Myocarditis is an inflammation of the heart’s wall. It is rare and can be very serious. For some it may not cause symptoms.

Healthy Myocardium
normal heart section

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The cause is not always known. Causes that are known fall into one of the following categories:

  • Infectious—bacterial, viral, or fungal
  • Toxic—medications, or exposure to heavy metals, toxins, shock, or radiation
  • Problems of immune system—allergic reactions, heart transplant rejection, or autoimmune disorders

Risk Factors

There are no known risk factors.


Myocarditis may not cause symptoms. Those that do appear are related to the cause and severity. Symptoms may build slowly or come on fast. Some common symptoms include:

  • Flu-like complaints, including fever, fatigue, muscle pain, vomiting, diarrhea, and weakness
  • Rapid or irregular heart rate
  • Chest pain
  • Shortness of breath and respiratory distress
  • Loss of consciousness
  • Sudden, unexpected death

Myocarditis can lead to heart failure.


It can be hard to diagnosis myocarditis. There is no specific test for it. Many other causes of heart problems must be ruled out first.

Your doctor will ask about your symptoms and health history. A physical exam will be done. Tests may include:

  • Blood tests to look for signs of heart distress or infection
  • ECG —shows heart’s electrical activity
  • Biopsy —sample of heart tissue is removed for testing

Tests will let the doctor get images of the heart include:


The first line of treatment is support care. A care plan will help to manage your symptoms and sow or prevent further damage. Care will often require a hospital stay.

When possible the cause will be treated. For example:

Medicine can help to support the heart if heart failure is present. These include:

  • Diuretics
  • Angiotensin-converting enzyme (ACE) inhibitors
  • Beta-blockers

Severe heart damage may require a cardiac transplant. A donor heart will replace the damaged heart.


It is not possible to avoid all myocarditis. To decrease risk of infection that could lead to myocarditis:

  • Wash your hands often.
  • Use latex condoms during sex.
  • Do not use drugs for non-medical reasons.

American Heart Association

National Heart, Lung, and Blood Institute


Health Canada

Heart and Stroke Foundation of Canada


Brady WJ, Ferguson JD, et al. Myocarditis: emergency department recognition and management. merg Med Clin North Am. 2004;22(4):865-885.

Causes and risks of heart failure. American Heart Association website. Available at: Updated May 8, 2017. Accessed November 30, 2017.

Feldman AM, McNamara D. Myocarditis. N Engl J Med. 2000;343(19):1388-1398.

Felker GM, Thompson R, Hare JM et al. Underlying causes and long-term survival in patients with initially unexplained cardiomyopathy. N Engl J Med. 2000;342(15):1077-1084.

Myocarditis. EBSCO DynaMed Plus website. Available at: Updated September 5, 2017. Accessed November 30, 2017.

Last reviewed November 2018 by EBSCO Medical Review Board Michael J. Fucci, DO, FACC  Last Updated: 8/22/2018