Myasthenia Gravis: Symptoms, AChR Antibody Test and Treatment

Myasthenia gravis is a chronic autoimmune disease in which the immune system blocks the signal between nerves and muscles, causing weakness that worsens with use and improves with rest. It often starts with a drooping eyelid or double vision, and it can spread to the face, throat, arms, legs and breathing muscles.

Diagnosis rests on a blood test for acetylcholine receptor (AChR) antibodies, completed when needed by MuSK and LRP4 antibodies, nerve studies and a chest scan of the thymus. There is no cure yet, but most people with myasthenia gravis have a normal life expectancy, and several targeted medicines have been approved since 2021.

Key takeaways

• Myasthenia gravis affects about 20 in every 100,000 people; in the US, estimates range from about 60,000 to more than 70,000 people.
• The hallmark is fatigable weakness: drooping eyelids, double vision, trouble chewing, swallowing or speaking, and weak arms or legs that improve with rest.
• About 85% of people with the disease have AChR antibodies; MuSK and LRP4 antibodies explain some of the rest, and some people are seronegative.
• Treatment combines pyridostigmine, steroids or other immunosuppressants, thymectomy for many AChR-positive adults, and newer complement inhibitors and FcRn blockers.
• Trouble breathing or swallowing is an emergency: call 999.

What is myasthenia gravis?

Myasthenia gravis (MG) is a rare autoimmune disorder of the neuromuscular junction, the tiny gap where a nerve passes its message to a muscle. Normally, the nerve releases a chemical messenger called acetylcholine, which attaches to receptors on the muscle and makes it contract. In MG, antibodies attack these receptors or other proteins of the junction (MuSK, LRP4), so the message arrives weaker than it should.

AChR antibodies also switch on complement, a part of the immune defenses that damages the muscle side of the junction, which is why complement blockers help. MG is an autoimmune disease, so most treatments aim to calm the immune system.

Who gets myasthenia gravis?

MG can start at any age, but it is most common in women around 40 and men after 60. Cleveland Clinic estimates that it affects about 20 in 100,000 people worldwide and about 60,000 people in the US; the Myasthenia Gravis Foundation of America (MGFA) counts more than 70,000 people diagnosed in the US.

It is usually not inherited, but a baby can have a temporary form when the mother's antibodies cross the placenta.

Types of myasthenia gravis

Ocular myasthenia gravis

In ocular myasthenia gravis, weakness stays limited to the muscles that lift the eyelids and move the eyes. Cleveland Clinic notes that it evolves into the generalized form in nearly half of people, so follow-up matters.

Generalized myasthenia gravis

Generalized MG also affects the face, throat (bulbar muscles), neck, limbs and, in severe cases, breathing. Symptoms tend to peak in severity within one to three years of diagnosis.

Causes and risk factors: autoimmunity and the thymus

The trigger is not fully known, but the thymus, an immune gland behind the breastbone, plays a central role. According to Cleveland Clinic, about two-thirds of people with myasthenia gravis have overactive thymic tissue (thymic hyperplasia), and about 1 in 10 have a thymus tumor called a thymoma, usually noncancerous.

Age changes the picture. A 2026 meta-analysis found that people whose MG starts at 65 or older were more often AChR-positive, less often seronegative, and less likely to have a thymoma than people with earlier onset.

MedlinePlus lists thyrotoxicosis, rheumatoid arthritis and lupus as more frequent in people with MG, and Cleveland Clinic cites thyroid disease as a risk factor. Doctors therefore look for conditions such as Graves' disease or lupus at diagnosis.

Myasthenia gravis symptoms

The key feature is weakness that gets worse with activity and better with rest. It can change from day to day, week to week or month to month. MedlinePlus and MGFA describe these myasthenia gravis symptoms:

• drooping of one or both eyelids (ptosis), often the first sign;
• blurred or double vision (diplopia), trouble keeping a steady gaze;
• trouble smiling, chewing, swallowing or talking, a hoarse or changing voice;
• a drooping head from weak neck muscles;
• weak arms, hands or legs: trouble climbing stairs, lifting objects or rising from a chair;
• shortness of breath and profound tiredness.

Eye symptoms have other causes too, and diseases such as multiple sclerosis can affect vision, so get them checked.

