Stridor isn’t actually a cough. It’s an abnormal, high-pitched sound that happens when air forces its way through a narrowed airway. People often search for “stridor cough” because the two frequently show up together, especially in children with croup, where a harsh barking cough and a whistling breathing sound can occur at the same time. Understanding the difference matters because stridor signals a partially blocked airway, which can range from mild and manageable to a medical emergency.
What Stridor Actually Sounds Like
Stridor is a loud, musical sound with a fairly constant pitch, sometimes described as a high-pitched whistle or a squeaky, vibrating noise. It’s produced when air flows irregularly through a section of the airway that has become too narrow. Unlike a cough, which is a forceful burst of air your body uses to clear the throat or lungs, stridor is a continuous sound tied to the rhythm of breathing itself.
When stridor happens tells you something about where the blockage is. Stridor heard on breathing in (inspiratory stridor) points to a narrowing at the level of the voice box. Stridor heard on breathing out (expiratory stridor) suggests a problem lower down in the windpipe or the airways leading to the lungs. Some people have stridor in both directions, which usually means the narrowing is right at or just below the vocal cords.
Why Stridor and Croup Get Confused
Croup is the most common reason parents encounter stridor, and it’s also why “stridor cough” gets searched so often. Croup is a viral infection that swells the airway just below the vocal cords. That swelling produces two distinct sounds: a barking cough that sounds like a seal, and stridor, the high-pitched whistle when the child breathes in. The barking cough happens because air forced out through swollen vocal cords vibrates in an unusual way. The stridor happens because the narrowed airway resists the flow of air coming back in.
Both sounds can be alarming, especially at night when croup tends to flare. But they’re separate events. The cough is active and deliberate. Stridor is passive, happening simply because the child is trying to breathe through a tight space. A child can have the barking cough without stridor (mild croup) or develop stridor as the swelling worsens.
Common Causes in Children
The age of the child narrows the list of likely causes considerably. In babies under six months, the most common culprit is laryngomalacia, a condition where the soft tissue above the vocal cords is floppy and collapses inward during breathing. Laryngomalacia tends to cause stridor that gets worse during feeding or when the baby is lying on their back. Most children outgrow it as their airway tissue firms up. Other causes in this age group include vocal cord paralysis and narrowing of the airway from birth.
In children older than six months, croup dominates. It typically affects kids between six months and three years of age, peaks in the fall and early winter, and resolves within a few days. Beyond croup, other causes in this age group include a swallowed or inhaled object stuck in the airway, bacterial infections of the windpipe, and epiglottitis, a serious infection of the flap of tissue that covers the windpipe during swallowing.
Croup vs. Epiglottitis
Both croup and epiglottitis produce stridor, but they look very different in practice. Croup comes with a barking cough and no drooling. Epiglottitis comes with drooling and no coughing. In a study comparing the two, coughing predicted croup with near-perfect accuracy, while drooling predicted epiglottitis with 79% sensitivity and 94% specificity. A child with epiglottitis will also prefer to sit upright, lean forward, and refuse to swallow. Epiglottitis is rare today thanks to vaccination but remains a medical emergency when it does occur.
Causes in Adults
Stridor in adults is less common and often points to a different set of problems. The most frequent causes include tumors or growths in or near the airway, vocal cord paralysis (sometimes after surgery on the neck or chest), severe allergic reactions causing throat swelling, infections or abscesses in the throat, and narrowing of the windpipe from scar tissue. A condition called paradoxical vocal fold movement, where the vocal cords close when they should open, can also mimic stridor. It’s sometimes mistaken for asthma because it causes difficulty breathing and wheezing-like sounds, but asthma medications don’t help.
Stridor vs. Wheezing
People often confuse stridor with wheezing, but they come from different places. Wheezing originates in the smaller airways deep in the lungs and is most common in asthma or bronchitis. It’s usually heard when breathing out. Stridor comes from the large upper airway (the voice box or windpipe) and is typically loudest when breathing in. Stridor also tends to be louder and more clearly audible without a stethoscope, while wheezing is often softer and more diffuse. The distinction matters because their causes and treatments are completely different.
How Stridor Is Treated
Treatment depends entirely on the cause. For croup, which accounts for most childhood stridor, a single dose of a steroid medication is the standard approach. High-quality trial evidence shows that one dose reduces the severity of symptoms and lowers the chance of needing to return to the emergency room or be hospitalized. In moderate to severe cases where a child is struggling to breathe, doctors may also use a nebulized form of adrenaline, which rapidly shrinks the swollen tissue by constricting blood vessels in the airway lining. The effect is fast but temporary, which is why children who receive it are monitored afterward.
For stridor caused by a foreign object, removal of the object resolves the problem. For structural issues like laryngomalacia in infants, the approach is usually watchful waiting since most cases resolve on their own. Adults with stridor from tumors, scar tissue, or vocal cord problems typically need evaluation with a small camera passed through the nose to visualize the airway directly.
Signs That Stridor Is an Emergency
Mild stridor that only appears when a child is crying or agitated, and disappears at rest, is generally not dangerous. Stridor that persists at rest is more concerning because it means the airway is significantly narrowed even during calm breathing. The following signs alongside stridor indicate a serious problem that needs immediate attention:
- Retractions: visible pulling in of the skin between the ribs, above the collarbone, or at the notch of the throat with each breath, meaning the body is working hard to move air
- Color changes: bluish or grayish tint to the lips, fingernails, or skin, signaling that not enough oxygen is getting through
- Drooling with inability to swallow: suggests epiglottitis or a severe throat obstruction
- Sudden onset after eating or playing with small objects: points to a foreign body in the airway
- Rapidly worsening breathing difficulty: any stridor that gets louder and more labored over minutes rather than hours
A child who is sitting very still, leaning forward, and refusing to lie down is using body positioning to keep their airway as open as possible. This posture, combined with stridor, is a red flag. In adults, stridor that develops after an allergic reaction, particularly with facial or throat swelling, can signal anaphylaxis and requires emergency treatment immediately.