Myasthenia gravis


Myasthenia gravis is an autoimmune condition that causes muscle weakness and muscle fatigue. Antibodies which normally fight infections go wrong and attack the communication system between the brain and your movement muscles which is why you feel weak.

How should the neuromuscular junction work?


The first signs can be droopy eyelids and sometimes double vision. You may also feel generally tired and weak in the neck, arms and legs.

Many people find their faces are affected and talking, smiling or chewing may be difficult. If untreated, swallowing and breathing can become difficult and you should seek immediate medical attention.

Some people find that talking for a long time is difficult and their speech may sound different when they have been talking a lot.

After a good night’s sleep you may feel ok, but as the day wears on the weakness gets worse and you may feel you need a rest. The more you try to do something like walking or talking the harder it gets.


Blood tests are used to detect the antibodies that cause myasthenia. You may be offered a test called electromyography (EMG) to assess muscle activity and a chest CT scan to assess the size and shape of the thymus gland.


Pyridostigmine: Some people can control their myasthenia with enzyme blocking drugs. The drug boosts the message from the nerve to the muscle.

Side effects: Stomach cramps, digestive problems and an urgent need to urinate. Some people may experience increased sweating and production of saliva. Pyridostigmine at higher doses can cause muscle twitching, often around the eyes, and muscle cramps.

Steroids and immunosuppressants: Immune suppressing drugs, including steroids, are often used by people with myasthenia

Azathioprine (Imuran ®) This drug reduces antibody production but can take at least a year to ‘kick in’. It is sometimes used by itself with patients who can't quite manage on Mestinon® alone. More often it is used to enhance the benefits of steroids and/or to get away with lower doses.

Side effects: allergies, liver damage and bone marrow suppression. Regular blood tests are needed roughly weekly and then every two months indefinitely. These are done by the GP. Some patients react to it in the first few weeks with fever, nausea, vomiting, loss of appetite or tummy pain. In this case the drug must be stopped.

Immunosuppressive drugs: The steroid prednisolone is often used (typically on alternate days); doses may have to be built up high before a lower maintenance level is found. Benefits typically kick in after 2-3 months.

Side effects: can include weight gain, hypertension, glaucoma and cataract and / or osteoporosis . Care should also be taken to monitor patients at risk of tuberculosis or peptic ulceration.

Those taking steroids may find they suffer from thinning of the stomach lining causing acid indigestion and potentially stomach ulcers. Other side effects may include mood swings, increased appetite, high blood pressure, increased sweating, increased hair growth and thrush. Prolonged use of steroids can thin the bones. People on steroids are also at an increased risk of infection so should visit their GP at the first sign of illness and not be given live vaccines. Find out more.

For acute exacerbation's there are two treatments that may offer rapid (within a few days) improvement plasma exchange and IVIg. They are of similar efficacy but each presents resource issues and the specialist will decide which is most appropriate. The benefits only last a few weeks, but this gives time for other treatments to become effective.

Plasma exchange: In severe cases people will be admitted to hospital for plasma exchange, an emergency treatment to remove antibodies from the blood, or an infusion of intravenous immunoglobulin. The benefits of these emergency treatments last for about six weeks.

Side effects: feeling faint or light headed, numbness and tingling.

IVIG (Intravenous Immunoglobulin): This treatment takes place in hospital. The treatment involves being injected with normal antibodies from donated blood and this will temporarily change the way your immune system operates.

Side effects: IvIG is a blood thickening treatment so there is a very slight increase in the risk of heart attack and stroke. Read more.

Thymectomy: Some people can control their myasthenia with enzyme blocking drugs, Others may require surgical treatment to remove the thymus gland.

Drugs that can make myasthenia worse

Read More

Myasthenia for complete beginners

A medical guide for people with myasthenia

An A to Z of myasthenia

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