Used primarily as a long-acting, non-sedating antihistamine for the treatment of allergic conditions such as hay fever, chronic urticaria, and other allergic dermatoses. It works by selectively blocking peripheral H1 receptors, reducing symptoms like sneezing, itching, and runny nose. Due to risk of cardiac side effects, including QT prolongation and arrhythmias, its use has been discontinued or restricted in many countries. Was available in oral tablet form and was favored for its once-daily dosing and lack of central nervous system depression compared to older antihistamines.