Myasthenia gravis is a rare long-term condition that causes muscle weakness.

It most commonly affects the muscles that control the eyes and eyelids, facial expressions, chewing, swallowing and speaking. But it can affect most parts of the body.

It can affect people of any age, typically starting in women under 40 and men over 60.

Symptoms of myasthenia gravis

Common symptoms of myasthenia gravis include:

The symptoms tend to get worse when you’re tired. Many people find they are worse towards the end of the day, and better the next morning after getting some sleep.

Read more about the symptoms of myasthenia gravis.

When to see your GP

See your GP if you have long-lasting or worrying symptoms that could be caused by myasthenia gravis.

They will ask about your symptoms and medical history.

If your GP thinks you could have a condition like myasthenia gravis, they may refer you to a specialist for tests to help diagnose the condition or look for other possible causes of your symptoms.

These tests may include a blood test, a test of how well your nerves are working and some scans.

Read more about tests for myasthenia gravis.

Treatments for myasthenia gravis

Several treatments are available to help keep the symptoms of myasthenia gravis under control.

These include:

  • avoiding anything that triggers the symptoms – some people find that things such as tiredness and stress make their symptoms worse
  • medication to help improve muscle weakness
  • surgery to remove the thymus gland (a small gland in the chest linked to myasthenia gravis) – read about the causes of myasthenia gravis for more information

If the symptoms get suddenly worse – for example, you develop severe breathing or swallowing difficulties – you may need urgent treatment in hospital.

Read more about how myasthenia gravis is treated.

Outlook for myasthenia gravis

Myasthenia gravis is a long-term condition that typically has phases when it improves and phases when it gets worse.

It usually affects most of the body, spreading from the eyes and face to other areas over weeks, months or years. But in around one in five people, only the eye muscles are affected.

Treatment can usually help keep the symptoms under control. Very occasionally, the condition can get better on its own.

The condition can be life-threatening in severe cases, but it doesn’t have a significant impact on life expectancy for most people.

Cause of myasthenia gravis 

Myasthenia gravis is caused by a problem with the signals sent between the nerves and the muscles.

It’s an autoimmune condition, which means it’s the result of the immune system (the body’s natural defence against illness and infection) mistakenly attacking a healthy part of the body.

In myasthenia gravis, the immune system damages the communication system between the nerves and muscles, making the muscles weak and easily tired.

It’s not clear why this happens, but it has been linked to issues with the thymus gland (a gland in the chest that’s part of the immune system).

In many people with myasthenia gravis, the thymus gland is larger than normal, and in around 1 in 10 people there is abnormal growth of the thymus called a thymoma.

Information about you

If you have myasthenia gravis, your clinical team will pass information about you on to the National Congenital Anomaly and Rare Diseases Registration Service (NCARDRS).

This helps scientists look for better ways to prevent and treat this condition. You can opt out of the register at any time.

Find out more about the register.