Nabumetone is a nonsteroidal anti-inflammatory drug (NSAID) that inhibits cyclooxygenase (COX) enzymes, particularly COX-2, thereby reducing prostaglandin synthesis and inflammatory pain mediators. While primarily used for rheumatoid arthritis and osteoarthritis, it has limited evidence for effectiveness in cluster headache management, with its primary action potentially providing analgesic and anti-inflammatory effects that may help modulate pain perception.