium chloride (0.01%), dibasic sodium phosphate, edetate disodium, sodium chloride, hydrochloric acid and/or sodium hydroxide (to adjust pH), and purified water.</p>