Stridor
A harsh, high-pitched sound from a narrowed upper airway
Quick Facts
- Type: Breathing (airway) symptom
- Common causes: Croup, foreign body, swelling, laryngitis
- Sound location: Larynx, windpipe, upper airway
- Seek urgent care: Severe breathing trouble, blue lips, drooling
Overview
Stridor is an abnormal, high-pitched breathing sound caused by turbulent airflow through a narrowed or partially blocked upper airway. Unlike wheezing, which usually comes from the smaller airways deep in the lungs, stridor arises from the larynx (voice box), the windpipe (trachea), or the throat above them. It can be heard without a stethoscope and often sounds harsh, musical, or crowing.
The timing of the sound gives clues to where the narrowing is. Stridor heard mainly when breathing in (inspiratory) usually points to a problem at or above the voice box, while stridor on breathing out (expiratory) suggests narrowing lower in the trachea. Stridor is always a signal that the airway is at least partly obstructed, so it should be taken seriously, especially in children, whose airways are smaller and narrow more easily.
Common Causes
Stridor results from anything that narrows the upper airway. Causes differ between children and adults.
- Croup: A common viral infection in young children that swells the airway below the voice box and produces a barking cough with stridor.
- Inhaled foreign object: A swallowed or inhaled toy, food, or small object lodged in the airway, often with sudden onset.
- Epiglottitis: Severe, rapidly progressing swelling of the epiglottis, a medical emergency.
- Allergic reaction: Swelling of the throat and voice box from a severe allergy (anaphylaxis).
- Laryngitis and vocal cord problems: Inflammation or spasm of the voice box.
- Structural causes: Tumors, vocal cord paralysis, scarring of the windpipe, or, in infants, soft airway tissue (laryngomalacia).
Associated Symptoms
Stridor rarely occurs alone. The symptoms accompanying it help reveal the cause and how urgent the situation is.
- Barking or harsh cough (typical of croup)
- Hoarse voice or loss of voice
- Difficulty breathing, fast breathing, or visible effort with each breath
- Drooling or trouble swallowing (a worrying sign of severe throat swelling)
- Fever, sore throat, or runny nose with infections
- Bluish lips or skin, restlessness, or drowsiness, which indicate not enough oxygen
Pulling in of the skin around the ribs and neck with each breath (retractions) signals that the body is working hard to move air past the obstruction.
Diagnosis & Evaluation
Because stridor can signal a threatened airway, evaluation focuses first on how well a person is breathing. A clinician will listen to the breathing, watch the chest and neck for signs of effort, and check oxygen levels.
- History and examination: Sudden onset suggests a foreign body or allergy; gradual onset with fever points to infection.
- Oxygen monitoring: A pulse oximeter measures blood oxygen.
- Imaging: Neck or chest X-rays may show swelling, a foreign object, or narrowing.
- Laryngoscopy: A small camera to view the voice box and upper airway directly, done carefully so as not to worsen swelling.
In a child who is drooling and struggling to breathe, doctors avoid examining the throat in a way that could trigger complete obstruction, and instead prepare to secure the airway in a controlled setting.
Treatment & Management
Treatment depends entirely on the underlying cause and the severity of the airway narrowing.
- Croup: Mild cases improve with calm, humidified air; moderate to severe cases are treated with steroids and sometimes nebulized epinephrine.
- Foreign object: A lodged object must be removed, sometimes with back blows or abdominal thrusts in an emergency, or by a specialist procedure.
- Allergic swelling: Anaphylaxis is treated immediately with injected epinephrine and emergency care.
- Epiglottitis: Requires hospital care, antibiotics, and airway protection.
- Structural problems: Vocal cord paralysis, scarring, or tumors are managed by an ear, nose, and throat specialist, sometimes with surgery.
Oxygen and, in serious cases, a breathing tube may be needed to keep the airway open while the cause is treated.
When to See a Doctor
Stridor should always be evaluated, and some situations are emergencies. Call emergency services right away if a child or adult with stridor has:
- Severe difficulty breathing, gasping, or unable to speak in full sentences
- Bluish lips, face, or fingertips
- Drooling, unable to swallow, or sitting forward to breathe
- Sudden stridor after a choking episode or insect sting
- Drowsiness, confusion, or unresponsiveness
For milder, gradually worsening noisy breathing without these danger signs, contact a doctor promptly for assessment, especially in young children or if it keeps returning.
Frequently Asked Questions
What is the difference between stridor and wheezing?
Stridor is a harsh, high-pitched sound usually from the upper airway, such as the voice box or windpipe, and is often heard while breathing in. Wheezing is a whistling sound from the smaller airways in the lungs, usually heard while breathing out. The location and timing help doctors tell them apart.
Is stridor in a child always an emergency?
Not always, but it should always be taken seriously. Mild stridor from croup may settle with calm and humidified air, but stridor with severe breathing trouble, drooling, blue lips, or drowsiness is an emergency. Call emergency services if these danger signs appear.
Can stridor happen in adults?
Yes. In adults, stridor can come from allergic swelling, vocal cord problems, scarring or tumors of the windpipe, or an inhaled object. Adult stridor should be evaluated promptly because it signals a narrowed airway.
What should I do if stridor starts suddenly after eating?
Sudden stridor or noisy breathing after eating or while playing with a small object may mean something is stuck in the airway. If the person can still cough or speak, encourage coughing and seek urgent help. If they cannot breathe, speak, or turn blue, call emergency services and begin choking first aid.
Does stridor mean a serious infection?
Stridor can come from infections like croup or epiglottitis, but it can also be caused by allergies, foreign objects, or structural airway problems. Because the cause ranges from mild to life-threatening, any new stridor deserves medical assessment.
References
- Mayo Clinic. Croup — Symptoms and causes.
- National Institute of Allergy and Infectious Diseases (NIAID). Anaphylaxis.
- MedlinePlus, U.S. National Library of Medicine. Breathing sounds.
- American Academy of Pediatrics. Stridor and noisy breathing in children.