Patient Information Fact Sheets

Innocent (Benign) Heart Murmurs

What is a heart murmur?

A heart murmur is a sound heard when a doctor listens to the heart with a stethoscope. Instead of the usual “lub-dub” heartbeat, there may be an extra whooshing or swishing sound caused by blood flowing through the heart. Murmurs are quite common, especially in children, and most are harmless.

What is an innocent murmur?

An innocent murmur (also called a benign or functional murmur) is a heart murmur that occurs in a completely normal heart. It simply reflects normal blood flow through the heart and blood vessels.

Innocent murmurs:

  • Are not caused by heart disease

  • Do not damage the heart

  • Do not require treatment

  • Do not restrict normal activities

Many healthy children — and some adults — have innocent murmurs.

Why do innocent murmurs occur?

Innocent murmurs happen because blood is flowing a little faster or more turbulently than usual through a normal heart.

They may be easier to hear when:

  • A child is growing rapidly

  • Someone has a fever

  • After exercise

  • During pregnancy

  • If a person is thin or has a flexible chest wall

In children, they often become quieter or disappear as the child grows.

Are innocent murmurs common?

Yes. Innocent murmurs are very common in childhood. About 50–70% of children will have a murmur heard at some stage, and most of these are innocent.

How do doctors know a murmur is innocent?

Doctors assess murmurs by:

  • Listening carefully with a stethoscope

  • Checking the child’s growth and symptoms

  • Performing a physical examination

Innocent murmurs typically:

  • Are soft

  • Occur during heart contraction (systole)

  • Change with body position

  • Occur in children who are otherwise completely well

If there is any uncertainty, further tests such as an echocardiogram (heart ultrasound) may be recommended.

Symptoms to watch for

Children or adults with innocent murmurs do not have symptoms related to the murmur. If any of the following occur, medical review is recommended:

  • Shortness of breath

  • Chest pain

  • Fainting

  • Poor growth or feeding in infants

  • Blue lips or skin

  • Exercise intolerance

These symptoms are not typical of innocent murmurs.

Do innocent murmurs need treatment?

No. Innocent murmurs:

  • Do not need medication

  • Do not need surgery

  • Do not require antibiotics before dental procedures

  • Do not limit sports or physical activity

People with innocent murmurs can live normal, healthy lives.

Do innocent murmurs go away?

Many innocent murmurs disappear as children grow older, although some can persist into adulthood without causing any problems.

When should I see a doctor?

You should seek medical advice if:

  • A murmur is newly detected

  • Symptoms develop

  • You have concerns about your child’s heart

Your doctor can determine whether the murmur is innocent or requires further evaluation.