What Is Stridor?

Air can’t flow through your lungs smoothly when something partly blocks or narrows your airway. That makes it harder to breathe and leads to a high-pitched sound called stridor. It’s usually loudest when you breathe in, but you might hear it when you breathe out, too.

Stridor isn’t a condition, but a symptom of something else. It can start suddenly or happen slowly over time.


Types of Stridor

The type depends on the cause and location. They include:

Inspiratory stridor. This means the sound happens when you inhale, or breathe in. It may be because of floppy tissue around the vocal cords, especially in children.

Expiratory stridor. This means the sound happens when you exhale, or breathe out. The cause may be a problem farther down your airway.

Biphasic stridor. This is when there’s sound during both. There may be a problem with the spongy tissue called cartilage just below your vocal cords.

Stridor in Infants

Stridor in infants usually means your baby was born with a problem that causes partial blockage of their airway.

Laryngomalacia is the most common of these genetic conditions. It’s when the tissue around your vocal cords is loose and floppy. It usually isn’t serious and goes away on its own in about 18 months. Your child might need surgery, but that’s rare. Call your doctor right away if your child has these symptoms:

  • Stridor that gets worse the first 4 to 8 months
  • Feeding problems like choking or inhaling food
  • Low weight
  • Throwing up

Call 911 if your child:

  • Pulls in their neck and chest with each breath
  • Turns blue
  • Stops breathing for more than 10 seconds

Other rare genetic causes of stridor include:

Vocal cord paralysis. Your doctor might call it vocal fold paralysis. That’s when your vocal cords can’t move. Your baby might not be able to make normal sounds or breathe the right way. Besides stridor, you might notice:

  • A soft or weak cry
  • A breathy, quiet voice
  • Breathing in of liquids

Congenital subglottic stenosis. Here, the airway narrows when cartilage in the windpipe doesn’t form properly. The doctor might not notice it until a few months after birth, usually after a cold or other illness. Besides stridor and gasping for air, your baby might get airway infections known as croup. In serious cases, your baby might need surgery. But they usually outgrow the problem without treatment.


Stridor in Toddlers and Children

When a genetic condition isn’t the cause, stridor in toddlers and infants is typically due to an infection like croup, papillomatosis, or rarely, epiglottitis. An injury, inhaling food, or inhaling an object can also lead to stridor.

Stridor in Adults

In adults, reasons for stridor typically include issues with your airway, vocal cords, or voice box, such as:

  • An abscess (a fluid-filled sore)
  • Swelling
  • Vocal cord problems like an injury or paralysis
  • Allergies
  • Growths such as tumors
  • Inhaling food or an object

Diagnosing Stridor

Your doctor will ask about your medical history and symptoms, and they’ll do a physical exam. In a baby, they’ll look for signs of breathing problems like flared nostrils, color changes, and straining at the neck or chest. Tests might include:

Flexible laryngoscopy. This is when the doctor looks at your airway with a flexible, lighted camera on the end of a tube.

Images. You might get an X-ray, CT scan, fluoroscopy, MRI or other imaging. They make pictures of your airway and its tissues.

Blood oxygen test. Your doctor might call it pulse oximetry. It measures the amount of oxygen in your blood.

Spit test. This is when you cough up what you can from your lungs so the doctor can see if there’s an infection.


Treatment depends on what’s causing your stridor. Your doctor might take a “wait and see” approach. Or they might prescribe medications, like steroids. They may suggest surgery to take out a cyst or anything else blocking your airway.

WebMD Medical Reference Reviewed by Melinda Ratini, DO, MS on February 24, 2020



Children’s Hospital of Philadelphia: “Laryngomalacia,” “Vocal Cord Paralysis,” “Subglottic Stenosis,” “Stridor (Noisy Breathing).”

Children's National Hospital: “Pediatric Stridor.”

Merck Manual: “Stridor.”

NYU Langone Hospitals: “Diagnosing Stridor in Adults.”

Mayo Clinic: "Vocal Cord Paralysis."

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