Understanding Common Pediatric Heart Murmurs in Children

When a Heartbeat Isn't Just a Lub-Dub

Hearing that your child has a heart murmur can feel worrying, but most murmurs in children are harmless. In fact, many are innocent heart murmurs that may come and go as your child grows, requiring no treatment at all.

While an innocent murmur is a normal sound of blood flowing through the heart, a pathological murmur may signal an underlying heart condition that needs attention. Distinguishing between the two is exactly what a pediatric cardiology evaluation is designed to do, and it's often far simpler than parents expect.

What an Evaluation Involves

A thorough exam at a pediatric cardiology visit typically begins with a detailed history and a focused physical exam, listening carefully to the murmur's timing and sound. If more information is needed, painless, noninvasive tests like an echocardiogram (ultrasound of the heart) can give a clear picture of heart structure and function. Most children find the process quick and stress-free.

For most children, the result is reassurance that their murmur is innocent. For a small number, the evaluation identifies a specific issue that may benefit from monitoring or treatment, allowing you to plan care with accurate information.

What Is a Heart Murmur and What Causes It?

A heart murmur is an extra whooshing or swishing sound that a doctor hears between the normal "lub-dub" of the heartbeat. That familiar lub-dub comes from the valves closing as blood moves through the heart. A murmur happens when blood flows through the heart with turbulence, meaning the flow is not smooth and silent. Think of water moving through a garden hose: when the hose is kinked or the water meets an obstacle, it makes a rushing noise. The heart works the same way, and a stethoscope picks up that extra sound.

In children, most heart murmurs are "innocent" or functional. These innocent heart murmurs are harmless sounds made by normal blood flow, often more audible in children because their chests are thin and their hearts beat faster. Innocent murmurs tend to come and go, they may change with position or breathing, and importantly, they are not linked to any structural problem. A child with an innocent murmur can run, play, and exercise without restriction, and the murmur often disappears on its own by the teenage years.

Pathological murmurs are different. These are caused by an actual structural issue, such as a hole in the heart, a narrowed valve, or an abnormal connection between heart chambers. Unlike innocent murmurs, pathological ones usually produce additional signs like poor feeding, rapid breathing, or a bluish tint to the skin. Doctors can often tell the difference by listening carefully to the murmur's timing, pitch, and location, and when there is any doubt, they recommend an echocardiogram to get a clear picture. This is one reason why evaluation of a heart murmur matters: what sounds similar to a parent can be very different to a pediatric cardiologist.

So What Actually Causes the Turbulence?

Several everyday factors can make blood flow through a child's heart sound turbulent. A faster heart rate from fever, exercise, or excitement increases the blood's speed and can produce a murmur. Anemia, which lowers the blood's oxygen-carrying capacity, makes the heart pump harder and faster, and that extra effort can also create a murmur. Even normal growth can be responsible: as a child grows, the heart's chambers and valves change size, and the angle at which blood hits the walls changes too. These are all situations where the murmur is a symptom of normal physiology, not of disease.

Structural causes are less common but more serious. A ventricular septal defect, or a hole between the lower chambers, is the most frequent congenital heart problem that produces a murmur. A patent ductus arteriosus, an open blood vessel that should close shortly after birth, creates a continuous murmur. Narrowed valves, such as pulmonary stenosis, force blood through a tight opening and produce a characteristic sound. For parents, the important takeaway is not to diagnose the cause at home but to recognize when a murmur deserves a closer look. Persistent symptoms like cyanosis, rapid breathing, or poor feeding are the kinds of red flags that signal a visit to a specialist.

Innocent vs. Pathological: Why the Distinction Matters

The difference between an innocent and a pathological murmur is not just a matter of labeling. It determines whether a child needs no follow-up, a repeat exam in a few months, or a referral to a pediatric cardiologist. For innocent murmurs, the American Academy of Family Physicians advises that most children need no further testing and can live fully normal lives. Pathological murmurs, by contrast, often require an echocardiogram and possibly treatment, so getting an accurate diagnosis is the whole game. Parents who understand this distinction are better equipped to ask the right questions at the pediatrician's office and to know when a second opinion makes sense.

For many families, the most valuable step is a thorough evaluation by a pediatrician who can tell the two apart through careful listening and, when needed, an echocardiogram. At Federal Way Pediatrics, we focus on identifying innocent murmurs quickly so parents can stop worrying, and on referring children with suspicious findings to pediatric cardiology before problems advance. This approach gives families clarity, and it means most children never need to see a specialist at all — but when they do, the path is already clear.

