Cluster headaches are attacks of severe pain in one side of the head, often around the eye. They begin quickly and without any warning. The attacks usually last between 15 minutes and 3 hours. They usually occur every day (often up to eight times in a day) and continue for a variable time (often between one and three months) before improving. There may then be a long period of time before the headaches come back.
This is a companion discussion topic for the original article at https://patient.info/brain-nerves/headache-leaflet/cluster-headaches