Tramadol is a centrally-acting synthetic opioid analgesic that acts as a weak μ-opioid receptor agonist and inhibits serotonin and norepinephrine reuptake, providing pain relief through multiple mechanisms. In cluster headache treatment, it modulates pain perception and may offer some relief, though it is not considered a first-line therapy for this condition. Its mixed mechanism of action can potentially interrupt pain signaling and provide moderate analgesic effects.