Symptoms of myasthenia gravis 

Muscle weakness is the main symptom of myasthenia gravis. The eye and facial muscles and those that control swallowing are commonly affected.

The symptoms of myasthenia gravis can come on suddenly, but it may take some time before the condition is correctly diagnosed.

Weakness of the eye muscles is often the first symptom to develop in around 50% of cases. However, slurred speech, swallowing problems or neck or limb weakness can occur first. The severity of muscle weakness varies from one person to another.

The muscle weakness of myasthenia gravis isn't usually painful in itself, but people with the condition often experience aching muscles, particularly during, or after, periods of physical activity.

Eyes, eyelids and face

In myasthenia gravis, one or both eyelids may droop (ptosis). There may also be blurred or double vision, often at the end of the day or when a person is tired. Around 90% of people with the condition have problems with their eye muscles at some point.

In some cases, the eye muscles remain the only muscles affected (ocular myasthenia). If this continues for a period of two years or more, it becomes increasingly unlikely for other symptoms of myasthenia gravis to develop.

Where the facial muscles are involved, a person's facial expression may be affected. For example, in some cases, a person may appear to have a "snarling" smile because of lower facial weakness.

Swallowing and breathing

If the muscles around the mouth or tongue become weak, this may lead to difficulty chewing and talking (dysarthria) and may cause husky or quiet speech or a nasal sounding voice.

If tongue or palate weakness develops, this can lead to swallowing difficulties (dysphagia) with coughing and choking symptoms. Sometimes, this leads to recurrent chest infections.

A small number of people with myasthenia gravis also have breathing difficulties, particularly when lying flat in bed or after exercise.

Moderate to severe swallowing or breathing problems may require urgent admission to hospital for medical care.

Limbs and movement

Myasthenia gravis can sometimes affect the muscles of the arms, legs and neck. This can cause mobility problems, such as a waddling gait, head drop and difficulty performing physical tasks such as lifting.

The specific muscles affected (promixal muscles) often leads to difficulty:

  • rising from sitting to standing
  • climbing stairs
  • brushing teeth (particularly with the repetitive action involved)
  • washing hair

Physical activity often leads to tiredness because the muscles are weak.

Page last reviewed: 18/02/2015

Next review due: 18/02/2017