Myositis (polymyositis and dermatomyositis)

Myositis is the name for a group of rare conditions that cause weak muscles. It slowly gets worse over time, but treatment with medicines and exercise can help.

Check if it's myositis

The main symptom of myositis is muscle weakness, which can start very gradually and cause you to trip or fall over a lot.

You may also find it difficult to do things like:

  • get up from a chair
  • climb stairs
  • lift objects, such as a cup of tea
  • comb your hair

There are different types of myositis. Polymyositis and dermatomyositis are the most common.

Depending on the type, other symptoms can include:

  • painful or aching muscles
  • feeling very tired
  • weight loss
  • night sweats
  • a patchy, red rash, usually on the eyelids, face, neck and the backs of the hands – this can look different on brown or black skin
  • problems with swallowing (dysphagia) or breathing

There may be times when your symptoms are better than at other times.

See a GP if:

  • you have symptoms of myositis

What happens at your appointment

If a GP thinks you have myositis, they will do a blood test and refer you to a specialist.

The specialist may do more tests, including:

  • blood tests
  • an MRI scan
  • an electromyography (EMG) scan to look at the electrical activity in your muscles
  • a biopsy to take samples of your muscle

Causes of myositis

It's not clear what causes myositis, but it may be passed on from your parents in your genes.

Most types of myositis are autoimmune conditions, where the body's immune system attacks itself, causing swelling of the muscles and joints.

Treatment for myositis

It's not possible to cure myositis, but treatment can help control the symptoms.

Treatment usually includes:

  • medicines, such as steroids, to reduce swelling and stop your immune system attacking your body
  • physiotherapy to help you stay active and improve your muscle strength

If your myositis is severe or gets worse, you may be offered other treatments to stop your immune system's response.

These can include:

  • medicines, including some usually used to treat rheumatoid arthritis
  • immunoglobulin therapy, which uses antibodies (part of the immune system) taken from blood donations

You may also be offered speech and language therapy if you have difficulties swallowing or communicating.