Various conditions with the symptom of HEADACHE. Headache disorders are classified into major groups, such as PRIMARY HEADACHE DISORDERS (based on characteristics of their headache symptoms) and SECONDARY HEADACHE DISORDERS (based on their etiologies). (International Classification of Headache Disorders, 2nd ed. Cephalalgia 2004: suppl 1)

Synonyms: Chronic Headache, Headache, Intractable, Headache, Chronic, Headaches, Chronic, Chronic Headaches, Headaches, Intractable, Chronic Daily Headaches, Cephalgia Syndrome, Headaches, Chronic Daily, Headache Disorder, Intractable Headaches, Chronic Daily Headache, Syndrome, Headache, Headache Syndrome, Intractable Headache, Headache Disorders, Daily Headaches, Chronic, Headache Syndromes, Daily Headache, Chronic, Cephalgia Syndromes, Headache, Chronic Daily