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Myositis Causes, Symptoms, and Treatments

The definition of myositis is inflammation of the muscles. This happens when the immune system attacks the muscles by mistake.

Myositis can affect how you walk, move your arms and hands, swallow, and breathe.

Treatments help to prevent muscle loss and heart, lung, and other problems myositis can cause.

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What Is Myositis?

Doctors define myositis as a rare autoimmune disease. The immune system becomes overactive and attacks the body's muscle tissue.

When the body sends immune cells to the muscles, this causes inflammation. Over time, the muscles get weak.

Myositis can cause problems in muscle groups and other symptoms throughout the body. This includes muscles in the arms and legs as well as the muscles that help you swallow. Myositis can also attack the heart and lungs, causing shortness of breath.

Myositis can cause skin issues, too.

Is myositis a serious illness?

Yes. Myositis can cause health problems that can lead to death without proper treatment.

For instance, if myositis affects the:

  • Lungs, it can be hard to breathe.
  • Heart, it can lead to coronary artery disease, heart rhythm problems, and even heart failure.

What Are the Different Types of Myositis?

There are four types:

  • Dermatomyositis affects muscles mainly in the arms, legs, and trunk, as well as those that help you swallow. But it also causes skin rashes, mostly on the face, torso, knuckles, elbows, or knees.
  • Polymyositis affects the same muscle groups dermatomyositis does. It also causes the same skin rashes that patients with dermatomyositis have.
  • Necrotizing myopathy is a more newly defined form of myositis with muscle weakness similar to that of dermatomyositis and polymyositis. It shows different features on a muscle biopsy than dermatomyositis and polymyositis do.
  • Inclusion body myositis is more common in older people. Symptoms start more slowly than they do for other types of myositis. It doesn't respond well to treatment and often leads to disability over time. It can more commonly affect muscles in the hands, impacting grip strength and weakening the arms and legs.
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What Causes Myositis?

Doctors think that some people are prone to getting myositis through genetics. A bacteria, virus, or chemical may then trigger the disease.

But many people don't know what triggers their myositis.

What Are the Risk Factors of Myositis?

There are risk factors that increase the odds of getting myositis:

  • Age. Myositis can start at any age, but inclusion body myositis is more common after age 50.
  • Gender. Women are more likely to get myositis. But inclusion body myositis is more common in men.
  • Other autoimmune diseases. Having one autoimmune disease may put you at a higher risk of other ones, such as thyroid problems.
  • Statins. In very rare cases, statins — drugs that lower cholesterol — can trigger necrotizing myopathy.
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What Are the Symptoms and Complications of Myositis?

Myositis symptoms and complications vary by type and severity. They may come on all of a sudden or slowly get worse over time.

Many people have symptoms that improve or go away only to come back or get worse.

Myositis symptoms and complications include:

  • A rash on your face, knuckles, or elsewhere on the body.
  • Aspiration pneumonia from food or liquid going into the lungs if it affects the swallowing muscles.
  • Breathing problems (if it's attacking the lung tissue).
  • Falling or tripping.
  • Feeling tired after you walk or stand.
  • Heart issues, such as an arrhythmia (irregular heartbeat) or heart failure.
  • Permanent muscle damage leading to irreversible weakness.
  • Scarring of the lungs.
  • Swallowing problems.
  • Trouble climbing stairs.
  • Trouble standing from sitting or sitting from lying down.
  • Weakness that makes it hard to lift your arms.
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How Do You Diagnose Myositis?

A myositis diagnosis often involves a physical exam and tests.

Your doctor will ask you about your symptoms and when they started.

They'll need to rule out other problems that could cause your symptoms, like infections or muscular dystrophy. So, doctors often test for myositis along with other health issues.

There's no single test to confirm myositis. Instead, doctors base the diagnosis on the results of many tests and your pattern of symptoms.

Tests to help diagnose myositis

Your doctor may order:

  • Blood tests to look for elevated creatine kinase levels, signaling inflammation in the muscle tissue in people with myositis.
  • An electromyogram (EMG) to measure electrical signals in the muscles.
  • A biopsy to remove a small piece of muscle tissue to send to a lab for testing.
  • An MRI to look for inflammation in your muscles.
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What Are the Treatment Options for Myositis?

Doctors treat myositis with medicine, physical therapy (PT), and lifestyle changes.


Your doctor may prescribe one or more of the following medicines. They'll choose drugs that can treat your issue with the least side effects.

Treatment options include:

  • Glucocorticoids (such as steroids) to reduce inflammation.
  • Immune-suppressing drugs to keep your immune system from attacking healthy tissue.
  • Biologic (injectable) drugs to alter certain immune system processes.
  • Intravenous immune globulin (IVIG), a blood product to support healthy immune function. Doctors give IVIG to people who have severe muscle and/or skin problems or symptoms that don't improve with other medicines.

PT and exercise for myositis

PT and exercise can prevent muscle loss and help you function in your daily life.

Your doctor can refer you to a physical therapist and suggest the best workout plan for you.

Lifestyle changes

Along with medicine, a healthy diet can help fight inflammation in the body.

Try to eat a diet heavy in:

  • Fruits and veggies.
  • Lean meats.
  • Plant-based proteins, like nuts, seeds, greens, and beans.

Getting enough rest and learning to manage stress also helps to reduce myositis symptoms or prevent it from getting worse.

Is There a Cure for Myositis?

No, there's no cure for myositis, but early treatment can prevent further muscle weakness.

Many people can build back muscle strength through treatments.

Living with myositis

Although myositis is serious, doctors can treat this disease. People with myositis can live full, healthy lives.

It does require you to see a doctor who focuses on the disease often to make sure treatments are working.

The Myositis Association is a great support group and resource for people with myositis.

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