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:

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

Depending on the type, other symptoms can include:

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

Non-urgent advice: 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:

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:

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

These can include:

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


Find out more:

Page last reviewed: 26 May 2023
Next review due: 26 May 2026