Myositis

Myositis is a rare group of diseases that cause inflammation and weakness in the muscles. It can make everyday movements like walking, lifting objects, or climbing stairs difficult. Some types of myositis can also affect other parts of the body, including the skin, lungs, and heart. Common symptoms include muscle pain, fatigue, and swelling. Myositis can be caused by autoimmune reactions, infections, or certain medications. Examples of types of myositis include polymyositis (causes muscle weakness, typically affecting muscles closest to the trunk, such as those in the hips, thighs, shoulders, and upper arms) and dermatomyositis (similar to polymyositis but also causes a distinctive skin rash, which may appear on the face, knuckles, chest, and back).