Mequitazine is primarily used as an antihistamine in the treatment of allergic conditions such as allergic rhinitis, conjunctivitis, and chronic urticaria. It helps relieve symptoms like sneezing, itching, runny nose, and watery eyes by blocking histamine H1 receptors. Due to its anticholinergic properties, it may also help reduce smooth muscle spasms and mucus secretion. Mequitazine has a long duration of action, allowing for once-daily dosing in some formulations. It is sometimes used in pediatric and adult populations, though its use may be limited by central nervous system effects such as drowsiness.