Distinguishing Innocent From Pathologic Murmurs

A heart murmur is the sound of turbulent blood flow inside the heart, heard as a whooshing or swishing noise between the normal "lub-dub" beats. In children, murmurs are extremely common, and most are completely harmless. These are called innocent or functional murmurs, and they simply reflect normal blood flow through a healthy heart. They affect up to 72% of children at some point, with many children experiencing them at various ages.

For context, the American Academy of Family Physicians notes that up to 72% of children will have a heart murmur at some point, and the vast majority are innocent. Innocent murmurs are more common in newborns and children, often disappearing as the child grows. They typically cause no symptoms and require no treatment.

Innocent Heart Murmurs

Innocent murmurs, sometimes called functional or physiologic murmurs, are the most common type found in children. They occur when blood flows through a normal heart at a normal rate, creating turbulence that can be heard. These murmurs are typically soft, short, and vary with breathing or body position. They are more likely to be heard in children with thinner chest walls or during times of rapid growth, fever, or anemia.

According to Hopkins Medicine, innocent heart murmurs are harmless and do not affect a child's health or activity level. They often disappear on their own as the child grows. A pediatrician can usually distinguish an innocent murmur from a pathologic one during a routine exam by listening to its characteristics and checking for associated symptoms.

Why Innocent Murmurs Usually Mean a Healthy Heart

A heart murmur is essentially an extra sound that happens as blood flows through the heart. Instead of the usual "lub-dub," a murmur adds a whooshing or swishing noise. Most murmurs, especially in children, are perfectly harmless. They are often caused by normal blood flow and are known as innocent murmurs. In fact, conditions like innocent heart murmurs are common and typically don't signal any underlying health problem.

However, some murmurs can indicate a structural issue in the heart. These are called pathological murmurs and may require closer attention. Understanding the difference between these two types is important for knowing when to seek care. For a deeper look at what these sounds mean and how they are classified, you can read more in our guide on understanding pediatric heart murmurs.

Innocent vs. Pathological Murmurs

The distinction between innocent and pathological murmurs largely comes down to the cause. An innocent murmur occurs when blood flows normally through a healthy heart. These sounds are typically soft, brief, and tend to disappear on their own as a child grows. According to Hopkins Medicine, innocent murmurs are the most common type, and they usually don't require any treatment.

Pathological murmurs, on the other hand, are caused by an underlying heart condition, such as a structural defect or a valve issue. These are often louder, may be accompanied by other symptoms like shortness of breath or fatigue, and require evaluation by a specialist. The American Academy of Family Physicians notes that while most murmurs in children are innocent, a careful exam is necessary to rule out more serious causes.

When Do Murmurs Disappear?

Innocent murmurs often come and go, and they may disappear on their own over time. This is particularly common during periods of growth, when the heart's anatomy changes. A study in the Journal of Pediatrics points out that many innocent murmurs resolve by adolescence. The key is that these murmurs are not associated with any disease and don't cause any symptoms.

If a murmur is accompanied by concerning signs like cyanosis, poor feeding, or fainting, it's important to seek a pediatric cardiology evaluation. But for most children with an innocent murmur, no treatment is needed, and they can live perfectly healthy lives. Federal Way Pediatrics offers comprehensive evaluations to help you understand your child's heart health and give you peace of mind.

Fevers and Sickness: Why Murmurs Get Louder

A heart murmur is an extra whooshing or swishing sound heard between the normal lub-dub heartbeat sounds. In children, most murmurs are "innocent" or "functional," meaning they arise from normal blood flow and are not a sign of heart disease. The American Academy of Family Physicians notes that innocent murmurs can become louder when a child has a fever, because the increased metabolic rate during illness speeds blood flow. This is why a murmur that was barely audible at a well visit may suddenly sound more pronounced when your child has a cold or flu.

Fever and Sickness: Why Murmurs Get Louder

When your child is sick, especially with a fever, the body works harder to fight off infection. The heart beats faster and with more force, which increases the turbulence of blood flow and makes a pre-existing murmur easier to hear. This phenomenon is well described in Heart Murmurs in Children: Evaluation and Management. It's also important to remember that while fever can make a murmur louder, the underlying cause of the murmur hasn't changed; it's simply more audible. This is a reassuring point for parents who might worry that a suddenly loud murmur signals a new problem.

