Giant cell arteritis (GCA), or temporal arteritis, is an inflammation of the blood vessels that carry blood up through the neck to the head (carotid arteries) and those that carry blood within the head, especially those in the side of the face near the temple. This condition can cause irreversible blindness if not treated promptly.

Giant cell arteritis is the result of the body's immune system reacting against itself, known as an autoimmune response. It mostly affects people older than age 50. Giant cell arteritis causes a headache that begins as a dull, throbbing pain on one side of the head around the eye or near the temple. Occasionally the pain may feel like a stabbing or burning sensation. It may also cause jaw pain and loss of vision or blindness.

A large number of people with giant cell arteritis also have a condition called polymyalgia rheumatica (PMR), which causes muscle pain and morning stiffness—most commonly in the shoulders and pelvic area—along with fever, weight loss, and a general feeling of being unwell.

Giant cell arteritis is usually treated with corticosteroid medicine. This disease usually responds to treatment, with symptoms decreasing within 2 to 7 days. Medicine may be needed for 1 to 2 years or more to prevent symptoms from returning.