Myocarditis is a rare cardiovascular issue involving inflammation of the heart muscle, usually due to a viral infection. While rare, it can also develop following an adverse drug reaction. In recent years, there has been a minor increase in the number of cases of myocarditis due to reactions to certain COVID-19 vaccines.

Doctors can diagnose myocarditis using imaging tests that reveal the inflammation or by doing a heart biopsy. Treatment is reliant on the type and severity of myocarditis and may involve corticosteroids, heart medications, or breathing therapies.

Myocarditis can vary in severity, causing a range of issues from more minor, like shortness of breath and fatigue, to severe, such as heart failure or even sudden death.

Chest Pain

Most people with myocarditis experience some level of chest pain, which they often describe as sharp or stabbing in nature. Some individuals also report having pain in the arm, shoulder, upper chest, or jaw.

The pain may initially worsen with exertion or exercise. As the inflammation progresses, flare-ups may occur even while resting.

woman experiencing chest pain Povozniuk / Getty Images


Shortness of Breath

Like many cardiac conditions, myocarditis can cause shortness of breath. Depending on the individual and the severity of their condition, shortness of breath causes different levels of distress and discomfort.

Usually, it feels as if breathing takes more effort along with the distinct sensation of not receiving enough air. With myocarditis specifically, shortness of breath worsens when lying down.

man lying down experiencing shortness of breath


Palpitations and Arrhythmias

Many people with myocarditis become more sensitive to and aware of cardiac muscle contractions in their chests. They often feel as if their heartbeats are too fast, intense, or irregular. Despite how they feel, these palpitations do not necessarily indicate any heartbeat irregularities.

However, in certain circumstances, myocarditis can also affect heartbeats and cause arrhythmias.

A woman who feels palpitations in her chest


Dizziness or Fainting

Children and young adults are particularly prone to dizziness and fainting, though it can affect people of any age. In some cases, these symptoms reflect inadequate blood flow to the brain.

If a person with myocarditis faints, they should seek medical attention. Individuals with dizziness will often also experience chest pain, shortness of breath, and palpitations.

man feeling dizzy or headache Phynart Studio / Getty Images



People with myocarditis sometimes develop fevers, especially when the source is infectious, such as parvovirus B19. A fever may indicate a more serious case of myocarditis that requires more rigorous treatment.

It is worth noting that children usually have more severe cases of myocarditis and are more likely to have fevers as a result.

woman lying in bed with fever VioletaStoimenova / Getty Images



Because it affects so many of the body’s systems and often originates from a viral infection, myocarditis can cause people to tire more easily. They may also have a general feeling of fatigue and lack of energy, which interferes with day-to-day activities.

Because this symptom often occurs alongside others consistent with viral infections, it can be difficult to diagnose myocarditis without further testing.

employee falls asleep seated on chair at workplace fizkes / Getty Images


Swollen Feet and Legs

Especially if it has a viral origin, myocarditis may present with fluid retention and swelling of the legs, ankles, and feet. Usually, this occurs alongside other signs of an infection, like fever or tiredness. In some cases, ankle swelling indicates a severe case of myocarditis that could lead to heart failure.

woman's feet swelling Darya Komarova / Getty Images


Other Signs of Infection

Myocarditis may also cause or occur alongside other common signs of an infection, such as sore throat, headache, muscle aches, and diarrhea. These symptoms often appear several days before other signs and resemble a flu-like illness.

Signs of infection often clear up within a few days, but they may persist until a person receives treatment for their myocarditis.

man suffering a sore throat Moyo Studio / Getty Images


Other Breathing Issues

Later stages of myocarditis often involve more respiratory issues. Difficulty breathing, called respiratory distress, regularly develops. Signs of respiratory distress include nose flaring, skin color changes, sweating, grunting while breathing, and wheezing.

In many cases, doctors initially mistake these for symptoms of asthma or pneumonia.

woman wiping her sweat LENblR / Getty Images


Dull Heart Sounds

When listening to the heart of someone with myocarditis, the rhythm may sound dull or “muffled.” This occurs because inflammation of the heart muscle limits the volume of the heartbeat.

The phenomenon is particularly common when myocarditis occurs at the same time as pericarditis, a similar condition involving inflammation of the fibrous sac around the heart.

Closeup shot of a doctor examining a patient with a stethoscope Charday Penn / Getty Images


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