Myasthenic crisis

A myasthenic crisis is a severe flare in which the breathing or swallowing muscles become too weak to work safely. It needs hospital care, sometimes a ventilator. Cleveland Clinic estimates that about 20% of people with myasthenia gravis have at least one crisis in their lifetime. MedlinePlus notes that taking too much or too little medicine can bring one on.

How myasthenia gravis is diagnosed

A neurologist starts with your history and a neurological exam that looks for weakness that increases with repeated effort, while sensation and reflexes stay normal. Then several tests confirm the diagnosis.

Acetylcholine receptor (AChR) antibody test

The AChR binding antibody test comes first; blocking and modulating antibodies are added if it is negative but MG is still suspected. Cleveland Clinic reports that about 85% of people with myasthenia gravis have high AChR antibody levels. Testing.com notes that 10% to 15% of people with generalized MG test negative, compared with up to half of people with ocular MG.

No fasting is needed. Rare false positives occur with a thymoma, Lambert-Eaton syndrome or some autoimmune liver conditions.

MuSK and LRP4 antibodies, and seronegative MG

If the AChR test is negative, doctors test for antibodies against muscle-specific kinase (MuSK), found in about 6% of people with MG according to Cleveland Clinic. Next comes LRP4 (low-density lipoprotein receptor-related protein 4): a systematic review found LRP4-positive patients tend to be younger women with mild, often eye-only disease. When all antibodies are negative, the diagnosis of seronegative MG rests on the exam and electrical tests.

Ice pack test

An ice pack is placed on the drooping eyelid; if the eyelid lifts afterward, MG is likely. In a study of 155 people with possible ocular MG, the test had a sensitivity of 86% and a specificity of 79%.

Repetitive nerve stimulation and single-fibre EMG

Repetitive nerve stimulation looks for a drop (decrement) in the muscle response after repeated nerve stimulation. Single-fibre electromyography (EMG) detected 94% of people with ocular MG, with a specificity of 79%. When both tests were negative, MG was very unlikely.

CT or MRI of the chest (thymus)

A CT or MRI scan of the chest looks for a thymoma or an enlarged thymus, and pulmonary function tests measure breathing strength.

Other blood tests

Doctors often add a TSH blood test to screen for thyroid disease, and a CPK (creatine kinase) blood test. A high CK means muscle damage, which points to another cause. An ANA blood test may be ordered if another autoimmune disease is suspected.

Myasthenia gravis test results at a glance

Reference ranges vary between laboratories: always compare your result with the range printed on your own report.

How to read your results

• A positive AChR antibody result with typical symptoms confirms myasthenia gravis. The next step is a chest scan for a thymoma.
• A negative AChR result does not rule MG out, especially when only the eyes are affected. Ask whether MuSK and LRP4 antibodies and an EMG are planned.
• The antibody level at diagnosis does not predict how severe symptoms will be.
• FcRn blockers lower total immunoglobulin G on purpose, so an IgG blood test may come back low during treatment.

Myasthenia gravis treatment

The international consensus guidance (2016, updated 2020) aims for minimal symptoms that do not limit daily life, with as few side effects as possible.

Pyridostigmine: the first medicine

Pyridostigmine (Mestinon) is an acetylcholinesterase inhibitor (ChEMBL): it slows the breakdown of acetylcholine. The guidance makes it part of the initial treatment in most patients. It eases symptoms but does not calm the immune attack.

Steroids and other immunosuppressants

If pyridostigmine is not enough, prednisone or another immunosuppressant is added. Steroids can briefly worsen MG in the first two weeks. Azathioprine, cyclosporine or mycophenolate mofetil are added when steroid side effects or doses are too high; they work slowly and are monitored with blood tests such as a complete blood count. Rituximab is recommended as an early option for MuSK-positive MG that responds poorly to first treatments.

Thymectomy

In the MGTX trial, adults with AChR-positive generalized MG without a thymoma did better over three years with thymectomy plus prednisone than with prednisone alone: lower weakness scores (6.15 vs. 8.99), lower prednisone doses (44 vs. 60 mg every other day) and fewer hospitalisations for flares (9% vs. 37%). The 2020 guidance says thymectomy should be considered early for AChR-positive, nonthymomatous generalized MG at age 18 to 50. Evidence does not support it for MuSK or LRP4 antibody MG.

