Medically reviewed by Steve Kim, MD on June 29, 2016Written by The Healthline Editorial Team

What Is Myocarditis?

Myocarditis is a disease marked by the inflammation of the heart muscle. This heart muscle is known as the myocardium, which is the muscular layer of the heart wall. This muscle is responsible for contracting and releasing to pump blood in and out of the heart and to the rest of the body. When this muscle becomes inflamed, its ability to pump blood becomes less effective. This causes problems like an irregular heartbeat, and trouble breathing. In extreme cases, it can cause blood clots, heart attack, stroke, or damage to the heart.

Normally, inflammation is a bodily response to any sort of wound or infection. Imagine when you cut your finger. Within a short time, the tissue around the cut swells up and turns red, which are classic signs of inflammation. The immune system in your body is producing special cells to rush to the site of the wound and implement repairs. Sometimes this can help speed along the healing process, but other times, inflammation becomes myocarditis.

What Causes Myocarditis?

Myocarditis is usually caused by viral (most common), bacterial, or fungal infections that make their way to the heart. As the infection tries to take hold, the immune system fights back, releasing chemicals to try to get rid of the disease. This results in inflammation. However, it can backfire and weaken the heart itself. Some autoimmune diseases, like lupus, can cause the immune system to turn against the heart, resulting in inflammation and damage. Often it can be difficult to determine exactly what’s causing the myocarditis, but potential culprits include the following causes.


According to the Myocarditis Foundation, viruses are one of the most common causes of myocarditis. They include coxsackievirus B, the adenovirus (which causes the common cold), and parvovirus B19 (which causes a rash called fifth disease). Other possibilities include echoviruses (gastrointestinal diseases), Epstein-Barr virus (mononucleosis), and rubella (measles).


Rarely, myocarditis can result from Staphylococcus aureus or Corynebacterium diptheriae. Staphylococcus aureus is the bacteria that can cause impetigo and MRSA. Corynebacterium diptheriae causes diphtheria, an acute infection that destroys tonsils and throat cells.


Candida yeast infections, molds, and other fungi can sometimes cause myocarditis.


Parasites are microorganisms that live off of other organisms to survive. They can also cause myocarditis. This is rare in the United States, but more commonly seen in Central and South America (where the parasite T. cruzi causes a condition known as Chagas disease).

Inflammatory Diseases

Diseases that cause inflammation in other parts of the body, like rheumatoid arthritis, can also sometimes cause myocarditis.

What Are the Symptoms?

The dangerous thing about myocarditis is that it can affect anyone, occur at any age, and often proceeds without displaying any symptoms. If symptoms do develop, they often resemble those symptoms one might experience with the flu, such as:

  • fatigue
  • shortness of breath
  • fever
  • joint pain or swelling
  • achy feeling in the chest

Many times, myocarditis may subside on its own without treatment, much like a cut on your finger would eventually heal. Even more serious cases that go on for a long time may never create symptoms of heart failure, but secretly may cause damage to the heart muscle. In other instances, the heart will start to reveal its struggles, with symptoms like shortness of breath, heart palpitations or rapid heartbeat, and congestive heart failure.

How Is It Diagnosed?

Though myocarditis can be difficult to diagnose, your doctor can use several tests to narrow down the source of your symptoms. These tests include:

  • blood test
  • chest X-ray
  • electrocardiogram (ECG)
  • echocardiogram (special ultrasound of the heart)
  • endomyocardial biopsy (sampling of heart muscle tissue)

Blood tests can check for signs of infection or inflammation. A chest X-ray can show any signs of heart failure. An electrocardiogram (ECG) can also detect any abnormal heart rhythms or indicate a damaged heart muscle, and an echocardiogram (ultrasound) may detect any enlargement of the heart. In some cases, an endomyocardial biopsy may be performed so the doctor can examine a small piece of tissue from the heart.

Complications of Myocarditis

Myocarditis can possibly cause damage to the heart from the infection. The body’s response to the virus can also cause damage. The immune system can enter the heart as it fights off the infection. This can ultimately lead to heart failure. These cases are rare, and most patients resume healthy heart activity.

Other complications include an enlarged heart and problems with the heart’s rhythm. A heart transplant may be necessary in rare cases.

Myocarditis is also linked to sudden death, with up to 9 percent of autopsies revealing swelling of the heart. This number jumps to 12 percent when young adults are factored in.

How Is Myocarditis Treated?

Treatment for myocarditis include:

  • anti-inflammatory medication
  • ACE Inhibitors (improves blood flow through the heart’s vessels)
  • behavioral changes, such as rest and a low-salt diet
  • diuretics
  • antibiotics
  • corticosteroids

Treatment depends on the severity of the inflammation. In many cases, the swelling will go down on its own and you’ll recover completely. If swelling continues, your doctor may prescribe anti-inflammatory medications to help the process along. They’ll also likely recommend rest and a low-salt diet. Diuretics may be prescribed to remove the excess fluids from the body. Antibiotics may help treat the infection if it was caused by bacteria, and corticosteroid drugs can help reduce inflammation.

If the heart is having trouble pumping, your doctor may also prescribe medications to help the blood vessels relax and the blood to flow more easily. Almost all these treatments work to ease the workload on the heart so it can heal itself.

In more severe cases, a pacemaker or a defibrillator may be necessary. If the heart is failing, other procedures may be performed in the hospital. When the heart is extremely damaged, doctors may recommend a heart transplant.


There are no steps to help prevent myocarditis, but avoiding serious infections may help. Some of the suggested ways to do so include:

  • practicing safe sex
  • staying up to date with vaccinations
  • proper hygiene
  • avoiding ticks


The outlook for myocarditis is mostly positive. The chance of it recurring is roughly 10 to 15 percent, according to the Myocarditis Foundation. Most people with myocarditis do not have any long-term effects on their heart.

There is still much to be learned about the virus. Doctors believe myocarditis is not inherited, and have found no genes indicating that it is.

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