About 80 percent of all children have a heart murmur at some time. Most heart murmurs don't mean there is anything wrong. A normal murmur is just a noise caused by blood flowing through a normal heart. A normal murmur can get louder when the blood flows faster through the heart. For example, when the body's temperature goes up, the blood flows faster.
Doctors often hear heart murmurs when they check children who have a fever.
Many normal murmurs become hard to hear as children grow older. Some murmurs just go away. If your child has a normal heart murmur, he or she can run, jump and play, with no limits on activity. Your child doesn't need to take any medicine or be careful in any special way. Sometimes a heart problem causes a murmur.