Skip to main content

Myasthenic Crisis

Medically reviewed by Last updated on Jul 4, 2022.

What is a myasthenic crisis?

A myasthenic crisis is a severe form of myasthenia gravis. It is a life-threatening condition that happens if the muscles you use for breathing become very weak. It can cause severe breathing problems and lead to lung failure.

What increases my risk for a myasthenic crisis?

A myasthenic crisis may occur for no known reason. Anything that worsens your myasthenia gravis may lead to a myasthenic crisis. Any of the following may trigger or increase your risk for a myasthenic crisis:

  • Fevers, coughs, colds, and lung infections, such as pneumonia
  • A tumor of your thymus (a gland in your chest)
  • Aspiration pneumonitis caused by breathing in stomach acid or vomit
  • Thyroid disease
  • A change in medicines
  • Monthly periods or pregnancy
  • Stress from trauma, surgery, or emotional upset
  • Some contrast dyes used in imaging tests, such as CT scan or MRI

What are the signs and symptoms of a myasthenic crisis?

Your myasthenia gravis symptoms worsen during a myasthenic crisis. You may also have any of the following:

  • Difficulty breathing or speaking
  • The skin between your ribs, around your neck, or on your abdomen pulls in when you breathe
  • Morning headaches, or feeling tired during the daytime
  • Waking up frequently at night or feeling like you are not sleeping well
  • Weak cough with increased secretions (mucus or saliva) or an inability to clear secretions
  • Weak tongue, trouble swallowing or chewing, and weight loss

How is a myasthenic crisis diagnosed?

  • Blood gases may be checked if you are having trouble breathing. Blood is taken from an artery, usually in the wrist. Your blood is tested for the amount of oxygen and carbon dioxide in it. The results can tell healthcare providers how well your lungs are working.
  • Chest x-ray: This is a picture of your lungs and heart. It may show signs of an infection, such as pneumonia. Chest x-rays may also show fluid around your heart and lungs.
  • CT scan: This test is also called a CAT scan. An x-ray machine uses a computer to take pictures of your chest. It is done to check your lungs, heart, and blood vessels. It is also used to check for an enlarged thymus gland. You may be given dye before the pictures are taken to help healthcare providers see the pictures better. Tell the healthcare provider if you have ever had an allergic reaction to contrast dye.
  • MRI: This scan uses powerful magnets and a computer to take pictures of your chest. This test is also used to check for an enlarged thymus gland. You may be given dye to help the pictures show up better. Tell the healthcare provider if you have ever had an allergic reaction to contrast dye. Do not enter the MRI room with anything metal. Metal can cause serious injury. Tell the healthcare provider if you have any metal in or on your body.
  • Pulmonary function tests (PFTs) show how well your body uses oxygen. You breathe into a mouthpiece connected to a machine. The machine measures how much air you breathe in and out over a certain amount of time. PFTs help your healthcare providers decide the best treatment for you.

How is a myasthenic crisis treated?

A myasthenic crisis is an emergency condition that needs to be treated quickly. The goal of treatment is to make your muscles stronger so you can breathe better. Treatment may prevent your lungs from failing. You may need the following:

  • Breathing support:
    • Endotracheal tube: This is also called an ET tube. It is put into your mouth or nose to keep your airway open. It may be attached to a ventilator to help you breathe, and you may get extra oxygen through your ET tube. You will not be able to talk while the ET tube is in place.
    • Bilevel positive airway pressure: This is also called a BiPAP. It is a device that helps you breathe easier.
    • Suctioning: This may help remove secretions from your airway so you can breathe easier.
  • Medicines:
    • Anticholinesterase medicine: This medicine helps improve energy and strength.
    • Immunosuppressives: This medicine is used to slow down your immune system and slow the progression of myasthenia gravis.
    • Immune globulins: This is given as a shot or an IV infusion to help your immune system. Each infusion can take 2 to 5 hours.
  • IV fluids: These may be given to prevent your blood pressure from becoming too low. IV fluids may also help replace any lost fluids and electrolytes (salts) from your body. Conditions such as a fever may cause you to lose fluids from your body.
  • Plasma exchange: This is a procedure that removes plasma from your blood and replaces it with plasma from a donor. Liquid saline may also be used to replace your plasma.

Treatment options

The following list of medications are in some way related to or used in the treatment of this condition.

View more treatment options

What are the risks of a myasthenic crisis?

Use of a ventilator to help you breathe may cause an infection or damage to your lungs. The catheter tube used during plasma exchange may cause an infection. Myasthenia gravis increases your risk for abnormal heartbeats or a blood clot in your lungs. If a myasthenic crisis is left untreated, your breathing muscles may continue to weaken. It may be very hard for you to breathe on your own, and your lungs may stop working. This is life-threatening.

Where can I find support and more information?

  • Myasthenia Gravis Foundation of America, Inc.
    355 Lexington Avenue, 15th Floor
    New York , NY 10017
    Phone: 1- 800 - 541-5454
    Web Address:

When should I contact my healthcare provider?

  • You have diarrhea or an upset stomach after you take your medicine.
  • You have a fever, cough, or a cold.
  • You have morning headaches.
  • You miss taking any of your medicines used to treat your myasthenia gravis.
  • You have questions about your condition, medicine, or care.

When should I seek immediate care or call 911?

  • You suddenly have trouble breathing or swallowing.
  • You suddenly have trouble talking.
  • Your symptoms worsen even after you take your medicines.

Care Agreement

You have the right to help plan your care. Learn about your health condition and how it may be treated. Discuss treatment options with your healthcare providers to decide what care you want to receive. You always have the right to refuse treatment. The above information is an educational aid only. It is not intended as medical advice for individual conditions or treatments. Talk to your doctor, nurse or pharmacist before following any medical regimen to see if it is safe and effective for you.

© Copyright IBM Corporation 2022 Information is for End User's use only and may not be sold, redistributed or otherwise used for commercial purposes. All illustrations and images included in CareNotes® are the copyrighted property of A.D.A.M., Inc. or IBM Watson Health

Learn more about Myasthenic Crisis

Treatment options

Symptoms and treatments

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.