Antazoline is a first-generation antihistamine commonly used in ophthalmic preparations to treat allergic conjunctivitis. It works by blocking histamine H1 receptors, which helps reduce symptoms such as redness, itching, tearing, and swelling of the eyes caused by allergic reactions. It is often combined with other agents like naphazoline (a vasoconstrictor) or zinc sulfate, providing both antihistaminic and mild decongestant effects to alleviate eye redness and irritation. Due to its local action and rapid onset, it is effective for short-term relief of ocular allergy symptoms and is a frequent ingredient in over-the-counter eye drops.