Infective endocarditis

Infective endocarditis is an infection of the inner lining or valves of the heart. It is caused by bacteria, or sometimes fungi, entering the bloodstream and sticking to heart structures.

It is quite rare, affecting 30 in a million people each year. It can be serious, particularly if there are complications, so early diagnosis and treatment are vital.

Treatment is a course of antibiotics given through an IV drip (a small tube into your vein) given while you stay in hospital. Up to half of people affected need surgery to repair or replace a damaged heart valve.

Even with the highest standards of medical care, 1 in 5 people are at risk of dying from infective endocarditis.

Causes of infective endocarditis

Symptoms of infective endocarditis

Diagnosing infective endocarditis

Treatment for infective endocarditis

Recovery after treatment

Support and more information

Causes of infective endocarditis

Your heart is usually well protected against infection, and most bacteria pass harmlessly. However, if your heart valves are damaged, or you have an artificial valve, it is easier for bacteria to get past your immune defence and cause problems.

This can mean that bacteria settle on the inner lining of your heart (endocardium). These organisms are sometimes referred to as vegetations. They cause inflammation (swelling) of the endocardium, and that can damage your heart valves.

Clumps of cells form around the bacteria or fungi, which can break off and, sometimes, cause conditions such as stroke.

Ways of bacteria entering your bloodstream

  • Through the mouth during everyday activities like brushing teeth or chewing food. This is more likely if teeth and gums are in bad condition or decayed.
  • Through needles and tubes (for example, when you're receiving haemodialysis or chemotherapy).
  • Bacteria in your gut can sometimes enter the bloodstream through ulcers or tumours in your bowel.
  • Bacteria can be introduced during heart surgery or when a pacemaker is put in.
  • Urinary (pee) catheters can introduce infection into the blood through the bladder.

Increased risk of getting infective endocarditits

You are more likely to get infective endocarditis if you have:

  • had infective endocarditis before
  • a prosthetic (artificial) or repaired heart valve
  • some types of congenital heart disease (heart defects from birth)
  • thickened or leaking heart valves (including bicuspid aortic valve)
  • enlarged heart muscles and thickened walls (hypertrophic cardiomyopathy)
  • have tubes (cannulas) in your veins for cancer treatment or dialysis
  • medical conditions that lower your immunity to infection, such as HIV and diabetes
  • injected non-prescription drugs intravenously (into a vein)
  • some invasive dental procedures, like extractions or deep scaling

Symptoms of infective endocarditis

Symptoms can develop quickly in days, or slowly over weeks. It is vital to get medical attention at the earliest signs, so that you can have blood tests to try and identify the cause.

The most common symptoms of endocarditis include:

  • unexplained flu-like symptoms (high temperature or fever, sweats, chills) that are severe or last longer than a week
  • weight loss, poor appetite
  • general fatigue and feeling unwell
  • new back pain

Without early treatment you can have complications. These include:

  • confusion or drowsiness
  • shortness of breath from severe valve damage
  • stroke
  • ‘cold leg’ from a blocked artery
  • boils or black patches on the toes or fingers

Diagnosing infective endocarditis

The diagnosis is made by assessing your symptoms, and by doing blood tests (including blood cultures) and an echocardiogram (ultrasound scanning of the heart) in hospital.

You will need to be admitted to hospital to confirm the diagnosis, and you'll be given a course of antibiotics through a thin tube (cannula) into a vein (intravenously) in your arm.

Contact your GP if:

you have unexplained flu-like symptoms that are severe or last longer than a week:

  • high temperature (fever)
  • sweats
  • chills

When you visit your GP:

  • you should tell them that you are in a higher-risk category for infective endocarditis (they might be trained to think of more common conditions first)
  • they should arrange for blood tests, including blood cultures (to identify the bacteria), before starting antibiotics for an unknown infection (this is very important because antibiotics might affect your test results)
  • if they suspect infective endocarditis, they will probably arrange a hospital visit, because tests are done there more easily 

Call 999 for an ambulance immediately if:

  • you suspect stroke, even if you do not have any symptoms of endocarditis

Take your infective endocarditis alert card with you.

Stroke is one of the most serious complications of endocarditis.

