Pantoprazole is a proton pump inhibitor (PPI) that suppresses gastric acid secretion by irreversibly blocking the hydrogen-potassium ATPase enzyme in gastric parietal cells. While not a primary treatment for cluster headache, some clinical observations suggest it may have potential off-label benefits in reducing inflammatory processes that could contribute to headache pathogenesis, though more research is needed to definitively establish its efficacy in this context.