What Is It?
Myositis is the medical term for muscle inflammation. In myositis, inflammation damages the fibers of a muscle. This causes muscles to be weak by interfering with the ability of the muscles to contract. Although myositis can cause muscle aches and muscle tenderness, weakness is usually the dominant symptom.
In some cases, myositis is a short-term problem that goes away after a few days or weeks. In other cases, it is part of a chronic (long-term) condition. Chronic forms of myositis can lead to muscle atrophy (wasting and shrinking) and severe disability.