Hemicrania continua headaches affect either the right or the left side of the head, but not both, and chronic migraine headaches affect either just one side of the head or both, according to Mayo Clinic. These are both types of long-lasting chronic headaches that generally last more than four hours.
Chronic migraine headaches are common in people who have a history of episodic migraines. A chronic migraine strikes at least eight days in a month for a minimum of three months. In addition to sometimes affecting the right side of the head, these headaches present with a throbbing sensation, are triggered or worsened by routine physical activities, and lead to at least moderate pain. They also cause either sensitivity to sound and light or vomiting and/or nausea, as stated by Mayo Clinic.
In addition to affecting only one side of the head, hemicrania continua happen daily without allowing any pain-free times of the day. They usually stay at a moderate level of discomfort but periodically spike to severe levels. Sometimes these headaches worsen and develop symptoms similar to migraines, and they respond to indomethacin. Patients with hemicrania continua also have at least one of these symptoms: a feeling of restlessness, narrowing pupils, droopy eyelids, nasal congestion or redness, and tearing of the eye on the same side as the pain, reports Mayo Clinic.