Cluster headaches are a string of short but especially painful headaches occurring daily over a period of weeks of months. They are often seasonal and may be more severe than a migraine, though shorter in length - usually between 30 and 90 minutes. The cause of cluster headaches is not yet known. 

These headaches come on fast and may reach their most painful within five or ten minutes. They are almost on one side of the head and are characterized by a burning, piercing, or throbbing sensation. People with a cluster headache may feel their blood pulsing and feel the pain behind or around one eye. 

Warning signs of an oncoming cluster headache include a swollen or drooping eye; a smaller pupil; red or watering eyes; nasal congestion or a runny nose; and a warm and red face.  

Cluster headaches may be treated with pain or migraine medication, and by breathing oxygen through a face mask. Commonly prescribed drug classes for treating cluster headaches include ergot alkaloids, other anti-migraine drug combinations, other anti-migraine drugs, systemic corticosteroids, plain, and anti-arrhythmics, class IV.