Fexofenadine is a second-generation, long lasting H1-receptor antagonist which has a selective and peripheral H1-antagonistic action. Fexofenadine blocks the H1-receptor and thus prevents activation of cells by histamine in the GI tract, large blood vessels and bronchial smooth muscle. This leads to relief of the allergic symptoms. Unlike most other antihistamines, Fexofenadine does not enter the brain from the blood and therefore, does not cause drowsiness. Fexofenadine lacks the cardiotoxic potential, since it does not block the potassium channel involved in repolarization of cardiac cells.