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Written by Ada’s Medical Knowledge Team

Updated on

What is endocarditis?

Endocarditis is a rare infection of the inner lining of the heart (endocardium) and the heart valves, usually caused by germs (or, less commonly, fungus) entering the bloodstream and passing into the heart.[1] However, a rare, non-infective variant also exists. Non-infective endocarditis is a build-up of clots on the endocardium or cardiac valves, caused by certain medical conditions, including some types of cancer, pregnancy and trauma.[2]

Endocarditis treatment will usually involve a course of antibiotics and – in rare cases, usually when complications arise – surgery. If left untreated, the condition can cause severe damage to the heart and result in life-threatening complications. Early diagnosis is critical to improving the prognosis of those with endocarditis.[3]

Symptoms of endocarditis

Symptoms of endocarditis may include:[4]

  • Fever and chills
  • Fatigue and night sweats
  • Loss of appetite
  • Weight loss
  • Generally feeling unwell
  • Pain in the muscles or joints
  • Shortness of breath and coughing
  • Chest pain when breathing
  • Swelling of the legs, ankles or feet

Less common symptoms may include:

  • Blood in the urine
  • Tenderness in the upper half of the abdomen
  • Red spots on the hands or feet
  • Red-purple bumps under the skin of the toes or fingers (Osler’s nodes)
  • Small red or purple spots on the skin, inside the mouth or on the whites of the eyes
  • Back pain

Non-infective endocarditis will generally present fewer symptoms than infective endocarditis and they are unlikely to develop until the later stages of the condition or when complications arise. Symptoms of infective endocarditis can either develop slowly or rapidly (in a number of days) depending on what kind of bacteria or fungi is causing the condition.

Complications can develop quickly, making the condition more difficult to treat. For this reason, it is important to see a doctor early when worrying symptoms occur. If you are experiencing symptoms or feel unwell, you can use the free Ada app to do a symptom assessment at any time.

Causes of endocarditis

Endocarditis most often occurs in people with preexisting heart disease (which may be diagnosed or undiagnosed) and less commonly in people with normal hearts.

Endocarditis may occur when bacteria or fungi enter the bloodstream through small injuries (such as those experienced during teeth cleaning), when injecting into the veins, during surgery, or as a result of other infections. If the bacteria or fungi reach the heart, they may settle on the endocardium (the heart’s inner lining or valves) and begin to grow – causing an infection.

Ordinarily, the immune system is able to clear bacteria and fungi that enter the bloodstream. When this does not happen, however, some bacteria or fungi can settle on the endocardium or valves of the heart (especially likely if a valve is already damaged in some way) and form small growths (vegetations). These growths can prevent the heart from functioning correctly and may break off and infect other areas of the body.

While endocarditis is a rare condition, the following groups are most at risk:[5]

  • People with previously damaged heart valves or an artificial heart valve
  • Users of injected drugs such as heroin

It should also be noted that any procedure that requires placing medical devices into the veins or any type of heart surgery can also be a risk factor.

Those most at risk of non-infective endocarditis include people with the following conditions:[6]

If you are feeling unwell, you can do a free symptom assessment with the Ada app at any time.

Diagnosing endocarditis

If a diagnosis of endocarditis is suspected based on the symptoms and medical history, a thorough physical examination will be carried out, paying particular attention to the heart.[7] In particular, doctor’s will listen for heart murmurs (unusual sounds from the heart), which can be an indicator of the condition. A doctor will in most cases then also order a series of tests to confirm the diagnosis.

Blood tests will be ordered in order to identify any bacteria or fungi present in the blood. An ultrasound of the heart may also be able to show signs of any abnormal growths on the heart valve, as well as any damage to the heart. Further diagnostic tests (X rays, CT scan, MRI, ECG) can also be carried out to investigate any involvement in other organs .[8]

If blood tests reveal no sign of infection but other symptoms and risk factors are present, the diagnosis of non-infective endocarditis may still be possible.[9]

Endocarditis treatment

Many cases of (infective) endocarditis can be effectively treated with antibiotics or antifungal medication. If the growth is very large, or if there is new or pre-existing damage to the heart, surgery may be required.[10]


As soon as possible after diagnosis, an individual with infective endocarditis will be treated with antibiotics, usually intravenously (through a drip). The course will last for several weeks, a period through which most people will be required to stay in hospital.

If an individual continues to feel unwell after a number of days of treatment using antibiotics, or if new symptoms occur, it is important to inform a doctor.


If the endocarditis causes severe damage to the heart, or infections are persistent, surgery may be necessary. The goal is generally repair a damaged valve or replace a valve entirely. Surgery can be life-saving, but it is a risky procedure with possible complications.

