Tips for Managing the Side Effects of Myasthenia Gravis Drugs

There are several medicines available to control the symptoms of myasthenia gravis (MG). However, just as with all medicines, side effects may occur. The good news is that the side effects of MG medicines are usually manageable.

Acetylcholinesterase inhibitors

The first drug often prescribed for mild to moderate myasthenia gravis (MG) is an acetylcholinesterase inhibitor. Common side effects of acetylcholinesterase inhibitors, especially at higher doses, include:1,2

  • Stomach cramps
  • Diarrhea
  • Muscle twitching and cramps
  • Sweating
  • Too much saliva

Taking these drugs with bland foods like crackers, applesauce, or yogurt may help with the stomach cramps and diarrhea. Antidiarrheal medicines and other drugs may be prescribed to manage the stomach issues that sometimes come with these drugs. Your doctor may lower how much acetylcholinesterase inhibitor you take to reduce muscle twitches, sweating, and too much saliva.3

A cholinergic crisis is a rare complication of taking too high of a dose of acetylcholinesterase inhibitors. The main symptom is weakness, which can make it hard to tell from an MG flare or myasthenic crisis. It is controlled by lowering the amount of acetylcholinesterase inhibitor the person is taking.2

Steroids

Steroids are a cost-effective medicine to control the autoimmune system in a person with myasthenia gravis. However, long-term, high doses of steroids are linked to many health problems. Some side effects of taking steroids for years include:3

  • Anxiety and irritability
  • Avascular necrosis (bone tissue death) in the hips and knees
  • Cataracts or glaucoma
  • Cushing’s syndrome (redistribution of body fat)
  • Depression
  • Fast, irregular heartbeat
  • Fluid retention
  • Raised blood pressure, blood sugar, cholesterol, or triglyceride levels
  • Osteoporosis
  • Problems concentrating or remembering, confusion
  • Shortness of breath
  • Skin thinning and easy bruising
  • Stomach upset and ulcers
  • Trouble sleeping (insomnia)
  • Trouble fighting off infections
  • Weight gain due to increased appetite

Managing side effects

There are several ways to fight the side effects of taking steroids long-term. Doctors often recommend:1,4

  • Taking calcium (1,500 mg/day) and vitamin D (400 to 800 IU/day) to reduce the risk of osteoporosis
  • Taking a histamine H2 blocker to prevent ulcers or stomach upset
  • Taking steroids in the morning to prevent insomnia
  • Taking an antibiotic to prevent certain infections
  • Avoiding crowds and sick people, and washing hands often to lower the risk of catching an infection

Bone density, eye health, blood pressure, and blood sugar levels should be checked regularly to watch for signs of osteoporosis, glaucoma, cataracts, diabetes, and cardiovascular issues. Your doctor may prescribe antibiotics to reduce the risk of infection. Diet and exercise are important to manage weight gain.1,4

Steroid-induced flares

High doses of steroids sometimes contribute to what is called an exacerbation, or flare, of MG symptoms. This side effect is most common in older patients, those with weakness in mouth and throat muscles, and people with severe MG. Due to this potential complication, high doses of steroids often are given in the hospital or clinic where the person can be closely monitored.1

Immune system drugs

If a person with MG needs to reduce the amount of steroids they are taking, or stop taking them completely, other immune system drugs may be prescribed, including:

  • Immunosuppressants
  • Immunomodulators

These medicines are called nonsteroidal immunosuppressants. Examples of nonsteroidal immunosuppressants include:1

  • Mycophenolate mofetil (brand name CellCept®)
  • Azathioprine (brand names Azasan®, Imuran®)
  • Cyclosporine (brand names Gengraf®, Neoral®, Sandimmune®)
  • Tacrolimus (brand names Astagraf®, Envarsus®, Prograf®)
  • Methotrexate (brand names Rheumatrex®, Trexall®)
  • Rituximab (brand names Rituxan®, Ruxience®, Truxima®)
  • Eculizumab (brand name Soliris®)

Depending on the drug, there are a variety of potential side effects, including a higher risk of infection. Your doctor may recommend certain vaccinations or prescribe antibiotics to help prevent you from getting an infection while taking 1 of these drugs.

Plasma exchange and IVIG

Plasma exchange and IVIG are 2 different treatments that temporarily boost the immune system. These treatments are generally well tolerated in people with MG but do have some mild side effects. The most common side effects of plasma exchange include:1

  • Bleeding
  • A drop in blood pressure
  • Arrhythmia (irregular heartbeat)
  • Muscle cramps
  • Allergic reaction to chemicals used in the exchange

Doctors generally avoid using plasma exchange long-term because frequent use causes veins to collapse. When this happens a catheter or port must be installed to deliver the fluid, and this adds a risk of infection.1

The most common side effects of IVIG are mild and include:1

  • Headache
  • Chills
  • Dizziness
  • Fluid retention

These side effects are generally managed by slowing the rate of IVIG flowing into the person’s body.4

It is important to find ways to counteract the side effects of your MG medicines so you are more willing to take your drugs as prescribed. Talk to your doctor about the best approach for you.

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Written by: Jessica Johns Pool | Last reviewed: May 2021