Metoprolol is a selective β1-adrenergic receptor antagonist that reduces sympathetic nervous system activity and cardiac output. In cluster headache management, it may help modulate vascular tone and reduce the frequency and severity of attacks by blunting neurogenic inflammation and decreasing cerebral blood vessel reactivity. Its mechanism involves blocking beta-1 receptors in the cardiovascular system, which can potentially interrupt the pathophysiological cascades associated with cluster headache pathogenesis.