Treating non-infective endocarditis

Treatment for non-infective endocarditis generally involves treating the underlying condition that is its cause. Drugs to prevent the formation of new blood clots may be prescribed, but this will depend on the doctor and the underlying causes of the condition.[11]

Endocarditis complications

Complications will generally arise if endocarditis is left untreated or if it is treated too late.

The two most serious complications of endocarditis are heart failure and sepsis. If growths in the heart break up and spread to other areas of the body, complications including abscesses, strokes and – in some cases – seizures are possible. Heart failure, sepsis and seizures are all medical emergencies and if they occur, the affected person should receive medical assistance as soon as possible.

Endocarditis prevention

To help prevent endocarditis, it is important – especially for those who are particularly vulnerable to the disorder – to be aware of its signs and symptoms. Through this awareness, if any signs or symptoms occur, it will be possible to seek medical assistance without delay.

It is also important to maintain high standards of dental hygiene and to receive regular checkups from a dentist. This will help prevent any bacteria from the mouth passing into the bloodstream. Individuals should also avoid getting tattoos and piercings – activities that can lead to infection.

People with a known high risk of developing endocarditis may also be given preventative antibiotics before dental or medical procedures. This decision, however, is left to the discretion of the doctor or dentist.[12]

Users of injected drugs (such as heroin) should use only sterile syringes, needles and other apparatus, and never share syringes with others in order to reduce the risk of infection.

Endocarditis prognosis

Early diagnosis and treatment can improve the prognosis for endocarditis, with many people recovering after receiving appropriate treatment. If left untreated, however, the condition often becomes life-threatening. Older people, those with a particularly resistant infection, those with particularly large growths and those with underlying medical conditions have a higher probability of experiencing complications as a result of the condition.[13]

The prognosis for those with non-infective endocarditis is dependent on the underlying medical condition that is the cause of the condition.[14]

Endocarditis FAQs

Q: What is the prognosis for endocarditis?
A: The prognosis for endocarditis can be significantly improved if the condition is detected early and treatment begun quickly. If left untreated, the condition can be life-threatening. In cases of non-infective endocarditis, the prognosis depends on the severity of the symptoms and the cause of the condition.

Q: When should I seek medical attention for suspected endocarditis?
A: People who have an ongoing fever, chills and shortness of breath, or who have any other worrisome symptoms, should see a doctor for review of these symptoms. Those at higher risk of the condition (people with a damaged heart, those who have had a valve repair or replacement or injected drug users) should make themselves aware of the symptoms and see a doctor as soon as any of these they occur.

Q: Can I receive preventative treatment for endocarditis?
A: People at high risk of contracting endocarditis may be given preventative treatment, which will usually take the form of antibiotics to help the body combat a possible infection. People with a damaged heart, heart disease and users of injected drugs should consult a doctor about the possibility of using preventive treatment methods. A doctor will be able to assess the probability of endocarditis and explain the options from there. Preventative measures may be particularly important before surgical and dental procedures.[15]

  1. HealthHype. “Endocarditis (Infective and Noninfective) Causes and Symptoms” Accessed August 18, 2017.

  2. News Medical. “Non-Infective Endocarditis.” Accessed August 18, 2017.

  3. NHS Choices. “Endocarditis.” March 24, 2016. Accessed August 18, 2017.

  4. Mayo Clinic. “Endocarditis - Symptoms and causes.” July 15, 2017. Accessed August 18, 2017.

  5. Patient. “How does endocarditis occur and progress?” August 1, 2017. Accessed August 18, 2017.

  6. MSD Manual. “Noninfective Endocarditis.” Accessed August 18, 2017.

  7. NHS Choices. “Endocarditis - Diagnosis.” March 24, 2016. Accessed August 18, 2017.

  8. Mayo Clinic. “Endocarditis - Diagnosis.” July 15, 2017. Accessed August 18, 2017.

  9. MSD Manual. “Noninfective Endocarditis.” Accessed August 18, 2017.

  10. Mayo Clinic. “Endocarditis - Treatment.” July 15, 2017. Accessed August 18, 2017.

  11. MSD Manual. “Noninfective Endocarditis.” Accessed August 18, 2017.

  12. Mayo Clinic. “Endocarditis - Self-management.” July 15, 2017. Accessed August 18, 2017.

  13. MSD Manual. “Infective Endocarditis.” Accessed August 21, 2017.

  14. MSD Manual. “Noninfective Endocarditis.” Accessed August 21, 2017.

  15. Patient. “Prevention of Infective Endocarditis.” September 22, 2015. Accessed September 8, 2017.

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