IVIG and plasma exchange

Intravenous immunoglobulin (IVIG) and plasma exchange, which filters antibodies out of the blood, work within days. They are used for crises, before surgery or when a rapid response is needed; plasma exchange may act faster.

Complement inhibitors: eculizumab, ravulizumab, zilucoplan

These drugs block complement protein C5 in AChR-positive generalized MG.

• Eculizumab: in the REGAIN trial of refractory MG, flares occurred in 10% of patients on eculizumab versus 24% on placebo, although the main analysis was not significant; the 2020 guidance recommends it for severe, refractory disease.
• Ravulizumab, given every 8 weeks, improved the daily-activities score (MG-ADL) by 3.1 points versus 1.4 with placebo in CHAMPION-MG.
• Zilucoplan, self-injected once a day, improved MG-ADL by 4.39 points versus 2.30 in the RAISE trial. The FDA approved it in October 2023.

Blocking complement raises the risk of meningococcal infection: the 2020 guidance requires meningococcal vaccination before eculizumab, and ravulizumab and zilucoplan carry a boxed warning.

FcRn blockers: efgartigimod, rozanolixizumab, nipocalimab

The neonatal Fc receptor (FcRn) recycles IgG antibodies; blocking it lowers all IgG, including AChR antibodies.

• Efgartigimod (Vyvgart), approved by the FDA in December 2021: in ADAPT, 68% of AChR-positive patients responded in the first cycle versus 30% on placebo.
• Rozanolixizumab (Rystiggo), approved by the FDA in June 2023: in MycarinG, with AChR- or MuSK-positive adults, it improved MG-ADL by 3.4 points versus 0.8 with placebo.
• Nipocalimab (Imaavy), approved in April 2025 (see below).

Medicines that can trigger a flare

Several common medicines can worsen MG. MGFA's list includes:

• to avoid: telithromycin, botulinum toxin, D-penicillamine, and quinine except for malaria;
• to use cautiously, if at all: fluoroquinolone antibiotics (ciprofloxacin, levofloxacin, moxifloxacin) and macrolides (azithromycin, clarithromycin, erythromycin);
• to use with caution: aminoglycoside antibiotics, IV magnesium, beta-blockers, procainamide, iodinated contrast dye, chloroquine and hydroxychloroquine;
• statins, at the lowest dose needed (see our article on statin muscle pain and the CK test);
• immune checkpoint inhibitors for cancer, to be discussed with both the oncologist and the neurologist.

Some may still be needed: never stop a medicine on your own, tell every doctor and dentist you have MG, and report any worsening.

Living with myasthenia gravis and preventing flares

MG cannot be prevented, but flares can often be limited. MedlinePlus advises resting during the day, using an eye patch for bothersome double vision, and avoiding stress and heat. Infections and surgery can trigger worsening. In US claims data, steroid use was linked with weight gain, high cholesterol, high blood pressure and infections, so doctors keep the dose low. Carry an emergency card listing your diagnosis and medicines.

Pregnancy, children and older adults

Pregnancy

Most women with well-controlled MG stay stable during pregnancy. A 2026 meta-analysis of 34 studies (3,720 pregnancies) found that symptoms worsened in 30% of pregnancies, most often in the first trimester, and after delivery in 27%. Preterm birth occurred in 9%, and 9% of babies had temporary neonatal MG, which usually fades within three months.

The guidance recommends planning pregnancy in advance. Pyridostigmine and prednisone are preferred; mycophenolate mofetil and methotrexate are contraindicated (birth defects). Thymectomy waits until after pregnancy, magnesium sulfate is not recommended for eclampsia, and newborns are checked for weakness. Ask your care team which blood tests during pregnancy are planned.

Children

Children with only eye symptoms are more likely than adults to go into spontaneous remission and can start with pyridostigmine. They are sensitive to steroid side effects such as slower growth.

Older adults

MG starting after 65 is more often AChR-positive and less often linked to a thymoma. In-hospital mortality averaged 5.0% for MG admissions at 65 and older, versus 1.8% for all adults.

