Myasthenia Gravis Treatments/Medications and Procedures

Common Side Effects of Myasthenia Gravis Medications: Mestinon and More

Medically reviewed by Kiran Chaudhari, M.B.B.S., M.D., Ph.D.

Written by Vanessa Ling, ND, CNS

Posted on October 28, 2026

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Key Takeaways

Myasthenia gravis symptoms can look different for everyone, and there are many treatment options available that doctors can tailor to each person's unique needs.
Medications for myasthenia gravis fall into several categories, including acetylcholinesterase inhibitors, steroids, immunosuppressants, and newer drug classes like FcRn blockers and complement inhibitors. Each type comes with its own possible side effects, ranging from digestive issues and headaches to more serious concerns like increased infection risk or allergic reactions.
If you notice side effects from your myasthenia gravis medications, it is important not to stop taking them on your own but instead reach out to your doctor, who can help with dose adjustments, prevention strategies, or alternative treatment options.

View all takeaways

Managing myasthenia gravis symptoms can look different for everyone. There are many treatment options that can help, but medications may have side effects that are worth discussing with your doctor.

Learn about common side effects to expect with myasthenia gravis drugs. You’ll also discover how to talk to your doctor about them.

Myasthenia Gravis Medications

Drugs for myasthenia gravis aim to relieve symptoms or suppress the immune system to reduce symptoms. Modern medicine for myasthenia gravis offers doctors the option to tailor your treatment plan to your specific disease profile.

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I haven’t had any side effects

The major drug classes for myasthenia gravis include:

Acetylcholinesterase inhibitors — Help with muscle-related symptoms
Steroids and immunosuppressants — Suppress immune system responses, which may help decrease inflammation and improve symptoms
B-cell-directed drugs — Target B cells to slow the production of autoantibodies that worsen myasthenia gravis
Neonatal Fc receptor (FcRn) inhibitors — Help reduce autoantibody action
Complement inhibitors — May calm an overactive immune pathway in myasthenia gravis

Your care team will consider the risks and benefits of these treatments. They’ll also take into account your symptoms, medical history, and treatment response. Then they can create a treatment plan that’s safe, effective, and tailored for you.

Acetylcholinesterase Inhibitors

Acetylcholinesterase inhibitors are also called cholinesterase inhibitors or anticholinesterases. They’re typically reliable first-line treatments for muscle weakness symptoms related to myasthenia gravis.

Pyridostigmine bromide comes in brand-name and generic products. The brand name drug Mestinon is the oral option. An injectable version of pyridostigmine bromide may be used when someone can’t take drugs by mouth.

The most common pyridostigmine bromide side effects include:

Excessive sweating, salivation, or tearing
Bronchial constriction (tightening of airways in the lungs)
Nightmares
Nausea
Vomiting
Diarrhea
Stomach cramps
Muscle cramps or twitching
Muscle weakness

Digestive issues are among the most common and noticeable side effects. This can present as diarrhea, cramps, or gassiness.

One MGteam member shared, “My biggest side effect from Mestinon was explosive bowel issues. I had been on it for almost a year, so my doctor had me reduce it. But unfortunately, didn’t clear it up, so I had to go off of it.”

One small study looked at people with myasthenia gravis on acetylcholinesterase inhibitors. The researchers noted that 30 percent reported digestive issues, 6 percent had excess salivation, and 4 percent had increased sweating. Many of these side effects can be managed with careful timing and dose titration.

In some cases, taking too much pyridostigmine can cause a cholinergic crisis.

Steroids and Immunosuppressants

Your doctor may suggest corticosteroids or immunosuppressants. These may be added when pyridostigmine doesn’t control myasthenia gravis symptoms.

Steroid medications, such as prednisone and prednisolone, are often used first. Azathioprine is a nonsteroid immunosuppressant.

But if symptoms aren’t well-controlled, severe side effects occur, or disease control needs fine-tuning, your doctor may suggest alternatives, such as immunosuppressants like mycophenolate mofetil, cyclosporine, and methotrexate.

“Prednisone caused a huge rise in blood glucose levels for me, and my A1c jumped to 5.7,” one MGteam member said. “I had hair loss and weight loss of 18 pounds. I was weaned off of that and put on mycophenolate mofetil.”

