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from the American Academy of Orthopaedic Surgeons

Diseases & Conditions



Staying Healthy


Myositis is a rare disease in which the immune system chronically inflames (produces inflammation in) the body's own healthy muscle tissue. Over time, this persistent inflammation weakens muscles, often resulting in muscle aches, pain, and fatigue.

There are several types of myositis. It usually develops slowly over time with symptoms that range in severity from mild to disabling. It can affect both children and adults.

It is not known what triggers the immune system's attack. There is no cure for myositis; however, prompt treatment for some types of myositis may prevent the disease from worsening.


  • Muscle weakness. Weakness and pain in the muscles of the hips and shoulders is often a first sign of myositis. You may have difficulty getting up from a chair, combing your hair, or climbing stairs. You may become too tired to walk or stand.
  • Difficulty swallowing or breathing. Myositis can affect the muscles in the front of the neck and throat, making it hard to speak or swallow (dysphagia). When it affects the lungs or chest muscles, you may have trouble breathing.
  • Skin changes. People with a certain form of myositis may also develop a rash on the face, knuckles, and other parts of the body.
  • Other. Other possible symptoms include fever, and joint pain and swelling.

Types of Myositis


Polymyositis inflames and weakens muscles in many parts of the body, especially those closest to the trunk. Common symptoms of polymyositis include:

  • Dysphagia (trouble swallowing)
  • Fatigue
  • Pain in the joints and muscles


Dermatomyositis inflammation damages both muscle fibers and skin.

  • As with polymyositis, you will experience muscle weakness, pain, and fatigue.
  • In addition, you will have a distinctive patchy, reddish rash on the eyelids, cheeks, bridge of the nose, back or upper chest, elbows, knees ,and knuckles.
  • In some cases, you may develop hardened bumps under the skin.
  • A small number of people also develop lung problems.

People with inflammatory myopathies, especially adults with a variant of dermatomyositis, can have an increased risk of cancer. This risk increases with age and is associated with the same common cancers that affect the general population, including cancer of the lung, breast, prostate (in men), and ovaries (in women).

In most cases, people newly diagnosed with polymyositis or dermatomyositis should be screened for cancer. Depending on the person’s age and sex, screening may include one or more of the following:

  • Blood tests
  • Chest X-ray
  • Colonoscopy
  • Mammogram
  • Pap test
  • Transvaginal ultrasound

Inclusion-body Myositis

Symptoms of inclusion-body myositis typically begin after age 50 with very gradual weakening of muscles throughout the body.

  • Weakening of grip strength may be an initial complaint.
  • You may develop dysphagia (trouble swallowing),
  • You may have atrophy (wasting, or weakening) of the forearms and/or thigh muscles.

Unlike other forms of myositis, inclusion-body myositis occurs more often in men than in women. There are currently no effective treatments known for inclusion-body myositis.

Juvenile Myositis

The most common form of myositis that affects children is dermatomyositis, a difficult-to-treat condition with symptoms that may include:

  • Muscle weakness
  • Skin rash
  • Dysphagia (trouble swallowing)
  • Calcinosis (hardened bumps under the skin)

Less commonly, children may develop juvenile forms of polymyositis and inclusion-body myositis.

Doctor Examination

Myositis can be challenging to diagnose. Symptoms vary from person to person, and your doctor must rule out other conditions that affect muscles, such as:

  • Hypothyroidism
  • Toxin exposure
  • Drug reactions
  • Genetic disorders

Be sure to give your doctor your complete medical history, and fully describe your symptoms and when they began.


  • Laboratory tests. Your physical examination will probably include one or more blood tests to look for autoantibodies and muscle enzymes such as creatine kinase (CK).
  • Electromyogram. You may also need other specialized tests, such as an electromyogram (EMG), which measures the electrical activity of the muscles.
  • Biopsy. Your doctor may request a muscle biopsy, in which a small piece of muscle is removed and examined under a microscope to show whether/how muscle fibers are damaged. Muscle biopsy can help provide a specific diagnosis.
  • Imaging. In some cases, doctors use magnetic resonance imaging (MRI) to identify areas where muscle is inflamed.


Although there is no cure for myositis, prompt and aggressive treatment to reduce inflammation of polymyositis and dermatomyositis can help prevent muscle weakness from progressing (getting worse over time) and might help restore some of your strength.

  • Medications. Corticosteroids, such as prednisone, and other drugs that suppress the immune system (immunosuppressants) may slow down the attack on healthy tissue and improve skin rash. Your doctor will probably repeat blood tests throughout your treatment for myositis to monitor improvement. 
  • Exercise. After drug treatment takes effect, a program of regular stretching exercises prescribed by your doctor can help maintain range of motion in weakened arms and legs. Physical therapy may also help prevent permanent muscle shortening. Engaging in physical activity that matches your ability can help improve your mobility and quality of life. Talk to your doctor or physical therapist about an exercise program that will help you to continue your daily activities.
  • Rest. Getting enough rest is an important part of managing myositis. Symptoms may worsen when you are fatigued. Try to get a full night's sleep and take short breaks during the day when you need to. You may also want to add whirlpool baths, heat, and gentle massage to your relaxation regimen.
  • Aspiration prevention. Patients who have trouble swallowing must take care to avoid inhaling (aspirating) foods and liquids — in other words, keeping foods and liquids from "going down the wrong pipe" into the lungs. This may be done by:
    • Elevating the head of the bed while eating or drinking
    • Adding thickening agents to drinks
    • In severe cases, having a feeding tube placed in the stomach

Last Reviewed

December 2023

Contributed and/or Updated by

Yamini Mennon, MD

Peer-Reviewed by

Thomas Ward Throckmorton, MD, FAAOS

AAOS does not endorse any treatments, procedures, products, or physicians referenced herein. This information is provided as an educational service and is not intended to serve as medical advice. Anyone seeking specific orthopaedic advice or assistance should consult his or her orthopaedic surgeon, or locate one in your area through the AAOS Find an Orthopaedist program on this website.