Myasthenia gravis:
muscle weakness that gets worse as the day goes on

1. What is myasthenia gravis?

For a muscle to contract, the nerve releases the messenger substance acetylcholine at its junction with the muscle (the motor end plate). Acetylcholine docks onto receiving sites (receptors) on the muscle. In myasthenia gravis (literally “serious muscle weakness”), the immune system produces antibodies against precisely these receptors or against neighbouring proteins. The signal then arrives only in weakened form — especially when a muscle has to work repeatedly.^¹,²

This gives the disease its hallmark: the muscles are not permanently paralysed but tire unusually quickly. After a rest, they recover. In the morning many things still go well; by evening the eyelid droops, the voice grows quieter and chewing becomes an effort.^²

Myasthenia gravis is rare, but among rare diseases it is one of the more common ones. There are two age peaks: younger adults, especially women, and older people from around 60, in whom the disease has been recognised much more often in recent decades. One important point up front: myasthenia is very treatable today. With the right treatment, most people affected lead a largely normal life.^¹

2. Types: ocular, generalised, by antibody

The guideline classifies myasthenia by the extent of the symptoms, by age at onset and by the antibodies that can be detected. This classification is not just theory — it helps decide which treatment is an option.^¹

• Ocular myasthenia — only the eye muscles and eyelids are affected: a drooping eyelid (ptosis) and double vision. In a considerable proportion of people, the disease spreads to other muscles within the first two years.
• Generalised myasthenia — the muscles of the face, throat, neck, arms, legs or breathing are also involved.
• Early and late onset — before the age of 50, the thymus (the gland behind the breastbone) is often enlarged; with late onset it usually is not.
• Thymoma-associated myasthenia — in a smaller proportion of people, a usually benign tumour of the thymus gland, a thymoma, lies behind it. As a rule, it has to be removed.

By antibody, the main distinctions are:

3. Symptoms: weakness that gets worse as the day goes on

The key symptom is fluctuating weakness that depends on exertion, without pain and without any loss of sensation. It is usually worse in the evening, in the heat, during infections and under stress.^²

Eyes and face

• Drooping upper eyelid — often on one side or alternating, worse after reading for a long time or working at a screen.
• Double vision — especially when looking to the side or upwards, when driving or watching television.
• Face — the smile looks “flat”, the mouth does not close properly, the face looks tired.

Speaking, chewing, swallowing

• Nasal speech that grows quieter the longer you talk.
• Weak chewing — with tough meat, the jaw needs a break.
• Difficulty swallowing — choking, or liquid coming back up through the nose.

Arms, legs, neck, breathing

• Arms — blow-drying your hair or working overhead becomes difficult.
• Legs — climbing stairs and walking for longer become an effort.
• Neck — the head “drops” forwards.
• Breathing muscles — shortness of breath when lying down or on exertion.

4. Causes: antibodies, the thymus and triggers

Why the immune system turns against the junction between nerve and muscle has not been fully explained. According to current knowledge, several factors work together:^¹,²

• Thymus — the gland in which immune cells “learn” to tell self from foreign plays a central role, especially with early onset. This is what the benefit of thymectomy is based on.
• Thymoma — a tumour of the thymus gland can trigger the misdirected immune response.
• Predisposition — other autoimmune diseases occur together more often than expected, for example thyroid inflammation such as Hashimoto's thyroiditis or an overactive thyroid of the Graves' disease type.
• Factors that make it worse — infections, fever, operations, lack of sleep, heat, heavy exertion, pregnancy and the period after giving birth.

5. Diagnosis: antibodies, nerve tests, thymus imaging

The neurologist makes the diagnosis from the typical clinical picture plus at least one confirming finding: antibodies, electrical nerve tests or a response to a test medicine.^¹

• Examination under strain: the practice asks you, for example, to look upwards or hold your arms out in front of you and measures when the weakness sets in. A standardised myasthenia score later serves as a reference for monitoring the course.
• Ice pack test: a cold pad on the drooping eyelid often improves ptosis briefly in myasthenia — a simple clue, but not proof.
• Antibodies in the blood: first against the acetylcholine receptor; if negative, against MuSK and, if appropriate, LRP4.
• Repetitive nerve stimulation: a nerve is stimulated several times in a row; if the muscle response decreases (decrement), this fits with myasthenia. Single-fibre EMG is even more sensitive.
• CT or MRI of the chest: for every confirmed case of myasthenia, to find or rule out a thymoma.
• Additional tests: thyroid values, lung function and, if needed, imaging of the head to rule out other causes of double vision or swallowing problems — such as a stroke or multiple sclerosis.
• Medication list: all medicines from the past few weeks need to be on the table, including over-the-counter ones — new weakness can be caused by a medicine.

Because the symptoms fluctuate, it helps to note the time and type of weakness over a few days or to photograph it with your phone — for example your eyelid in the morning and in the evening. This captures a picture that may not be visible at that very moment in the consultation.

6. Treatment: the step-by-step approach

Treatment rests on two pillars: medicines that improve signal transmission symptomatically, and immunotherapy that slows down antibody production. According to the guideline, the goal is a state with at most minimal symptoms and as few side effects as possible. Which step you need depends on severity, antibody type, age, thymus findings and your other conditions — the decision is made by the treating practice, ideally in consultation with a myasthenia centre.^¹

Put honestly: the new antibody treatments often work quickly and noticeably, but they are very expensive, not approved for all antibody types and are therefore used selectively in disease that is not adequately controlled with basic treatment. Long-term data covering many years are, by their nature, still lacking.^¹

Thymectomy: surgery on the thymus gland

If there is a thymoma, the thymus gland is usually removed. Without a thymoma, a large randomised trial showed that thymectomy in generalised myasthenia with AChR antibodies in younger and middle-aged adults reduces symptoms and spares cortisone.^¹,³ The effect only sets in after months to years; the operation is planned, not an emergency — and today it is often minimally invasive. It is not recommended with MuSK antibodies.

