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Lake City Medical Center



Polymyositis is a rare disease of the muscles. It usually affects the muscles closest to the trunk of the body. However, it may affect muscles anywhere in the body.

Front Muscles of Trunk
Trunk Core Muscles
Copyright © Nucleus Medical Media, Inc.


Polymyositis may be caused by a combination of genetic and environmental factors that trigger an abnormal immune response.

Risk Factors

Polymyositis is more common in women and in people aged 31-60 years old. People with a family history of systemic lupus erythematosus are also at an increased risk.


Polymyositis causes muscles become inflamed or swollen. Symptoms may include:

  • Muscle weakness
  • Muscle pain that increases over time
  • Fatigue
  • Great effort needed to climb stairs
  • Trouble rising from a chair
  • Difficulty reaching overhead
  • Chronic dry cough


You will be asked about your symptoms and medical history. A physical exam will be done.

Your bodily fluids and tissues may be tested. This can be done with:

Your muscle activity may be measured. This can be done with an electromyogram (EMG).

Images may be taken of your bodily structures. This can be done with an MRI scan.


The disease is progressive and starts slowly. If untreated, the muscles gradually become weaker. The pain in the muscles also increases. While there is no cure, treatment can improve your muscle strength and function. Talk with your doctor about the best plan for you. Options include:


Medications to treat polymyositis may include:

  • Corticosteroids to reduce inflammation
  • Topical steroids to treat skin rash
  • Immunosuppresants

IV immunoglobulin therapy is another treatment option. It involves using an IV needle to inject extra immunoglobins (special proteins) into the body. This process may help the immune system function better and reduce inflammation.

Physical Therapy

Your doctor may recommend that you work with a physical therapist to prevent permanent muscle damage. Exercise may include:

  • A regular stretching routine for weakened arms and legs
  • Light strengthening as the pain lessens and function returns

Dietary Changes

Polymyositis can lead to problems with chewing and swallowing. By working with a registered dietitian, you can learn ways to adjust to these changes and get the nutrition that you need.

Speech Therapy

Polymyositis may also cause speech problems. A speech therapist can assess your condition and create a program for you.


There are no current guidelines to prevent polymyositis.

Revision Information

  • American Autoimmune Related Diseases Association

  • The Myositis Association

  • Health Canada

  • The Arthritis Society

  • Choy EH, Hoogendijk JE, Lecky B, Winer JB, Gordon P. Immunosuppressant and immunomodulatory treatment for dermatomyositis and polymyositis. Cochrane Database Syst Rev. 2009;(4):CD003643.

  • Diagnosis. The Myositis Association website. Available at: Updated March 2015. Accessed June 26, 2015.

  • Idiopathic inflammatory myopathy. EBSCO DynaMed website. Available at: Updated May 4, 2015. Accessed June 23, 2015.

  • Myositis. American Academy of Orthopaedic Surgeons Ortho Info website. Available at: Updated July 2007. Accessed June 23, 2015.

  • Treatment. Myositis Association website. Available at: Updated March 2015. Accessed June 23, 2015.

  • Types of myositis. Myositis Association website. Available at: Updated January 2015. Accessed June 23, 2015.

  • NINDS Polymyositis information page. National Institute of Neurological Disorders and Stroke website. Available at: Updated February 23, 2015. Accessed June 23, 2015.

  • Simply stated: the creatine kinase test. Quest. 2000;7(1).

  • 11/9/2015 DynaMed's Systematic Literature Surveillance Kuo CF, Grainge MJ, Valdes AM, et al. Familial aggregation of systemic lupus erythematosus and coaggregation of autoimmune diseases in affected families. JAMA Intern Med. 2015;175(9):1518-1526.