MS vs. Myasthenia Gravis: How To Tell the Difference

Medically reviewed by Syuzanna Simonyan, M.D.

Written by Emily Van Devender

Posted on October 26, 2026

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Key Takeaways

Myasthenia gravis (MG) and multiple sclerosis (MS) are both autoimmune conditions that affect the nervous system, but they differ in important ways that are worth understanding.
Both conditions can cause muscle weakness and vision problems, but MG specifically affects the neuromuscular junction, leading to issues like droopy eyelids and trouble swallowing, while MS damages the myelin sheath in the brain and spinal cord, which can lead to symptoms like tingling, balance problems, and memory changes. Although there is no cure for either condition, treatments are available that can help manage symptoms and improve quality of life for people living with MG or MS.
If you or someone you care about is experiencing muscle weakness or other nervous system symptoms, reaching out to a doctor is a helpful first step, as they can review your symptoms and may refer you to a neurologist for a thorough evaluation.

View all takeaways

On the surface, two conditions affecting the nervous system can appear quite similar. They may have shared symptoms from their effects on the nervous system or require similar diagnostic tests and treatments. Myasthenia gravis (MG) and multiple sclerosis (MS) share some similarities, but a deeper look reveals important differences between the two conditions.

Learning more about myasthenia gravis and MS can help you distinguish the two conditions more easily, whether they affect you or someone you care about. Here, we compare their disease courses, symptoms, tests, and treatments.

The Main Similarity Between MS and MG

MS and myasthenia gravis are both autoimmune diseases that involve damage to the nervous system. In an autoimmune disease, the immune system that normally protects you from infections and other health problems turns against certain organs or tissues and damages them. In the case of both myasthenia gravis and MS, the nervous system is the target.

Myasthenia gravis and multiple sclerosis are both autoimmune diseases that involve damage to the nervous system. In myasthenia gravis, it’s the neuromuscular junction that’s affected, while in MS, it’s the myelin sheath.

An overactive immune system in both MS and myasthenia gravis leads to inflammation, another common factor between the two conditions. Inflammation can be beneficial because it promotes healing, but prolonged inflammation from a faulty immune system response can do more harm than good.

How MG and MS Affect the Nervous System Differently

Myasthenia gravis and MS both involve immune responses that can damage parts of the nervous system, which can result in some common symptoms between the two conditions, such as muscle weakness. However, they don’t involve damage to the same parts of the nervous system.

MG and the Neuromuscular Junction

In myasthenia gravis, immune proteins called antibodies damage specific chemical receptors at the neuromuscular junction, which is where nerve cells communicate with muscle fibers. These receptors are supposed to respond to a neurotransmitter called acetylcholine, which is a chemical that tells muscles when to contract.

When antibodies damage acetylcholine receptors in myasthenia gravis, muscles cannot receive the proper communication from nerves on when to contract. This leads to muscle weakness or dysfunction in various parts of the body.

MS and the Myelin Sheath

In MS, the immune system targets a different part of the nervous system entirely. The damage is in the central nervous system (CNS), which includes the brain and spinal cord. More specifically, MS damages myelin, the substance that covers nerve fibers. Myelin forms the myelin sheath, which is a protective coating around nerve fibers that helps electrical signals travel quickly and smoothly.

The immune system of a person with MS can also cause direct damage to nerve cells in the brain, as damage to myelin can eventually lead to damage to the underlying nerve fibers, which causes the outermost layer of the brain to shrink over time.

Areas of scar tissue resulting from damage to myelin and nerve cells in MS are called lesions or plaques. MS symptoms and their severity depend on where those lesions or plaques are located within the CNS.

Symptom Patterns: What Each Condition Looks and Feels Like

There’s some symptom overlap between MS and myasthenia gravis, which isn’t surprising when you consider how both conditions can interfere with nerve signals to muscles. However, there are also major differences in how symptoms start, present, and progress.

Common Symptoms of MG

Myasthenia gravis symptoms can appear suddenly, and their severity varies from person to person. Not all people with myasthenia gravis experience the exact same symptoms, but some of the most common symptoms are:

Droopy eyelids
Double vision
Weakness in the hands or arms
Leg weakness
Neck weakness
Trouble swallowing
Weak facial muscles resulting in changed facial expressions
Shortness of breath
Speech or swallowing problems

People with myasthenia gravis are also at risk of a myasthenic crisis, which is unique to myasthenia gravis. A myasthenic crisis can happen when an infection, stress, medication, or another trigger leads to sudden and severe breathing problems. It’s an emergency that requires immediate medical care whether or not the trigger is able to be identified.

