Innocent heart murmur - parental information

What is a heart murmur?

There are normally two sounds made by a heart. A heart murmur is an extra noise heard along with or in between the heart sounds. When we listen with a stethoscope, they often make a ‘whooshing’ or ‘swishing’ sound. 

What causes a heart murmur?

A murmur is heard when there is extra flow of blood across the heart or the blood vessels attached to the heart. This can be because of an abnormality (difference) in the structure of the heart, such as a hole between the pumping chambers or a valve abnormality. It can also happen when there is an increased blood flow across a normal heart. 

What is an innocent heart murmur?

A murmur is called ‘innocent’ when heard in an otherwise normal heart. It is very common in babies and young children.

What causes an innocent heart murmur?

This can happen due to blood flowing through the large veins of the heart or from the flow of blood around the bends of the normal heart. 

How can you tell the difference between innocent murmurs and abnormal murmurs?

Children with innocent murmurs have no symptoms of heart problems such as poor growth, breathlessness, turning blue or grey - on brown or black skin or fainting. Innocent murmurs sound soft. They can be heard sometimes and not others, and tend to become louder when their heart beats faster e.g. during an episode of illness or excitement. 

Should I be worried?

Innocent murmurs are often heard in babies and young children and may disappear over time. Sometimes, they can continue into adulthood, although this is rare. They do not cause problems as the heart structure is normal. No further investigations or treatment is required and children do not need long term follow up. The presence of innocent murmur does not have any long term health effects. No extra precautions are needed for travel or exercise.

Innocent heart murmur - parental information leaflet
Date of review: October 2023
Date of next review: May 2026