The best way to identify the symptoms of stroke is to remember the word FAST, which stands for:

  • Face. Their face might have fallen on 1 side, they might not be able to smile, or their mouth or eye might have drooped.
  • Arms. They might be unable to raise both arms and keep them up, as a result of weakness or numbness.
  • Speech. Their speech might be slurred.
  • Time. It is time to call 999 immediately if there are any of these signs or symptoms.

Treatment for infective endocarditis

If endocarditis is a possibility, antibiotics should not be started before tests have been done, unless you are very unwell.


At first, all cases of infective endocarditis need to be treated in hospital with high-dose antibiotics given through an IV drip, usually into your arm.

Blood samples will be taken to see how well the treatment is working.

You will be under the care of a heart specialist, with input from an infection specialist and sometimes a heart surgeon. They will form the endocarditis team, and will discuss your case at regular meetings.

Depending on how bad your condition is, you will usually need antibiotics through a drip for 2 to 6 weeks. You might need to continue antibiotics orally (by mouth) for several weeks after this, especially if there are complications, such as a bone infection.

Sometimes it is possible to finish a course of IV antibiotics at home. They might be given by a family member or a district nurse, or you might be able to do it yourself.

You will usually need to return to hospital every week to be checked.


Surgery will usually be recommended if:

  • there is serious valve damage and a risk of heart failure
  • the infection does not settle with just antibiotics 
  • there is an abscess in the heart
  • infected tissue breaks off the valve and moves round the body even though you have had antibiotics

Surgery involves the repair or replacement of the damaged heart valve. If there is an abscess near your heart valve, it might be necessary to replace part of the main artery (aorta) as well. This is done using an artificial or biological graft.

Surgery for endocarditis can be complex and has risks, particularly because anyone who needs this surgery is usually very ill to start with.

IV antibiotics will be continued after surgery until your team are satisfied that you have no signs of infection.

Recovery after treatment

Infective endocarditis is a major illness and it is normal to feel weak for several weeks afterwards, even if you have had no complications.


You should find ways to remember to take your medicines at the right time and at the right dose. You might choose to put a reminder on your phone, keep a diary, or use a dosette box (small box with compartments that show which pills need to be taken, and when).

Physical and emotional wellbeing

Before you received treatment, you might have been physically very unwell.

If you had surgery, you will be seen by the cardiac rehabilitation team to help you cope with pain and discomfort afterwards. You might have difficulty with your concentration or memory, or emotional problems for weeks or months.

Although not all people are affected in the same way, you might feel worried, depressed, guilty, ashamed or angry. If you are feeling any of these emotions, please speak to your GP.

Returning to normal activities

You will not be able to do very much while you feel physically and emotionally weakened. However, you should consider returning to your usual activities as soon as you feel physically able.

Not doing your normal activities for a long time, and perhaps being stuck in bed, can lead to problems (such as severe tiredness (fatigue) and muscle weakness) when you start to move around again.

Gradually increasing physical activity can be a good treatment for negative feelings, and you should not 'put your life on hold' as it will not help your recovery.

You should try to have a good diet and sleep routine, and make time for enjoyable things, like hobbies and socialising. This will create a positive cycle of improvement.

Being too inactive, and activities like smoking or drinking too much alcohol or caffeine, can have negative effects on your physical wellbeing even though they might seem to help in the short term.

Read our information about recovering from surgery.

Follow-up appointments

You will be seen as an outpatient by the heart team 4 to 6 weeks after leaving hospital.

Unfortunately, you have an increased risk of developing endocarditis again in the future, but there are other ways to reduce the risk of infective endocarditis. The most important is to look after your teeth.

Support and more information

Endocarditis on the NHS website

British Heart Foundation      

British Heart Valve Society

Heart Valve Voice

Information about taking anticoagulants or antiplatelet medicines, from NHS Scotland

Resource number: 4802/VER2
Last reviewed: December 2023
Next review due: December 2026

Contact us

The heart valve service's infective endocarditis team can be contacted,
phone: 020 7188 1047
email: [email protected]

Do you have any comments or concerns about your care?

Contact our Patient Advice and Liaison Service (PALS)

Is this health information page useful?