Approach to stridor

Approach to a complaint

Stridor is a high-pitched breathing noise caused by a narrowed upper airway; it can be an emergency, above all in children.

Updated Nov 5, 2026

See it in 3D: Epiglottis · Vocal folds · Cricoid cartilage · Trachea

What it is

Stridor is a harsh, high-pitched breathing sound made by turbulent airflow through a narrowed upper airway: larynx, subglottis or trachea. It is not a diagnosis but a sign of obstruction, and it can be life-threatening. Young children are at higher risk because their airways are narrower. The first aim is to recognise severity and protect the airway; then the cause is sought from age, speed of onset, fever and associated symptoms. Stridor in infants (laryngomalacia and other congenital causes) is covered on the page on stridor in children.

Key questions in the history

Sudden onset (foreign body, anaphylaxis) or gradual (croup, tumour)?
Fever and a toxic look? Drooling or trouble swallowing?
Any choking while eating or playing with small objects?
Exposure to allergens, stings or drugs; swelling of the face, lips or tongue?
Previous intubation, neck surgery or tracheostomy?
Vaccines up to date, especially Haemophilus influenzae type b and diphtheria?
In adults: progressive hoarseness, smoking or weight loss?

Causes and classification

Infectious: croup (laryngotracheobronchitis), epiglottitis, bacterial tracheitis, diphtheria and pharyngeal abscesses.
Foreign body in the larynx or trachea.
Allergic: anaphylaxis and angioedema.
Traumatic and iatrogenic: inhalation injury, prolonged intubation, neck surgery.
Tumours: laryngeal cancer and recurrent respiratory papillomatosis.
Neurological: bilateral vocal fold paralysis.
Congenital in infants, such as laryngomalacia: see the page on stridor in children.

Step-by-step approach

Assess severity without upsetting the patient: colour, work of breathing, retractions, consciousness and oxygen saturation.
Keep the child in the carer's arms and in the position the child prefers; do not force the child to lie down.
Severe obstruction: oxygen, call the airway team and prepare for intubation or a surgical airway.
Witnessed choking with an ineffective cough: age-appropriate airway clearance manoeuvres.
High fever, drooling and a toxic look: manage as epiglottitis; secure the airway in theatre or ICU.
Barking cough with low fever after a cold: croup; grade severity (for example with the Westley score).
Urticaria, hypotension or swelling of the face or tongue: anaphylaxis; intramuscular epinephrine without delay.
Stable patient: neck and chest X-ray, pulse oximetry, laryngoscopy or bronchoscopy as suspicion dictates.
Adult with progressive stridor: laryngoscopy to rule out a tumour or vocal fold paralysis.

Causes of acute stridor

Cause	Typical age	Clues	Management
Croup	3 months to 5 years	Barking cough, hoarseness, low fever, worse at night	Corticosteroid; nebulised epinephrine if moderate or severe
Epiglottitis	Unvaccinated child or adult	High fever, drooling, dysphagia, leaning forward	Controlled airway in theatre or ICU; parenteral antibiotic
Foreign body	Infant and preschool child	Sudden choking, cough, no fever	Airway clearance; bronchoscopy
Anaphylaxis or angioedema	Any age	Urticaria, swollen lips or tongue, hypotension	Intramuscular epinephrine
Bacterial tracheitis	Child	Toxic look after croup that gets worse	Hospital, antibiotic and airway management
Papillomatosis or laryngeal tumour	Child (HPV) or adult smoker	Progressive hoarseness before the stridor	Laryngoscopy and referral to ENT

Red flags

Stridor at rest, marked retractions or cyanosis.
Drooling, inability to swallow or sitting leaning forward.
Drowsiness or agitation: hypoxia or exhaustion.
Stridor that fades while breathing effort rises: near-complete obstruction.
Sudden onset after a choking episode.
Infant under 6 months, or recurrent or persistent stridor.

Next step / Initial management

Mild croup: outpatient care with oral corticosteroid (dexamethasone) and warning signs; moderate or severe: nebulised epinephrine, oxygen and observation in the emergency department.
Epiglottitis: do not examine the pharynx or do procedures that upset the patient; parenteral antibiotic and corticosteroid once the airway is secure.
Anaphylaxis: immediate intramuscular epinephrine, oxygen and fluids.
Refer urgently, with immediate accompanied transfer, any stridor at rest, epiglottitis, suspected foreign body or anaphylaxis.
Chronic or recurrent stridor, or an adult with progressive hoarseness: priority referral to ENT for laryngoscopy.

Test yourself

Think of the answer, then tap the question to see it.

A 2-year-old has a barking cough, hoarseness and stridor that worsen at night after a cold. Diagnosis and management?

Viral croup, usually parainfluenza. Corticosteroid; if there is stridor at rest or moderate to severe distress, nebulised epinephrine and observation.

An unvaccinated child has high fever, is drooling and sits leaning forward. What must you not do?

Do not examine the throat with a tongue depressor or upset the child: it may trigger complete obstruction. Suspect epiglottitis; secure the airway in theatre or ICU.

What does stridor that fades while breathing effort rises mean?

Exhaustion and near-complete obstruction: a sign of severity, not improvement; intubation may be needed.

An 18-month-old suddenly started coughing with stridor while eating peanuts, with no fever. What is the main suspicion?

A foreign body in the airway; it needs urgent assessment and bronchoscopy.

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Connections

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Educational content; it does not replace a medical assessment and is not a clinical instruction. For a real case, follow current guidelines and specialist advice.

Sources: Stridor (MedlinePlus Medical Encyclopedia) (U.S. National Library of Medicine, NIH, 2026); Croup (MedlinePlus Medical Encyclopedia) (U.S. National Library of Medicine, NIH, 2026); Epiglottitis (MedlinePlus Medical Encyclopedia) (U.S. National Library of Medicine, NIH, 2026); Recurrent Respiratory Papillomatosis or Laryngeal Papillomatosis (National Institute on Deafness and Other Communication Disorders (NIDCD), NIH, 2017).

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