Heart murmurs - causes, symptoms & treatment

What is a heart murmur?

A heart murmur is an extra, unusual sound in your heartbeat – sometimes described as a whooshing or swishing noise. This can be heard when the doctor listens to your heartbeat through a stethoscope. The extra noise happens when your blood does not flow smoothly through your heart. 

Most heart murmurs are harmless. But if your doctor hears something unusual, they might send you for tests to see how well your heart is working. 

What are the signs and symptoms of a heart murmur? 

Many people with a heart murmur do not feel any symptoms. But depending on what is causing the murmur, you may have symptoms like: 

• fainting
• dizziness
• chest pain 
• shortness of breath 
• swelling in your legs, arms or tummy area 
• a continuous cough that does not seem to be getting better 
• sweating a lot when you’re resting or doing minimal activity 
• lack of appetite (in babies and children only). 

If you experience symptoms, visit your local GP. Your doctor can listen to your heart with a stethoscope and refer you to have tests or treatment with a specialist if needed. They can also support you if you feel worried or concerned. 

You should call 999 immediately if you're experiencing:

• pain in your chest or upper body
• difficulty breathing or shortness of breath.

Is a heart murmur dangerous? 

Most heart murmurs are not dangerous. But sometimes they can be a sign of a problem with your heart. Heart murmurs are classed as either: 

Innocent heart murmur – when your heart still beats normally but makes extra sounds when your blood flows through your heart faster than usual. Innocent murmurs are harmless. They are common in babies, young people and adults. They can come and go or happen regularly throughout your life. 

Abnormal heart murmur – is when the extra sounds in your heartbeat are caused by a problem with your heart. This can be dangerous if it’s left untreated, but this is not common. Abnormal heart murmurs are rare, especially in babies or young people. If your doctor thinks you might have an abnormal heart murmur, they will arrange tests to see how your heart is working.

If your healthcare team diagnoses a problem with your heart, they will discuss treatment options with you. Your healthcare team will understand if you feel worried and can support you. 

Innocent heart murmurs in children

It’s common for babies and children to experience ‘innocent’ heart murmurs. They usually disappear by the time they reach puberty (between the ages of 8-14) and do not need any treatment.

Your child might have harmless murmurs come and go depending on their breathing, their heart rate and how active they’re being at the time.

What are the types of heart murmurs?

There are three main types of heart murmurs, based on when they happen during your heartbeat: 

• systolic murmur – happens when the heart contracts to pump blood to the rest of your body
• diastolic murmur – happens when the heart relaxes between beats to fill up with blood
• continuous murmur – is heard throughout the heartbeat, both when the heart contracts and relaxes.

Each type can sound different and may point to different causes. Your doctor will decide after listening to your heart, if further tests are needed.

What causes a heart murmur?

Innocent heart murmurs can be heard when blood flows through your heart faster than usual. This can be caused by: 

• an overactive thyroid (a small butterfly-shaped gland in the neck) 
• sudden growth (in babies and young people) 
• exercise or physical activity that raises your heart rate 
• pregnancy (your body makes and pumps extra blood for your baby) 
• having a fever (a raised temperature makes your heart pump blood faster) 
• anaemia (when you do not have enough healthy red blood cells to carry a normal amount of oxygen around your body). 

Abnormal heart murmurs are caused by a problem with your heart. The problem could be: 

• An infection – sometimes bad bacteria can infect your heart muscle and cause conditions like rheumatic fever. 
• A congenital heart condition – structural problems with the heart which develop when a baby is in the womb. 
• Heart valve disease – a problem with your heart valves could interrupt the normal blood flow. 

How is a heart murmur diagnosed? 

Your doctor will listen to your heart with a stethoscope to see if you have a heart murmur. If they think it could be an abnormal heart murmur, your healthcare team may arrange tests to find out what is causing the murmur.

The tests may include: 

• A Chest X-ray – to see if your heart muscle looks bigger than it should be. 
• An ECG (electrocardiogram) - to check the rhythm, rate and electrical activity of your heart. 
• An echocardiogram – an ultrasound of your heart to see if there’s a problem with the structure of your heart or your heart valves. 

These tests are very common, but you can speak to your doctor if you feel worried about having them. 

Will my heart murmur need treatment? 

Innocent heart murmurs do not usually need treatment. But if your murmur is caused by a problem with your heart or another condition, then the cause of the murmur may need treatment. 

There are many treatments for underlying heart conditions and your doctor will tell you if you need treatment. They will discuss the options, answer your questions and create a plan to treat and manage your heart murmur with you. 

Treatments might be recommended to help you manage the symptoms of your heart murmur even if you do not have an underlying heart condition. 

Get support

Having a heart murmur or an underlying problem with your heart can be worrying. Your local GP service and healthcare team are there to help you.

But if you’re feeling concerned and would like emotional support, our cardiac nurses can help you too. You can contact our Heart Helpline nurses by phone or email. Or you can connect with other people in a similar situation to you on our online HealthUnlocked community.