Dermatomyositis and Polymyositis

Dermatomyositis (DM) and polymyositis (PM) are rare conditions. They are thought to be caused by an overactive immune system attacking normal, healthy tissue. They can cause inflammation, swelling, and other problems.

About dermatomyositis

Dermatomyositis causes weakness in the skeletal muscles—thighs, torso, shoulders, hips, and upper arms. It also causes a distinctive rash around the eyes and skin of the joint areas.

Learn More

About polymyositis

Polymyositis causes weakness in the skeletal muscles—thighs, torso, shoulders, hips, and upper arms—but does not usually cause a rash, as dermatomyositis does.

Learn More