OUCH (UK) - Charity and expert patient group dedicated to helping cluster headache sufferers in the UK. Find support and membership details. Wikipedia - Cluster Headache - Excellent resource with detailed information about symptoms and treatments. ClusterHeadaches.com - Support site devoted to those who suffer from cluster headaches eMedicine - Cluster Headache - Highly technical discussion of causes and treatments for health care professionals. Cluster Headache - Consumer health resource center providing information on the causes, symptoms, and treatment. From eMedicine Health. eMedicine Health - Cluster Headache FAQs - Consumer health resource with FAQs relating to these headaches characterized by short-lived attacks of sudden, severe pain around one of the eyes. HealthCentral: Cluster Headaches - In-depth discussion with links to other resources. Cluster Busters - International organization dedicated to researching and promoting the treatment of cluster headaches with hallucinogenic substances.