Find Information About:

Drugs & Supplements

Get information and reviews on prescription drugs, over-the-counter medications, vitamins, and supplements. Search by name or medical condition.

Pill Identifier

Pill Identifier

Having trouble identifying your pills?

Enter the shape, color, or imprint of your prescription or OTC drug. Our pill identification tool will display pictures that you can compare to your pill.

Get Started

My Medicine

Save your medicine, check interactions, sign up for FDA alerts, create family profiles and more.

Get Started

WebMD Health Experts and Community

Talk to health experts and other people like you in WebMD's Communities. It's a safe forum where you can create or participate in support groups and discussions about health topics that interest you.

  • Second Opinion

    Second Opinion

    Read expert perspectives on popular health topics.

  • Community


    Connect with people like you, and get expert guidance on living a healthy life.

Got a health question? Get answers provided by leading organizations, doctors, and experts.

Get Answers

Sign up to receive WebMD's award-winning content delivered to your inbox.

Sign Up

Heart Disease Health Center

Font Size


Affecting several thousand Americans each year, myocarditis is a disease marked by inflammation of the heart muscle (myocardium). Exactly how many people are affected is hard to know because myocarditis often produces no symptoms.

A wide range of infections and other problems can lead to myocarditis, which often develops in people who are otherwise healthy. Prevention or prompt treatment of infections is one of the best ways to prevent myocarditis.

Recommended Related to Heart Disease

Mitral Valve Prolapse Syndrome

Important It is possible that the main title of the report Mitral Valve Prolapse Syndrome is not the name you expected. Please check the synonyms listing to find the alternate name(s) and disorder subdivision(s) covered by this report.

Read the Mitral Valve Prolapse Syndrome article > >

Causes of Myocarditis

Viral infection is the most common cause of myocarditis.

When you have an infection, your body produces cells to fight infection. These cells also release chemicals. If the disease-fighting cells enter your heart, they can release chemicals that can damage your heart muscle. Your heart may become thick, swollen, and weak. Seeking immediate medical care for infections can help prevent complications.

These are some of the types of infections that can cause myocarditis.

Viral infections

Bacterial infections

Fungal and parasitic infections can also cause myocarditis.

Other causes of myocarditis include certain chemicals or allergic reactions to medications or toxins such as alcohol, drugs, lead, spider bites, wasp stings, or snakebites and chemotherapy and radiation therapy. Having an autoimmune disease such as lupus or rheumatoid arthritis that causes inflammation throughout your body may also lead to myocarditis.

Signs and Symptoms of Myocarditis

Myocarditis often has no symptoms. In fact, most people recover and never even know they had it.

If you do have symptoms, they may include one or more of these:

  • Shortness of breath during exercise at first, then at night while lying down
  • Abnormal heartbeat, which causes fainting in rare cases
  • Light-headedness
  • An often sharp or stabbing chest pain or pressure, which may spread to neck and shoulders
  • Fatigue
  • Signs of infection, such as fever, muscle aches, sore throat, headache, or diarrhea
  • Painful joints
  • Swollen joints, legs, or neck veins
  • Small amounts of urine
1 | 2 | 3

Today on WebMD

x-ray of human heart
A visual guide.
atrial fibrillation
Symptoms and causes.
heart rate graph
10 things to never do.
heart rate
Get the facts.
empty football helmet
red wine
eating blueberries
Simple Steps to Lower Cholesterol
Inside A Heart Attack
Omega 3 Sources
Salt Shockers
lowering blood pressure