In medicine a headache or cephalalgia is a symptom of a number of different conditions of the head and sometimes neck. Some of the causes are benign while others are medical emergencies. It ranks among the most common pain complaints.^{[citation needed]}

There are a number of different classification systems for headaches. The most well-recognized is that of the International Headache Society.

Treatment of a headache depends on the underlying etiology or cause.  Chiropractic is one alternative to the treatment of such a condition.

           Headache is a common symptom in patients suffering from neck disorders. The percentage of headaches in association with degenerative changes of the cervical spine ranges from 13 to 79% and that in association with indirect trauma of the cervical spine from 48 to 82%. Based on neuroanatomical and neurophysiological studies, the relationship of the upper cervical spine and the trigeminal nuclei has been demonstrated and serves as an explanation for perceived head pain in cervical spine disorders. As a source of pain, tension in the suboccipital muscles, irritation of the third occipital nerve, and degenerative changes of the C2/C3 joints have been discussed. Bogduk, in his studies, asserts a direct causative role of mechanical derangement of the cervical spine in the pathogenesis of cervicogenic headaches.

Ther Umsch 1997 (Feb);   54 (2):   94–97