Nummular headache can occur in isolation, known as primary nummular headache, or it can be associated with an underlying condition, known as secondary nummular headache. Secondary nummular headaches are less common and can be caused by various factors, including head trauma, infections, or structural abnormalities in the brain.
Some studies have also suggested that certain triggers such as stress, weather changes, and hormonal fluctuations may increase the risk of developing nummular headache.