Cluster Headache is rare, but is characterized by extremely severe headache attacks that, strictly unilaterally, are usually localized in or around the eye. Sufferers compare the pain to a knife or a red-hot poker. The attacks last from 15 to 180 minutes and are accompanied by typical accompanying symptoms. These include redness or tearing of the eye, a stuffy or runny nose, swelling of the eyelids, or sweating of the face, always on one side, on the side of the pain. During the attack, sufferers cannot lie down, but are agitated and restless. Acute cluster headaches are treated with oxygen or medication, which sufferers can inject themselves or administer in the form of a nasal spray. Due to the frequent occurrence of the attacks and their often unbearable intensity, preventive treatment with certain medications is usually necessary. Further information can be found in the Download section.