Polymyositis: Symptoms & Signs

Medically Reviewed on 8/11/2020

Polymyositis is a disease of muscle that is characterized by inflammation of the muscle fibers, with white blood cells invading the muscle fibers. The muscles affected are typically those closest to the trunk or torso, and it affects both sides of the body. Polymyositis affects people of all ages and is slightly more common in females than in males.

Signs and symptoms of polymyositis include

  • progressive muscle weakness with periods of increased symptoms, referred to as flares or relapses, and
  • periods of minimal or no symptoms, known as remissions.

Other associated symptoms and signs can include

Cause of polymyositis

The cause of polymyositis is not known.

Other polymyositis symptoms and signs

  • Atrophy (Shrinking) of Muscles
  • Difficulty Walking
  • Fatigue
  • Loss of Strength
  • Low-Grade Fever
  • Muscle Pain and Stiffness
  • Periods of Minimal or No Symptoms, Known as Remissions
  • Progressive Muscle Weakness With Periods of Increased Symptoms, Referred to as Flares or Relapses
  • Trouble Swallowing
  • Weight Loss


The term arthritis refers to stiffness in the joints. See Answer

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Jameson, J. Larry, et al. Harrison's Principles of Internal Medicine, 20th Ed. New York: McGraw-Hill Education, 2018.