7. Pyridostigmine, cortisone and azathioprine in everyday life

Pyridostigmine: by the clock and as needed

Pyridostigmine usually starts working within an hour and lasts a few hours. That is why it is taken several times a day, often timed so that its effect is strongest at mealtimes or during demanding activities. For the night there are prolonged-release tablets. The total amount is set by the practice; topping up on your own is not a good idea.^⁴

• Typical side effects: abdominal cramps, diarrhoea, increased saliva and sweating, muscle twitching. They occur because acetylcholine also acts in the gut and on glands.
• Too much also means weakness: an overdose can itself cause weakness (cholinergic crisis) — with heavy salivation, sweating, cramps, muscle twitching and narrow pupils. If the weakness gets worse despite taking it, please do not simply take more; have it checked by a doctor.
• Caution with asthma and a slow heartbeat: pyridostigmine can narrow the airways and slow the pulse; this needs to be weighed up with asthma or heart rhythm disorders.

Cortisone over months

Taken over a long period, cortisone can increase weight, blood sugar and blood pressure, disturb sleep, weaken the bones and increase susceptibility to infection. Bone protection and checks of blood sugar and blood pressure are therefore part of treatment; details in the cortisone guide.^¹

Azathioprine: patience, lab tests and one dangerous combination

• Before starting: the activity of the enzyme TPMT, which breaks down azathioprine, is often measured. If its activity is reduced, there is otherwise a risk of severe damage to the blood count.
• Lab checks: blood count and liver values closely at first, later at longer intervals.
• Allopurinol and febuxostat: these gout medicines block the breakdown of azathioprine. The combination can cause life-threatening damage to the blood count — it is not recommended with febuxostat, and with allopurinol only with a markedly reduced azathioprine dose and close monitoring.^¹
• Protect your skin: long-term immunosuppression increases the risk of non-melanoma skin cancer; sun protection and skin checks make sense.

Vaccinations

Inactivated vaccines, for example against flu, pneumococci, COVID-19 or shingles, are recommended for people with myasthenia; live vaccines are generally off limits under immunosuppression. Ideally, your vaccination status is checked before starting immunotherapy, see Vaccines and medications.^¹

8. Medicines that can make myasthenia worse

This is where people with myasthenia can contribute most themselves. Many common medicines weaken transmission between nerve and muscle even further. Not all of them are forbidden — often it is a matter of weighing up, dose and monitoring. But every new prescription should be checked with your myasthenia in mind.^¹,⁵

This list is not complete. Some statins, benzodiazepines and medicines for heart rhythm disorders have also been linked to worsening. The Deutsche Myasthenie Gesellschaft (German Myasthenia Society) provides a detailed list and an emergency card.^⁵ In practice, this means: combine every new prescription — including at the dentist, in the emergency department or at the pharmacy — with the words “I have myasthenia”. A check with the interaction check and the guide Taking antibiotics correctly helps with that conversation.

9. Myasthenic crisis, surgery and pregnancy

Myasthenic crisis

In a crisis, the breathing or swallowing muscles fail to such an extent that ventilation or tube feeding may become necessary. Common triggers are infections, unsuitable medicines, operations and stopping immunotherapy. In hospital, treatment consists of immunoglobulins as an infusion or blood purification (plasmapheresis, immunoadsorption), which rapidly reduce the antibodies. With modern intensive care, the outlook today is usually good.^¹,²

Before operations and anaesthesia

Planned procedures should ideally be carried out during a stable phase. The anaesthetist and surgeon need the diagnosis and the complete medication list; the team decides whether pyridostigmine is taken on the day of surgery. More on this in the guide Medications before surgery.

Planning a family and pregnancy

Pregnancy is generally possible with myasthenia but should be planned. The course during pregnancy varies; the myasthenia can get worse particularly in the weeks after the birth. Mycophenolate and methotrexate must be stopped beforehand, pyridostigmine and cortisone are considered acceptable, and azathioprine is often continued after weighing up the pros and cons. Magnesium infusions, as commonly used for pre-eclampsia, are problematic. Some newborns develop temporary muscle weakness (neonatal myasthenia) because maternal antibodies are passed on — the birth should therefore take place in a hospital with a paediatric unit.^¹ The basics are covered in the guide Medications during pregnancy.

10. Everyday life with myasthenia gravis

• Pace yourself — put important things into the hours when your medicine works best, and plan breaks before the weakness comes.
• Time your meals — take pyridostigmine as agreed with the practice so that its effect is strongest when you eat; soft food on bad days.
• Take heat and infections seriously — bring fever down, have infections treated early, avoid the sauna and the midday heat.
• Emergency card and medication plan — always with you, up to date and complete. Instructions under Create a medication plan.
• Exercise in measured doses — moderate, regular training makes sense when myasthenia is stable; pushing yourself to exhaustion does not.
• Driving — do not drive with double vision or a drooping eyelid; clarify your fitness to drive with the practice, see Medications and driving.
• Connect with others — the Deutsche Myasthenie Gesellschaft (German Myasthenia Society) offers advice, regional groups and information for relatives.

Myasthenia demands attention, but it is not a disease you are at the mercy of. Most flare-ups have a trigger — an infection, a new medicine, a forgotten or discontinued tablet. That is exactly where the levers lie in everyday life.

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