Common Side Effects of Corticosteroids for Myasthenia Gravis

Common short-term side effects of steroids include:

Edema (swelling)
Hypertension (high blood pressure)
Insomnia (trouble sleeping)
Upset stomach and digestive issues
Weight gain, particularly in the belly, face, and back of the neck

Corticosteroids have several long-term side effects. That’s why doctors are careful with dosing and monitoring when someone takes them.

Taking steroid drugs long term can increase the risk of:

Obesity
Stomach ulcers
Cataracts
Mood swings
Infections
Elevated blood sugar or diabetes
Bone thinning and fractures
Thinning skin

Common Side Effects of Other Immunosuppressive Drugs

Side effects vary among nonsteroid immunosuppressants. Your doctor may recommend regular blood tests to monitor your liver, kidneys, and blood cell counts.

Here are some common side effects:

High liver enzyme levels, light sensitivity, skin rash, and blood count changes can occur when taking methotrexate.
Digestive symptoms, increased infection risk, and blood count changes can occur with mycophenolate mofetil.
Kidney damage, tremor, excess hair growth, high blood pressure, nausea, liver damage, and diarrhea can occur with cyclosporine.

“I had nasty cramps and diarrhea start about 36 hours after the weekly methotrexate,” one MGteam member said. “It lasted a few days.”

B-Cell-Directed Treatments

B-cell-directed drugs are immunosuppressants. They’re given intravenously (IV) to target B cells to reduce autoantibody production. Inebilizumab-cdon (Uplizna) and rituximab are examples of these.

In clinical trials, people with myasthenia gravis on inebilizumab-cdon had:

Headache (15 percent)
An infusion-related reaction, such as itching, rash, fever, or chills (10 percent)
Nose and throat irritation (7 percent)
Cough (7 percent)
Urinary tract infection (7 percent)

Possible side effects and serious risks of rituximab include:

Infusion-related reactions
Issues having a bowel movement
Increased risk of infections
Liver and kidney damage

Neonatal Fc Receptor Blockers

Several FcRn blocker drugs represent a modern class of therapies designed to actively clear harmful autoantibodies from your circulation. These include nipocalimab (Imaavy), rozanolixizumab-noli (Rystiggo), and efgartigimod alfa-fcab (Vyvgart).

Common side effects of FcRn blockers are generally mild and manageable and include:

Headache
Upper respiratory tract infections
Tiredness
Diarrhea
Nausea
Fever
Rash
Nose and throat irritation
Redness or skin discoloration
Injection site reactions

Complement Inhibitors

Several complement inhibitors may be used for myasthenia gravis. These include eculizumab-aeeb (Bkemv, for adults), eculizumab (Soliris, for adults and children over 6 years old), ravulizumab-cwvz (Ultomiris), and zilucoplan (Zilbrysq).

Common side effects of complement inhibitors include:

Headache (19 percent of people who took ravulizumab in clinical trials)
Muscle and joint pain
Increased risk of serious meningococcal infections
Nausea
Injection-site reactions

Less Common Side Effects of Myasthenia Gravis Drugs

Most common side effects of myasthenia gravis drugs can be mild and manageable. But sometimes people have less typical side effects.

For example, some people may notice more body odor. This could be indirectly caused by increased sweating from pyridostigmine bromide or steroids.

The following are possible rare but serious side effects and require immediate medical care:

Allergic reactions to treatments, especially injected myasthenia gravis drugs, can lead to breathing difficulties, swelling, and other symptoms that can be serious.
Rituximab carries a black box warning for serious infusion-related reactions, which can be fatal.
Myasthenic crisis is the worsening of muscle weakness that can cause issues breathing on your own. Some drugs like high-dose prednisone can increase the risk of a myasthenic crisis.

If you’re having trouble breathing, call 911 or seek emergency medical care immediately. Stay in contact with your providers to track whether certain symptoms could be due to treatment. Your care team can also help you manage them.

Talk With Your Doctor

Side effects can make it hard to stick to your myasthenia gravis treatment plan. Even if the side effect you’re having is a common one, you can still talk to your doctor for the best way to manage it.

If you’re taking a new drug, ask your doctor about what to expect, including any common or rare side effects to look out for.

If you or your loved ones notice side effects, don’t stop taking your myasthenia gravis medications. Talk to your doctor about strategies to manage side effects. This may include adjustments in dosages, prevention strategies, treatments for the side effects, or alternative treatments.

References