Myositis

What is myositis?

Myositis is the inflammation or swelling of the muscles. There are two primary kinds of myositis:

• Polymyositis, which causes muscle weakness, usually in the muscles closest to the trunk of the body
• Dermatomyositis, which causes muscle weakness, plus a skin rash

What are the symptoms of myositis?

The following are symptoms that are characteristic of myositis:

• Trouble rising from a chair
• Difficulty climbing stairs or lifting arms
• Tiredness after standing or walking
• Trouble swallowing or breathing
• Muscle pain and soreness that does not resolve after a few weeks
• Known elevations in muscle enzymes by blood tests

What causes myositis?

The exact cause of myositis is unknown, but it shares many characteristics with autoimmune disorders, in which the immune system mistakenly attacks its own body tissues.

How is myositis diagnosed?

Doctors may use a physical exam, lab tests, and/or imaging tests to help diagnose myositis. In addition, a muscle biopsy may confirm a diagnosis.

What are the available treatments for myositis?

To date, there is no cure for myositis, but treatment options exist to improve muscle strength and function for each specific type. See our pages on these types (linked above) for more specific information.

Where can I find out more about myositis?

• Medline Plus
• The Myositis Association
• Johns Hopkins Medicine