In fact, the relationship between fever and heart murmur loudness is so common that it's addressed in many pediatric cardiology resources. If your child develops a fever and a murmur is detected, the care team will usually treat the underlying illness first, then reassess the murmur once the fever resolves. This is a standard approach that helps distinguish innocent murmurs from those that need further evaluation by a specialist like the team at Federal Way Pediatrics.

The Most Common Murmur in Childhood

Heart murmurs come in a few different types, and knowing the difference helps parents understand what their child's pediatrician is hearing during an exam. The two most common categories are innocent (functional) murmurs and pathological (structural) murmurs. Innocent murmurs, including the very common Still's murmur, are typically harmless and often resolve on their own, while pathological murmurs require closer evaluation by a specialist. For a deeper baseline, the American Academy of Family Physicians has published detailed guidance on evaluating and managing heart murmurs in children.

An innocent murmur usually sounds soft, short, and happens in the front part of the chest. It often changes with breathing or body position and may become more noticeable when a child has a fever or is exercising. Because these sounds are made by normal blood flow, they do not indicate any problem with the heart's structure. Most children with an innocent murmur need no treatment and can live completely normal, active lives—no restrictions on play or sports.

How Doctors Diagnose and Treat Childhood Murmurs

A heart murmur is an extra whooshing or swishing sound that occurs between the normal "lub-dub" of a heartbeat. It happens when blood flows with turbulence through the heart's chambers, valves, or nearby large blood vessels. For most children, these sounds are harmless and often described as "innocent" or "functional" murmurs by pediatricians.

According to experts at Johns Hopkins Medicine, innocent murmurs are common throughout childhood and generally do not signal any underlying heart problem. They may come and go, often becoming more noticeable during times of fever, exercise, or rapid growth. In contrast, a smaller number of children have a murmur that stems from a structural heart issue, which requires careful evaluation.

Why Do These Sounds Occur?

The sound itself is simply the vibration caused by blood flowing through a normal or slightly narrow opening. A child's heart is small, and many normal variations can produce a murmur without any compromise to heart function. The American Academy of Family Physicians notes that the vast majority of murmurs found during routine checkups are benign, but distinguishing an innocent from a pathological murmur requires a careful history and physical examination.

For parents, the most reassuring step is knowing that a murmur is not a disease but rather a symptom that prompts further investigation. When a pediatrician detects a murmur, they will look for signs like cyanosis, poor feeding, rapid breathing, or fatigue, which may point to a more significant condition. These red flags are covered in detail in our guide on when to seek a heart specialist.

A Gentle Reminder for Parents

Pediatric heart murmurs fall into two broad categories, and the distinction matters for how they are managed. An innocent, or functional, murmur is caused by normal blood flow through a structurally normal heart. These are common, often come and go, and typically cause no symptoms. A pathological murmur, by contrast, stems from an underlying structural problem, such as a valve defect or a hole between heart chambers, and requires closer evaluation. The medical literature groups these clearly: an innocent murmur is harmless, while a pathological murmur signals an actual heart condition that may need treatment.

Most murmurs in children are innocent. Research published in American Family Physician notes that innocent heart murmurs are the most common cause of murmurs in children, and they rarely interfere with daily life. They often appear during periods of rapid growth and can disappear on their own. The sound comes from blood flowing faster or more turbulently through a normal heart, a phenomenon likened to water rushing through a garden hose. For parents, the key is recognizing that an innocent murmur does not limit activity and needs no restriction on sports or play.

Pathological murmurs, while less common, carry more weight. They occur when blood flows through an abnormal heart structure, such as a narrowed valve or a hole in the heart. Conditions behind these murmurs include ventricular septal defects, atrial septal defects, or valve abnormalities like pulmonary stenosis. A child with a pathological murmur may show symptoms such as poor feeding, rapid breathing, or failure to thrive, though some structural problems produce no symptoms until later. The American Academy of Family Physicians emphasizes that a thorough evaluation is essential to distinguish pathological from innocent causes and to guide treatment. For a closer look at symptoms and red flags, the guide on Heart Murmurs in Children from UVA Health is a reliable starting point.

How Doctors Tell the Two Apart

The distinction begins with a careful history and physical exam. A doctor listening to the murmur notes its timing, location, and intensity, and how it changes with the child's position or breathing. Innocent murmurs often soften when the child sits up or stands, while pathological murmurs remain constant or even intensify. The examination also checks for other signs, such as cyanosis, a bluish tint to the lips, or an abnormally rapid heart rate, which hint at an underlying issue. According to experts at Johns Hopkins Medicine, most innocent murmurs are found during a routine checkup and require no further testing once the doctor is confident they are benign.