When to see a doctor

See your GP if you notice a drooping eyelid, double vision, or weakness that worsens with use and improves with rest. In the UK, your GP can refer you to a neurologist if symptoms persist.

Call 999 or go to A&E right away if you or someone with MG has:

• shortness of breath or difficulty breathing;
• trouble swallowing saliva, choking, or a voice that becomes very weak;
• rapidly worsening weakness after an infection, surgery or a new medicine.

Latest scientific advances in myasthenia gravis

Nipocalimab joins the FcRn blockers

In the phase 3 Vivacity-MG3 trial (Lancet Neurology, 2025), 196 adults with generalized MG received nipocalimab or placebo every two weeks on top of their usual treatment. In antibody-positive patients (AChR, MuSK or LRP4), MG-ADL improved by 4.70 points versus 3.25 with placebo over 24 weeks, with similar rates of side effects. The FDA approved nipocalimab (Imaavy) on April 29, 2025.

B-cell depletion with inebilizumab

The MINT trial (New England Journal of Medicine, 2025) tested inebilizumab, an antibody that removes CD19-positive B cells, in 238 adults with AChR- or MuSK-positive MG, while steroids were tapered to 5 mg a day. At 26 weeks, MG-ADL improved by 4.2 points versus 2.2 with placebo.

A one-course CAR-T cell therapy

Descartes-08 is a CAR-T cell therapy made from the patient's own cells, given as six weekly outpatient infusions without the usual preparatory chemotherapy (lymphodepletion). In a randomized phase 2b trial (Nature Medicine, 2026), 66.7% of treated patients reached a major improvement at month 3 versus 27.3% with placebo. A larger phase 3 trial with 128 participants (NCT06799247) expects its primary results at the end of 2026.

Less steroid, more targeted care

A 2025 Delphi consensus of 70 specialists from eight countries set a long-term steroid target of 5 mg a day or less, helped by biologic treatments. A US claims study of 8,833 adults found that 42.5% used steroids and that their yearly healthcare costs were more than twice as high ($76,381 vs. $35,309). Trials are also testing efgartigimod in ocular MG (NCT06558279) and in AChR-negative generalized MG (NCT06298552).

Which tests can help?

Lab tests anchor the diagnosis and follow-up of myasthenia gravis:

• AChR binding antibodies, then blocking and modulating antibodies if needed;
• MuSK and LRP4 antibodies when AChR is negative;
• TSH to screen for thyroid disease;
• CK, to look for a muscle disease instead;
• a complete blood count and other monitoring tests during immunosuppressant treatment;
• IgG levels during FcRn blocker treatment;
• ANA or an autoimmune panel when another autoimmune disease is suspected, such as Sjögren's disease.

Glossary

• AChR antibody: an antibody against the acetylcholine receptor, found in most people with MG.
• MuSK: muscle-specific kinase, a protein of the nerve-muscle junction targeted by antibodies in some MG.
• LRP4: another junction protein; antibodies against it occur in some people negative for AChR and MuSK.
• Thymus: an immune gland behind the breastbone; thymectomy is its surgical removal.
• Myasthenic crisis: a severe flare with breathing or swallowing failure.
• FcRn: the neonatal Fc receptor, which recycles IgG antibodies.
• MG-ADL: a 0-24 score of how MG affects daily activities, used in trials.

Frequently asked questions

What are the medical treatment options for myasthenia gravis?

Options include pyridostigmine for symptoms; steroids and immunosuppressants such as azathioprine or mycophenolate; thymectomy; IVIG or plasma exchange for flares and crises; complement inhibitors (eculizumab, ravulizumab, zilucoplan); FcRn blockers (efgartigimod, rozanolixizumab, nipocalimab); and rituximab for MuSK-positive disease.

What are the common side effects of pyridostigmine?

MedlinePlus lists nausea, diarrhoea, vomiting, drooling, cold sweats, blurred vision, an increased urge to urinate, and muscle cramps or weakness. Call your doctor right away for a rash or hives, slurred speech, confusion, seizures or difficulty breathing.

Can berberine help with myasthenia gravis?

There is no evidence in people. The only study found is in rats with an experimental form of MG (2021), in which berberine reduced inflammatory T cells. No human trial has tested it. Ask your neurologist before taking any supplement.

