Polymyalgia rheumatica (PMR) is an inflammatory condition that causes pain and stiffness in the shoulders and the hips. The pain and stiffness is usually much worse in the mornings and fatigue is also quite common.
The cause of PMR is not well understood. Some theories propose that it might be caused by an external factor like a virus that stimulates the immune system to behave in an undesirable way.
PMR is sometimes mistaken for another type of inflammatory arthritis called rheumatoid arthritis (RA). RA can also start in the joints of the shoulders, causing pain and stiffness. RA isn’t like PMR because in RA other joints usually become affected over time, and because RA is a chronic (long-term) condition known to be an autoimmune disease. Polymyalgia rheumatica only affects the joints surrounding the shoulders and the hips.
A variety of other conditions can sometimes act like PMR, but are not related to any type of arthritis at all. These include some types of cancer, heart infections, and thyroid conditions.
In about half of people who get PMR, it’s a self-limited disease, which means it goes away by itself after a few months to a couple of years. In others, PMR can be more chronic (long-term) and can linger for much longer.
People who develop PMR are older than 50. Women are more likely to get PMR than men. PMR can also occur with another condition called Giant Cell Arteritis, which is commonly known as temporal arteritis. About 15 out of every 100 people with PMR also have temporal arteritis.