The word myositis simple means inflammation of the muscles.  Myositis is a group of rare conditions that effect the muscles, typically around the shoulders, hips and thighs.  It can also affect the heart and lungs, and the muscles that support breathing and swallowing.  There are 2 main types of myositis – polymyositis and dermatomyositis.  “Poly” means many, so polymyositis means many muscles are affected.  “Derma” means skin, so this type of myositis can cause a rash as well as the muscle symptoms.   Myositis is believed to be an auto-immune condition.  There are other forms of myositis which are rarer.

What are the symptoms?

Symptoms can vary from person to person, but typically include

  • generally feeling unwell
  • weight loss
  • muscles feeling tired after everyday tasks
  • muscle swelling, or tenderness to touch
  • night sweats
  • falling over
  • there can be a rash, which is linked to the dermatomyositis

These symptoms can also represent other conditions or side effects from medication, so myositis can be tricky to diagnose.

man rubbing his shoulder

Who is affected?

Myositis can affect anyone at any age, including children.  In the UK, it is thought there are 6-8 people per 100,00 with a form of myositis, but detection of the disease is improving so these numbers are likely to increase.  It typically presents between the ages of 30-60 years, but there is also a peek around the mid-teens.

Why does it happen?

The cause of myositis remains unknown, but it is thought there could be both genetic and environmental factors.  But there is no way to predict who may be affected.



Immediate treatment for myositis is often steroids, and flares of the condition may also be managed with steroids.  Exercise is really important and you should be offered physiotherapy to help you plan an exercise regime appropriate to you.  If on reducing steroids symptoms return, you may be offered other medical treatments such as:

  • Disease modifying medication to reduce inflammation such as methotrexate, azathioprine or mycophenolate.  These medications should also help you reduce your steroid dose or come off the steroids completely.
  • Medications such as rituximab and cyclophosphamide may be used if your disease doesn’t respond to the conventional medications.

Myositis usually responds well to treatment, although treatment with some medication is likely to be life-long.

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