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What is myocarditis?

Myocarditis is a condition where the heart muscle becomes inflamed. Specifically, this is an infection of the myocardium, which is the middle layer of the heart wall. The leading cause of myocarditis is an infection, although the exact cause is not always known. It is a rare heart condition that can affect someone slowly over time or come on quickly.

Myocarditis affects the muscle cells and electrical system of the heart, causing heart inflammation. In severe cases, it interferes with the heart’s ability to pump blood to the rest of the body. When this happens, it puts you at increased risk of a stroke or heart attack. The most severe cases of myocarditis lead to cardiomyopathy, heart failure, lung failure, or life-threatening cardiac shock.


What are the symptoms of myocarditis?

Symptoms of myocarditis are not always obvious. It's possible to have the condition and not have any symptoms. Those who do have symptoms of myocarditis often compare the feeling to that of a viral infection or the flu, including body aches, sore throat, joint pain, fever, headaches, or diarrhea. 

Other myocarditis symptoms include:

  • A rapid and irregular heartbeat known as an arrhythmia, or heart fluttering
  • Chest pain and shortness of breath (during physical activity or at rest)
  • Fatigue
  • Swelling of the legs, ankles, and feet
  • Lightheadedness

Myocarditis in children is possible too. The signs of myocarditis in children may be similar to that of adults, but they could also experience fainting or rapid breathing.

What are the types of myocarditis?

There are several types of myocarditis and acute, chronic, and lymphocytic are three examples.

A viral infection most commonly causes acute myocarditis, but the cause is unknown in about 50% of cases.

Chronic myocarditis is associated with a longer duration of the condition and treatment time. It is most often a result of a persistent inflammatory condition, such as an autoimmune disorder.

This condition often occurs after a virus and is one of the rarer types of myocarditis. It requires acute care and hospitalization.

What causes myocarditis?

Myocarditis is most often caused by infection from viruses, such as the common cold, COVID-19, mononucleosis, or gastrointestinal infections. Myocarditis can also be caused by bacterial infections, such as staphylococcus, streptococcus, parasites, or fungus.

Certain medications and radiation treatments can cause myocarditis, as well as other inflammatory diseases. Medications such as antidepressants, heart medicines, seizure medication, antibiotics, diuretics, and benzodiazepines are all linked to an increased risk of myocarditis. It is also possible to develop it without knowing the cause.

What are myocarditis risk factors?

Myocarditis occurs more often in young adult males, but females and individuals of any age can develop the condition. 

Individuals with the following conditions may be at greater risk for developing myocarditis: 

  • Diabetes
  • Skin infections
  • Various types of cancers
  • Kidney disease
  • Chest injuries
  • Eating disorders 

In addition to medications, some procedures can also cause a higher chance of myocarditis in individuals. Patients on dialysis and those receiving radiation treatments or treatments for heart problems are at higher risk for developing it.

How is myocarditis diagnosed?

A physician can listen to the heartbeat through a stethoscope during an examination and make an initial myocarditis diagnosis. The patient’s medical history will be reviewed, and tests will likely be ordered to confirm myocarditis.

Common tests used to diagnose myocarditis include blood tests, positron emission tomography (PET) scan, chest X-ray, electrocardiogram (EKG or ECG), or an echocardiogram (an ultrasound of the heart). In rare cases, a magnetic resonance imaging (MRI) or endomyocardial biopsy will be needed for testing.

How to treat myocarditis

In cases of mild myocarditis, medication, rest, and recovery may be all that is needed for it to go away on its own. Antibiotics are often prescribed if an infection is the suspected cause of myocarditis. Most cases improve with this standard medical therapy and need no further intervention for the heart to return to its normal function and rhythm.

In addition to treating an infection, doctors often prescribe other medications such as ACE inhibitors for lowering blood pressure, corticosteroids for reducing inflammation, and diuretics to decrease fluid buildup. Beta blockers may also be used to help restore the natural heart rhythm.

Surgical treatments

Surgery may be necessary in rare cases when the myocarditis has led to heart failure or an abnormal heart rhythm. Inserting a pacemaker or another device could be an option. If myocarditis does not improve and heart failure continues to worsen, even with previous treatments, a patient may be evaluated for a heart transplant.

Myocarditis prevention

There is no specific way to prevent myocarditis, but there are several steps someone can take to limit the chance of infections, which could lead to myocarditis.

Decreasing the chance of infection includes frequent hand washing, which not only reduces the risk but also decreases the chance of spreading infection. Limiting contact with other individuals known to be sick and avoiding risky behaviors, such as unprotected sex or using illegal drugs, are also advised. Staying up to date on vaccines, such as the COVID-19 and influenza vaccines, is also recommended for decreasing the chance of infection.

How to live with myocarditis

Myocarditis is treatable, and most people can live with the condition, especially when taking proper medications and other precautions prescribed by the doctor. It is possible for myocarditis to reoccur, although this risk is small.

Lifestyle changes may be in order too. The doctor may advise that you limit salt and alcohol intake and possibly refrain from exercise. Quitting smoking and the use of any tobacco products is also necessary. Keeping up with doctor’s appointments and reporting any symptoms of myocarditis to the doctor is an essential part of treatment.

Learn more about when to see a heart specialist and what to expect during your first cardiologist visit.


Myocarditis may go away on its own with only medication needed for treatment. In rare cases, myocarditis can lead to heart failure, stroke, or cardiac shock, which are life-threatening emergencies.

Myocarditis is more common in young adult males, but anyone—including children and females—can develop myocarditis.

In rare cases, the Centers for Disease Control (CDC) reports cases of myocarditis have been associated with the COVID-19 vaccination, specifically the Pfizer-BioNTech or Moderna vaccines. These rare cases typically occur in the young male population, most often after the second dose and within a week of the vaccination. Most patients diagnosed with myocarditis after vaccination fully recovered with medications and returned to normal activities once symptoms improved.

Pericarditis is inflammation of the heart's outer lining, compared to myocarditis, which is inflammation of the middle layer. The CDC has reported that both pericarditis and myocarditis can occur in rare cases after receiving either the Pfizer-BioNTech or Moderna vaccine, typically after the second dose and most often within a week of receiving the vaccine. 

Most patients diagnosed with pericarditis due to the COVID-19 vaccines made a full recovery with proper medication and rest. The CDC continues to monitor and evaluate data regarding myocarditis and pericarditis associated with the COVID-19 vaccines.