Is polymyalgia a form of arthritis?

Polymyalgia rheumatica (PMR) is a condition that causes widespread muscle pain and stiffness, usually around the shoulders and hips, but sometimes affecting the neck and back. It sometimes develops alongside, or after, giant cell arteritis (GCA), a rare condition that causes inflammation of the blood vessels. Some people with PMR may develop GCA, but most don’t. Symptoms start within 2 to 4 weeks, which is unusual in arthritis. PMR is not usually harmful, but if left untreated can be very uncomfortable and may result in problems with movement.

While polymyalgia rheumatica is not traditionally classified as a form of arthritis, it can sometimes be associated with inflammatory arthritis, such as rheumatoid arthritis.