What Is Stridor?

Stridor is a high-pitched sound you make when you breathe through a narrow or partly blocked airway. Air can’t flow through your lungs smoothly, so it’s harder to breathe. Stridor is usually loudest when you breathe in.

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

Types of Stridor

The type depends on the cause and where it is in your body. They include:

  • Inspiratory stridor. 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. The sound happens when you exhale, or breathe out. The cause could be a problem farther down your airway.
  • Biphasic stridor. This is sound when you inhale and exhale. There may be a problem with the spongy tissue called cartilage just below your vocal cords.
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Lung Sounds
Rhonchi, Rales, and Stridor: What Different Lung Problems Sound LikeCompare the sound of healthy lungs to noises that indicate a bigger health issue like pneumonia, rales, and other conditions.69UpToDate: "Assessment of stridor in children."<br> Medscape: "Breath Sound Assessment."<br> Medline Plus: "Breath sounds."<br> MedEdu, LLC.<br> Pond5.<br> AudioJungle./delivery/aws/7d/aa/7daac60e-a648-3a5e-8f01-3370f457f3e6/body-sounds-lungs_,4500k,2500k,1000k,750k,400k,.mp409/20/2019 11:52:0018001200Photo of lungs 3d/webmd/consumer_assets/site_images/article_thumbnails/video/body-sounds-lungs.jpg091e9c5e81d4d5bb

Stridor Causes

Causes of 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. 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:

  • Gasps for air
  • Flares their nostrils when they breathe
  • Pulls in their neck and chest with each breath
  • Turns blue
  • Has pauses in their breathing
  • Starts to act differently
  • Passes out

Other rare genetic causes of stridor include:

Vocal cord paralysis. This is also called vocal fold paralysis. It means 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. With this condition, the airway narrows when cartilage in the windpipe doesn’t form the way it should. 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, they might need surgery. But they usually outgrow the problem without treatment.

Causes of stridor in toddlers and children

When it’s not caused by a condition that they were born with, stridor in toddlers and infants is typically because of an infection like croup, papillomatosis, or epiglottitis. An injury, inhaling food, or inhaling an object can also lead to stridor.

Causes of 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
  • Surgery to your thyroid, chest, or esophagus
  • A breathing tube (intubation)
  • Subglottic or tracheal stenosis
  • Epiglottitis
  • Tests like bronchoscopy or laryngoscopy
  • Airway injury
  • Laryngitis
  • Tonsillitis
  • Smoke inhalation

Stridor Risk Factors

Stridor is more likely to happen in children because their airways are narrower than those of adults, so they can get blocked more easily.

Stridor Diagnosis

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 lighted camera on the end of a flexible tube.
  • Bronchoscopy. Your doctor uses a long, thin tube called a bronchoscope to look into your lungs.
  • Imaging tests. You might get an X-ray, a CT scan, fluoroscopy, an MRI or other scans. 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.
  • Spirometry. This test measures how much air you can breathe in and out.
  • Spit test. This is when you cough up what you can from your lungs so the doctor can see if there’s an infection.
  • Electromyography (EMG). Your doctor puts a tiny needle into a muscle in your throat and measures the electrical current going through your nerves and muscles.

Stridor Complications

Without treatment, a blocked airway can be dangerous or deadly.

Stridor Treatment

Treatment depends on how severe the blockage is and what’s causing your stridor. Your doctor might take a “wait and see” approach. Or they might treat the cause with 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 July 02, 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."

Mount Sinai: “Stridor.”

Stanford Children’s Health: “Stridor in Children.”

Nationwide Children’s: “Subglottic Stenosis.”

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