Common Symptoms of MS

The disease course of MS is different for each person, with some people experiencing recurrent attacks between periods of disease activity (relapsing-remitting MS) and others experiencing symptoms that progressively worsen over time. Others may experience a single MS attack with a complete or near-complete recovery, though nerve damage may be found on an MRI scan.

Common symptoms of MS that often appear early on in the disease include problems related to muscle weakness or inflammation. They can include:

Muscle weakness in the arms or legs
Muscle stiffness or spasms
Tingling, numbness, or pain throughout the body
Clumsiness and balance problems
Poor bladder control
Dizziness, which may be constant or only sometimes
Vision problems

Some people with MS also experience symptoms related to how MS affects the brain. These can include mood changes, mental fatigue, trouble concentrating, or memory problems.

Shared Symptoms Seen in MS and MG

Both MS and myasthenia gravis can cause muscle weakness in various parts of the body, including the arms and legs. However, muscle weakness can look a little different between the two conditions. For example, muscle weakness in MS can come with stiffness, spasms, or pain. Muscle weakness in myasthenia gravis is more likely to result in complications like speech, breathing, or swallowing problems.

Both MS and myasthenia gravis can cause muscle weakness in various parts of the body, including the arms and legs. However, muscle weakness can look a little different between the two conditions.

Eye and vision problems can also occur in both myasthenia gravis and MS. People with myasthenia gravis may experience weakness in muscles around the eyes, which can cause droopy eyelids over one or both eyes. They can also experience blurry or double vision as a result of MG’s impact on the eye muscles.

For people with MS, double vision is also a concern. MS can also cause inflammation of the optic nerve, which can lead to painful eye movements or blurred or reduced vision.

How Doctors Tell MS and MG Apart

Doctors evaluate neurological symptoms with in-depth testing, which can help them tell conditions like MS and myasthenia gravis apart and make accurate diagnoses. They start with a complete medical history and physical examination. A neurological exam can help them evaluate specific factors like muscle strength and coordination.

Tests for MG

After a neurological exam, doctors may proceed with electrodiagnostic tests to confirm an myasthenia gravis diagnosis. Tests like repetitive nerve stimulation or single-fiber electromyography (EMG) measure your nerves’ electrical responses and can tell your doctor more about how your nerves and muscles communicate.

A blood test that looks for acetylcholine receptor antibodies can also help diagnose myasthenia gravis. However, some people with myasthenia gravis don’t have antibodies that would indicate any immune system dysfunction. For this reason, a blood test may not be necessary to confirm an myasthenia gravis diagnosis.

Additional tests may help rule out conditions that are similar to myasthenia gravis.

Tests for MS

Although there isn’t a singular diagnostic test for MS, several tests can help doctors rule out other conditions that may cause similar symptoms. Most often, they use MRI scans to look for plaques or lesions on the brain and spinal cord that might come from MS. Imaging of the optic nerve can show inflammation that causes eye symptoms like pain or vision loss.

Doctors might also recommend a lumbar puncture to collect cerebrospinal fluid, which may contain inflammatory cells that suggest an autoimmune disease like MS.

Is It Possible To Have Both Conditions?

It’s possible to have both MS and myasthenia gravis, though there aren’t many reported cases.

In documented cases of myasthenia gravis and MS, both conditions tend to be mild.

Some health experts believe the overlap is more common than the research suggests, but because of overlapping symptoms, some people with both MS and myasthenia gravis may only ever be diagnosed with one or the other.

Treatments for MG vs. MS

There’s no cure for myasthenia gravis or MS at this time, but treatments can help with managing symptoms and improve quality of life.

Treatment for myasthenia gravis focuses on reducing muscle weakness symptoms by improving signaling between nerves and muscles and slowing the production of acetylcholine receptor antibodies.

Anticholinesterase medications, for example, help slow the breakdown of acetylcholine at the neuromuscular junction so that muscles can function more normally. People with myasthenia gravis may also be prescribed immunosuppressants to help stop the immune system from producing harmful antibodies.

Treatment for MS focuses on slowing disease progression and reducing the number of relapses, often with disease-modifying therapies. These treatments help reduce inflammation in MS attacks, which helps control damage to the CNS.

Doctors may also recommend strategies to target specific symptoms, like physical therapy for balance problems and muscle weakness.

Tell Your Doctor About Muscle Weakness Symptoms

Identifying the cause of muscle weakness symptoms requires careful specialist evaluation. If you notice possible signs of MS or myasthenia gravis in yourself or a loved one, get in touch with your doctor. They can review your symptoms and medical history and may refer you to a neurologist for further evaluation.

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