Where can I find online support groups for myasthenia gravis?

In the UK, the charity Myaware offers information and support for people with myasthenia. In the US, MGFA lists virtual (Zoom), hybrid and in-person support groups, searchable by state. It also runs nationwide groups for seronegative MG, young adults, Spanish speakers, caregivers and parents of children with MG, plus a helpline; questions can be sent to [email protected].

Is myasthenia gravis fatal?

Usually not: most people have a normal life expectancy. The main danger is a myasthenic crisis; in US hospitals, in-hospital mortality for MG admissions averaged 1.8% in 2010-2019.

What triggers a myasthenia gravis flare?

Common triggers are infections, surgery, stress, heat, some medicines (certain antibiotics, magnesium, beta-blockers), starting steroids, missing doses or taking too much pyridostigmine, pregnancy and the months after delivery.

What is a normal AChR antibody level?

Normally, there is no AChR antibody in the blood, or less than 0.02 nmol/L by MedlinePlus figures. Some labs use other cutoffs, such as 0.30 nmol/L or below for negative and 0.50 nmol/L or above for positive. A negative result does not exclude MG.

Can myasthenia gravis go into remission?

Yes. Some people reach remission, which MedlinePlus describes as usually temporary but occasionally permanent; thymectomy may lead to lasting remission. Children with eye-only MG are more likely than adults to go into spontaneous remission.

Sources

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• Howard JF et al. — Efgartigimod in generalised myasthenia gravis (ADAPT) — Lancet Neurol, 2021 — doi.org
• Bril V et al. — Rozanolixizumab in generalised myasthenia gravis (MycarinG) — Lancet Neurol, 2023 — doi.org
• Antozzi C et al. — Nipocalimab in generalised myasthenia gravis (Vivacity-MG3) — Lancet Neurol, 2025 — doi.org
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• Vu T et al. — Terminal Complement Inhibitor Ravulizumab in Generalized Myasthenia Gravis — NEJM Evid, 2022 — doi.org
• Howard JF et al. — Eculizumab in refractory generalised myasthenia gravis (REGAIN) — Lancet Neurol, 2017 — doi.org
• Nowak RJ et al. — A Phase 3 Trial of Inebilizumab in Generalized Myasthenia Gravis — N Engl J Med, 2025 — doi.org
• Vu T et al. — BCMA-directed mRNA CAR T cell therapy for myasthenia gravis: phase 2b trial — Nat Med, 2026 — doi.org
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• Giannoccaro MP et al. — Ice pack test and single-fiber EMG in suspected myasthenic ptosis — Neurology, 2020 — doi.org
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• Song J et al. — Berberine attenuates experimental autoimmune myasthenia gravis — J Neuroimmunol, 2021 — doi.org
• Cartesian Therapeutics — Phase 3 trial of Descartes-08 in generalized myasthenia gravis (NCT06799247) — ClinicalTrials.gov — clinicaltrials.gov
• argenx — Efgartigimod in ocular myasthenia gravis (NCT06558279) — ClinicalTrials.gov — clinicaltrials.gov
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• US Food and Drug Administration — FDA Approves New Treatment for Myasthenia Gravis (Vyvgart) — FDA, 2021 — fda.gov
• US Food and Drug Administration — Novel Drug Approvals for 2023 (Rystiggo, Zilbrysq) — FDA — fda.gov
• US Food and Drug Administration — Novel Drug Approvals for 2025 (Imaavy) — FDA — fda.gov
• EMBL-EBI — ChEMBL drug mechanisms — ChEMBL — ebi.ac.uk
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• MedlinePlus — Creatine phosphokinase test — Medical Encyclopedia — medlineplus.gov
• MedlinePlus — TSH test — Medical Encyclopedia — medlineplus.gov
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Further reading

• Autoimmune disease symptoms and lab tests
• Graves' disease: symptoms, TSH, T4 and TRAb tests
• TSH blood test: how to read your results
• CPK blood test: what high creatine kinase means
• Autoimmune panel: ANA, RF and anti-CCP tests
• Multiple sclerosis: symptoms and diagnosis
• Rheumatoid arthritis: symptoms and treatment

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