Last updated:

Reviewed by:

Dr Rhianna McClymont

, Lead GP at Livi

Medically reviewed

Myositis is a rare autoimmune disease that causes weak muscles. Find out about the main types of myositis, what causes it and how doctors treat it.

What is myositis?

Myositis is a rare autoimmune disease causing weak, aching or painful muscles, which usually gets gradually worse over time. There are different types of myositis, and symptoms can vary depending on the type you have.

What causes myositis?

Myosotis is usually caused by the immune system mistakenly attacking the body's muscles, which leads to chronic inflammation.

Experts aren't sure exactly why this happens. It can affect you at any age, but it's thought that factors like genetics, certain viral infections and some medications can play a part.

Types of myositis

There are several different types of myositis. The main two types are:

  • Polymyositis – This type affects different muscles, often in the shoulders, hips and thighs, and sometimes the joints, too. It's more common in women than men and in people aged 30 to 60, although you can get it at any age

  • Dermatomyositis – As well as muscle inflammation and weakness, this type of myositis also causes a rash. It's more likely to affect women and it can also affect children (called juvenile dermatomyositis).

Myositis symptoms

Symptoms of myosotis can differ depending on what type you have, but it generally affects a range of different muscles, especially those around the neck, shoulders, back, hips and thighs.

Common symptoms include:

  • Muscle weakness, aches and pains

  • Tiredness

  • Problems with swallowing

The muscle weakness often gets gradually worse over time and can cause many difficulties with daily activities like sitting up, getting up from a chair, using stairs and lifting things. In more extreme cases, it can become hard to lift a cup of tea or brush your hair.

These effects on daily life can be challenging to adjust to, leading to unhappiness and even depression.

In dermatomyositis, a distinctive red or purple rash usually appears before the muscle weakness, often on the face. It may be itchy or painful.

Myositis diagnosis

See a GP if you experience muscle weakness. They will start by examining you and asking you about your symptoms.

The symptoms of myosotis can be similar to other conditions, so you may need to have tests to help to rule these out. For example:

  • Blood tests

  • Biopsy – A small sample of muscle tissue is taken and analysed for any swelling or other damage

  • MRI scans – Magnetic fields and radio waves are used to give doctors a detailed image of the inside of your body

  • Electromyography (EMG) – Recording electrical signals from the nerve endings in your muscles with a small needle-shaped electrode

Treatment for myositis

If you're diagnosed with myositis, there are a range of treatment options available to help manage your symptoms. Doctors will help find the best treatment plan for you, which usually involves a combination of medication, exercise, diet and other therapies.

  • Medication – Steroids are the main type of medication used to treat myositis, and immunosuppressive medication such as disease-modifying anti-rheumatic drugs (DMARDs) may also be helpful

  • Exercise – Exercise is vital for building up muscle strength and reducing swelling – it will also help to boost your energy levels and your mental health

  • Physiotherapy – A physiotherapist can help you put together an effective exercise plan to help you build up muscle strength

  • Occupational therapy – A specialist will work with you to help with daily activities and to make life in your own home easier

  • Speech therapy – Some types of myositis can cause swallowing problems, which speech therapists can help you to overcome

Living with myositis

Myositis affects everyone differently, and the challenges that you face may be very personal to you. There's no cure for myositis, but many people are able to improve their symptoms with the right combination of treatment.

Living with an ongoing health condition can be stressful and challenging, but there's lots of support available. Talk to your doctor about local support groups, or contact Myositis UK for further help and information.

Last updated:
Reviewed by:
Lead GP at Livi Dr Rhianna McClymont
Dr Rhianna McClymont, Lead GP at Livi