Quinotolast sodium is primarily used as an antiallergic agent, particularly in the treatment of allergic conjunctivitis. It works by stabilizing mast cells, which prevents the release of histamine and other inflammatory mediators that cause allergic symptoms. This makes it effective in reducing redness, itching, and swelling in the eyes associated with allergic reactions. It is often formulated as an ophthalmic solution for direct application to the eyes, providing quick relief from discomfort. Additionally, its anti-inflammatory properties make it useful in managing other allergic conditions where mast cell stabilization is beneficial.