Oxygen therapy and triptans (such as sumatriptan) are primary acute treatments for cluster headache. Oxygen causes cerebral vasoconstriction and reduces intracranial blood flow, while triptans act as selective serotonin 5-HT1B/1D receptor agonists that constrict cranial blood vessels and inhibit pro-inflammatory neuropeptide release, rapidly alleviating severe pain and autonomic symptoms.