Cluster headaches are recurring headaches that occur in groups or
cycles. The headaches appear suddenly and cause severe, debilitating pain on
one side of the head, along with a watery eye and nasal congestion on the
affected side of the head.
The cause of cluster headaches is unknown. Although there is no
cure for cluster headaches, medicines can reduce the frequency and duration
of the painful headaches.
Anne C. Poinier, MD - Internal Medicine & Colin Chalk, MD, CM, FRCPC - Neurology