Myocarditis, a disease that inflames and damages the heart muscle, is caused by a viral infection or (less frequently) a bacterial or fungal infection that reaches the heart.

The inflammation of the myocardium – a thick, muscular layer in the middle of the heart -- is actually a byproduct of infection-fighting chemicals released by the body’s immune system. Those chemicals can also weaken the heart.

Myocarditis, though uncommon, is responsible for up to 20 percent of sudden death in young adults, according to the Myocarditis Foundation.


It’s possible to have myocarditis without a single symptom. Occasionally, symptoms might resemble the flu.

More obvious symptoms:

  • Chest pain, possible similar to a heart attack.
  • Shortness of breath.
  • Fatigue.
  • Swelling/Edema.
  • Flu-like: Fever, muscle aches, headache, sore throat, rashes, diarrhea.
  • Liver congestion.
  • Joint pain.
  • Palpitations (abnormal heartbeat).
  • Leg swelling.
  • Rapid heartbeat.
  • Rapid breathing.
  • Poor circulation (paleness, cool hands and feet).
  • Sudden death (young adults).


Myocarditis is caused most often by a viral infection, which sets off a chain reaction in the heart. First comes infection-related inflammation, which then activates the body’s immune system. To eliminate the intruding disease, the immune system releases chemicals that can, in fact, fight inflammation but also weaken the heart.

Here are some of the viruses that can cause myocarditis:

Coxsackievirus B: Can cause the flu or attack the heart. It’s responsible for most cases of myocarditis in the United States. It’s spread through fecal matter. (Wash your hands!)

Adenovirus: Causes the common cold and respiratory infections. It’s spread by an infected person’s cough or sneeze or even touching something with the virus on it before touching your eyes, mouth or nose.

Parvovirus B19:  Causes a mild rash that usually affects children. It’s spread through an infected person’s cough or sneeze and also blood. A pregnant woman infected with the virus can pass it to her baby.

Bacterial infections (like Lyme disease and streptococcus) also can cause myocarditis. Less commonly, myocarditis has been linked to radiation, reaction to chemotherapy medications and other drugs, fungus or parasites, environmental exposure to certain chemicals and an autoimmune disorder that causes widespread inflammation.


In less severe cases, swelling will not require treatment. It will go away on its own. If swelling persists, your doctor might prescribe an anti-inflammatory or, if it’s caused by a bacterial infection, antibiotics.

Other options:

  • Steroids: Reduces swelling.
  • Diuretics Removes the body’s excess water.
  • Intravenous immunoglobulin: Includes antibodies needed to fight infection and reduce swelling.
  • ACE inhibitor: Lowers blood pressure.
  • Beta blocker: Slows heart rate, lowers blood pressure.
  • Antiarrhythmic agent: Controls irregular or other abnormal heart rhythms.

Your doctor will look for signs of irritation of the heart muscle during a physical exam and also review your medical history.


Blood test: Can reveal signs of infection or inflammation.

X-ray: To check for signs of heart failure.

Electrocardiogram (EKG): A check for damaged heart muscle or abnormal heart rhythms.

Ultrasound (echocardiogram): Can detect an enlarged heart.


What can you do to prevent myocarditis? Avoid serious infections.

Here are a few ways:

  • Proper hygiene.
  • Low-sodium diet (no more than 1,500 to 2,400 milligrams a day).
  • Practicing safe sex.
  • Avoiding ticks.
  • Get all scheduled vaccinations.