Overview

Polymyositis (pol-e-my-o-SY-tis) is an uncommon inflammatory disease that causes muscle weakness affecting both sides of your body. Having this condition can make it difficult to climb stairs, rise from a seated position, lift objects or reach overhead.

Polymyositis most commonly affects adults in their 30s, 40s or 50s. It's more common in blacks than in whites, and women are affected more often than men. Signs and symptoms usually develop gradually, over weeks or months.

While there is no cure for polymyositis, treatment — ranging from medications to physical therapy — can improve your muscle strength and function.

July 21, 2017
References
  1. Polymyositis and dermatomyositis. Merck Manual Professional Version. http://www.merckmanuals.com/professional/musculoskeletal-and-connective-tissue-disorders/autoimmune-rheumatic-disorders/polymyositis-and-dermatomyositis. Accessed April 13, 2017.
  2. Facts about inflammatory myopathies (myositis). Muscular Dystrophy Association. https://www.mda.org/sites/default/files/publications/Facts_Inflamm_Myopathies_P-199.pdf. Accessed April 13, 2017.
  3. Polymyositis information page. National Institute of Neurological Disorders and Stroke. https://www.ninds.nih.gov/Disorders/All-Disorders/Polymyositis-Information-Page. Accessed April 13, 2017.
  4. Goldman L, et al., eds. Inflammatory myopathies. In: Goldman-Cecil Medicine. 25th ed. Philadelphia, Pa.: Saunders Elsevier; 2016. https://www.clinicalkey.com. Accessed April 13, 2017.
  5. Daroff RB, et al. Disorders of skeletal muscle. In: Bradley's Neurology in Clinical Practice. 7th ed. Philadelphia, Pa.: Saunders Elsevier; 2016. https://www.clinicalkey.com. Accessed April 13, 2017.
  6. Miller ML, et al. Treatment of recurrent and resistant dermatomyositis and polymyositis in adults. http://www.uptodate.com/home. Accessed April 13, 2017.
  7. Miller ML, et al. Initial treatment of dermatomyositis and polymyositis in adults. http://www.uptodate.com/home. Accessed April 13, 2017.
  8. Chang-Miller A (expert opinion). Mayo Clinic, Rochester, Minn. April 23, 2017.