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Dermatomyositis is an inflammatory condition that causes muscle inflammation, progressive weakness and skin rashes. Some individuals also experience problems with the heart and lungs. Dermatomyositis is part of a larger group of inflammatory muscle conditions (inflammatory myopathies) that includes polymyositis. While people of any age can be affected, dermatomyositis most often affects adults ages 40 to 60. Women are twice as likely to be diagnosed with the condition, and in the U.S, Black women have been found to be particularly susceptible. The exact cause of dermatomyositis is unknown. Currently, no targeted treatment for dermatomyositis exists.


  • muscle weakness, stiffness or soreness
  • a purple-red skin rash, often painful and/or itchy, most often found on the eyelids, cheeks, nose, back, upper chest, elbows, knees and knuckles
  • problems swallowing and/or breathing
  • fatigue


It’s unknown exactly what causes dermatomyositis, though it is thought to result from a problem with an immune response to the body’s own tissues. Genetic, immune and environmental factors may all play a role in a person’s risk for developing dermatomyositis. 

How dermatomyositis is diagnosed 

Diagnosis of dermatomyositis begins with a physical exam showing characteristic patterns of muscle weakness and skin symptoms. Blood tests can indicate signs of inflammatory muscle disease. Electromyography (EMG), magnetic resonance imaging (MRI) and muscle or skin biopsies may also help to establish the diagnosis.

Existing treatment

There is currently no targeted treatment for dermatomyositis. Individuals with dermatomyositis are often treated with steroid hormones called glucocorticoids. Some patients are treated with drugs that suppress overactive immune systems. Skin rashes may be treated with topical steroids, various other drugs and sun avoidance. Patients may also receive physical therapy to address muscle weakness.


Dermatomyositis is estimated to occur in approximately 9.63 individuals per million worldwide. Approximately 3 per million children are affected by juvenile dermatomyositis.

Related conditions

  • amyopathic dermatomyositis
  • polymyositis
  • scleroderma
  • systemic lupus erythematosus (SLE)

Community resources

The latest on our research

We are jumpstarting our dermatomyositis program in partnership with Myositis Support and Understanding to accelerate research on this condition and to ultimately improve treatment options. We welcome all patients and caregivers interested in participating and spreading the word to the dermatomyositis community.

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