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  • Cynthia M. Johnson, MA
Publication Type:




Polymyositis is a rare disease of the muscles. They become inflamed or swollen. This can lead to severe movement problems.

Front Muscles of Trunk.

Trunk Core Muscleshttp://services.epnet.com/getimage.aspx?imageiid=76457645si55551606.jpgsi55551606.jpgNULLjpgsi55551606.jpgNULL\\hgfiler01a\intellect\images\si55551606.jpgNULL87NULL2008-12-10343400Copyright © Nucleus Medical Media, Inc.


Polymyositis may be caused by changes in genes. The changes may cause the immune system to attack muscles.

Risk Factors

Polymyositis is more common in women and people who are 30 to 50 years of age.

The risk of this problem is higher in people who have family members with lupus.


The muscles near the trunk of the body are most affected. A person with polymyositis may have:

  • Poor muscle strength in the hips, neck, and shoulders
  • Muscle pain that gets worse over time
  • Low energy
  • To use more effort than usual to climb stairs
  • Trouble rising from a chair
  • Problems reaching above the head
  • A dry cough that will not go away
  • Problems swallowing

Polymyositis can lead to:


The doctor will ask about symptoms and health history. A physical exam will be done.

These tests may be done to confirm polymyositis:

  • Blood tests—to look for signs of muscle breakdown
  • Electromyogram (EMG)—test electrical activity of the muscle
  • MRI scan—to look for swelling
  • Muscle biopsy—to look for swelling or damage


The goal of treatment is to manage symptoms. There is no cure. Polymyositis starts slowly and gets worse over time. The muscles will get weaker and more painful without treatment.

The doctor may advise:


Polymyositis cannot be prevented.


Some options are:

  • Corticosteroids—to ease swelling
  • Immunosuppressants—to decrease damage caused by immune system
  • IV immunoglobulin therapy—special proteins that may help the immune system work better

Support Therapy

Muscle weakness can make it hard to move. Therapy may help. Options are:

  • Physical therapy to help with strength and range of motion
  • Occupational therapy to help with daily tasks and self care
  • Speech therapy to help with swallowing and speech




  • Diagnosis. The Myositis Association website. Available at: https://www.myositis.org/about-myositis/diagnosis.
  • Idiopathic inflammatory myopathy. EBSCO DynaMed website. Available at: https://www.dynamed.com/condition/idiopathic-inflammatory-myopathy.
  • Milone, M. Diagnosis and Management of Immune-Mediated Myopathies. Mayo Clin Proc, 2017; 92(5): 826-837.
  • Myositis. Ortho Info—American Academy of Orthopaedic Surgeons website. Available at: https://orthoinfo.aaos.org/en/diseases--conditions/myositis.
  • Polymyositis. National Institute of Neurological Disorders and Stroke website. Available at: https://www.ninds.nih.gov/health-information/disorders/polymyositis.
  • Treatment and disease management. Myositis Association website. Available at: http://www.myositis.org/about-myositis/treatment-disease-management.
  • Types of myositis. Myositis Association website. Available at: https://www.myositis.org/about-myositis/types-of-myositis.


  • Rimas Lukas, MD
Last Updated:

This content is reviewed regularly and is updated when new and relevant evidence is made available. This information is neither intended nor implied to be a substitute for professional medical advice. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with questions regarding a medical condition.