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 and sedative properties, it may also be used in managing certain symptoms of motion sickness and vertigo. Mequitazine has a long duration of action, allowing for less frequent dosing, which improves patient compliance in chronic allergy management.