Stridor

What is stridor?

Stridor is a noise that is caused by turbulent breathing, or disruptive breathing. It means air is not flowing from the nose or the mouth into the lungs in the typical fashion. In other words, when air flows in and out of your child’s body, it hits little speedbumps—blockages or narrowing—along the way and makes a specific sound. That sound is stridor. Stridor often originates from a blockage in the voice box, windpipe, or lungs.

What are the symptoms of stridor?

Stridor is not a diagnosis; it is a symptom, like runny nose. It is noisy breathing that is usually high-pitched. If your child looks sick or is struggling to breathe, see your doctor or seek emergency help.

What causes chronic stridor?

It’s important to figure out what is causing your child’s stridor. Your doctor will ask investigative questions, such as: How long has it been happening? Is it getting better or worse? Does it come and go? What are its characteristics? Loud or soft, rattly or squeaky? Your pediatrician, your family doctor, or a pediatric otolaryngologist (ear, nose, and throat [ENT] specialist) will then try to figure out the cause of stridor from these clues. There can be very common causes that are not serious, or there can be more severe causes of stridor.

Should I see my doctor if I suspect stridor?

Yes. It should always be investigated. It might be due to a benign (not harmful) reason, such as croup (a childhood infection) or a floppy voice box (when a baby’s voice box is soft and floppy and temporarily blocks the airway, also called laryngomalacia). Or it might be more severe, such as vocal cords that are not moving, a lodged foreign object, or tumors in the voice box. If stridor has been occurring for a while, start with your pediatrician. If stridor starts suddenly and you are worried that your child cannot breathe, call 911 or go to the emergency room.  

What type of specialist treats stridor?

If you suspect stridor, your child’s pediatrician might refer you to a pediatric otolaryngologist (ear, nose, and throat [ENT] specialist) like our specialized team here at Stanford Medicine Children’s Health. The pediatric otolaryngologist will evaluate your child’s voice box, windpipe, and lungs to find the source of the stridor.  

How do you diagnose stridor?

Our care team within Pediatric Otolaryngology (ear, nose, and throat) starts by asking a lot of questions about your child’s stridor. Next, we perform a physical exam and take a health history to rule out obvious causes, such as an upper respiratory infection or reflux. If we need more information, we will perform one or more of the following tests:

• Flexible laryngoscopy. A thin, flexible tube with a camera is used like a drone to see deep into your child’s throat and look at the voice box (larynx). We check to see if there are any tissues that are swollen, look for a narrowing of the throat, and watch for foreign objects that might have become lodged in the throat or voice box. It takes just a few minutes, usually without the need of medication, and we can perform it on children as young as 1 day old in the office. We can often find the cause of stridor with this simple test.
• Microlaryngoscopy. On the occasion that we cannot identify the cause of stridor with a laryngoscopy, we may perform this test, which lets us see the vocal cords in great detail via a microscope. The procedure is performed through the nose or mouth in the operating room under sedation.
• Bronchoscopy. In this advanced test, we use a scope—a thin tube with a camera—that lets us see down your child’s entire airway and into the lungs. The procedure is performed through the nose or mouth in the operating room under sedation.

Does stridor always mean there is a problem?

No. Sometimes, babies are simply noisy breathers. They are gaining weight and growing well, and we think of them as pleasant squeakers—something that is not worrisome. But when stridor comes on suddenly, it must be evaluated by a doctor.

What is the difference between stridor and wheezing?

Stridor is often loudest when breathing in, but it can happen when breathing out. We think of wheezing as occurring when we breathe out, when we push air out of our lungs. Similarly, stridor can be confused with snoring or stertor (a low-pitched noise that comes from the nose, tongue, or back of throat), which are caused by an obstruction high up in the airway.   

Can stridor go away on its own?

Sometimes. The most common cause of stridor in babies is floppy voice box, or laryngomalacia. In some infants, the cartilage in the voice box hasn’t fully developed, or the voice box muscles are not yet strong enough. This causes stridor. It is usually not a concern, and it often resolves on its own around 1 year of age. It’s always important to get an accurate diagnosis to learn the true cause of stridor.

To learn more about stridor in children, go to the health topic page >