Proton pump inhibitors (PPIs) are primarily used to reduce gastric acid secretion by irreversibly blocking the hydrogen/potassium ATP enzyme in gastric parietal cells. In the context of Cluster Headache, some research suggests PPIs may have a potential off-label neuroprotective and anti-inflammatory effect, potentially modulating neurogenic inflammation and providing symptomatic relief, though their precise mechanism in headache management is not fully established.