Myasthenia gravis (MG) and Guillain-Barré syndrome (GBS) are both rare neurological (nerve-related) autoimmune diseases that cause muscle weakness and fatigue. Doctors often need to rule out a diagnosis of MG when evaluating a possible GBS diagnosis.

However, these two neurological disorders have key differences. People with MG may experience distinct symptoms and disease progression compared to those with GBS. Keep reading to learn eight important differences between GBS and MG.

1. Guillain-Barré Syndrome Directly Affects the Nerves

GBS and MG both disrupt the nervous system but in different ways. GBS occurs when the immune system mistakenly attacks the peripheral nerves — nerves outside the brain and spinal cord that control movement and other functions.

Specifically, in GBS, the immune system damages the myelin sheath, the protective coating around nerves. This damage disrupts nerve signal transmission to the muscles, leading to muscle weakness.

2. Myasthenia Gravis Affects the Muscles

Unlike GBS, MG doesn’t directly affect the nerves. Instead, it targets the neuromuscular junction — the connection between nerves and muscles.

In a healthy neuromuscular junction, nerves release a chemical called acetylcholine, which signals muscles to contract (tighten) and move. In MG, immune system antibodies attack the muscle receptors that receive acetylcholine. As a result, the muscles don’t receive the proper signal to contract, causing weakness.

3. Younger Women Are More Likely To Develop Myasthenia Gravis

Both GBS and MG can affect people of any sex, gender, race, or age. However, GBS is more likely to affect people over the age of 50.

MG is more common in women under 40 and men over 60, according to the U.S. National Institutes of Health.

4. Guillain-Barré Syndrome Starts in the Arms and Legs

GBS symptoms tend to develop suddenly, worsening over hours or days. The first signs may include numbness in the hands and feet, followed by muscle weakness that spreads up the arms and legs to the upper body. Muscle reflexes, such as the knee-jerk response, may weaken or disappear.

In severe cases, weakness can affect the respiratory muscles — the muscles that control breathing — leading to respiratory distress. This means a person may struggle to take deep breaths or get enough oxygen, which can become life-threatening. Speaking and swallowing may also become difficult.

5. Myasthenia Gravis Often Starts in the Face

MG symptoms typically develop gradually and often begin in the facial muscles, affecting movements like blinking and smiling. In fact, about half of people who develop MG experience eye problems linked to muscle weakness, including double vision and ptosis (drooping eyelids).

Other facial problems are less common, but it can be hard to speak and smile with MG. If MG affects the throat, it can also become difficult to swallow.

Unlike GBS, MG muscle weakness fluctuates (changes) with levels of activity. Symptoms tend to worsen with use, and then improve with rest.

6. Guillain-Barré Syndrome Treatment Targets Harmful Antibodies

GBS treatment focuses on removing or neutralizing the autoantibodies — immune system proteins that mistakenly attack the body’s tissues — in this case, the peripheral nerves. There are two main therapies for GBS: plasmapheresis (plasma exchange) and intravenous immunoglobulin (IVIg) therapy.

Plasmapheresis filters harmful antibodies from the blood. Blood is drawn through a catheter (a thin, flexible tube inserted into a vein) and separated into plasma and other components, like red blood cells. The plasma — where the harmful autoantibodies are found — is discarded, and the remaining blood is returned to the body with a plasma substitute.

IVIg therapy introduces healthy antibodies from donors into the bloodstream. These antibodies help counteract the autoantibodies attacking the nerves.

There is no cure for GBS. However, treatment can help prevent further nerve damage and make it easier to recover.

7. Myasthenia Gravis Treatment Targets the Muscles

The goal of MG treatment is to help muscles function properly by improving communication between nerves and muscles and managing the immune system’s response. Treatment options include:

• Anticholinesterase medications — These medications, including pyridostigmine (Mestinon), prevent acetylcholine from breaking down too quickly, allowing nerves and muscles to communicate more effectively.
• Complement inhibitors — These targeted therapies block parts of the immune system that contribute to MG symptoms. They include eculizumab (Soliris), ravulizumab (Ultomiris), and zilucoplan (Zilbrysq), which work by inhibiting C5, a protein involved in the immune response.
• Thymectomy — The thymus gland helps regulate the immune system by producing certain immune cells. Thymectomy (removal of the thymus gland) can help rebalance the immune system and, in some cases, lead to remission — a period when MG symptoms significantly improve or disappear.
• Immunosuppressive medications — Drugs like prednisone reduce immune system activity to limit the production of harmful autoantibodies.
• Plasma exchange and IVIg therapy — These treatments, also used for GBS, can help manage severe MG symptoms by removing or counteracting autoantibodies.

Light exercise — specifically certain low-impact exercises — may help with MG-related muscle weakness. However, because MG symptoms vary, it’s important to talk with a healthcare provider before starting an exercise routine.

As with GBS, there is no cure for MG. However, unlike GBS, MG is generally not considered life-threatening and typically does not shorten life expectancy.

8. Myasthenia Gravis Lasts Longer Than Guillain-Barré Syndrome

GBS is an acute condition, which means that it develops suddenly and typically doesn’t last long. Symptoms can worsen rapidly — sometimes within hours — but the illness itself usually lasts for weeks. Most people begin to recover after two to three weeks, but lingering effects such as weakness, tiredness, and pain can persist for months or even years. In some cases, these symptoms may be permanent.

In contrast, MG is a chronic condition, meaning it develops gradually over weeks or months and can last for years. While some people experience remission, with muscle weakness disappearing either temporarily or permanently, MG is typically a lifelong autoimmune disorder.

Talk to Your Doctor

While MG and GBS share some similarities, they are distinct conditions with different causes, symptoms, and treatment approaches. GBS is an acute condition that develops suddenly and can require urgent medical care, while MG is a chronic autoimmune disorder that can fluctuate over time. If you or a loved one are experiencing muscle weakness, difficulty breathing, or other concerning symptoms, it’s important to seek medical attention promptly. A healthcare provider can perform the necessary tests to determine the cause and recommend the best course of treatment to help manage symptoms and improve quality of life.

Find Your Team

On MGteam, the social network for people with myasthenia gravis and their loved ones, more than 2,800 members come together to ask questions, give advice, and share their stories with others who understand life with myasthenia gravis.

Have you experienced symptoms that could be a sign of MG or GBS? How did you get a diagnosis? Share your experience in the comments below, or start a conversation by posting on your Activities page.