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Health condition · Clinically reviewed

Childhood croup and stridor, from a barking cough at midnight to a plan by morning.

Most croup is viral, self-limiting and beautifully steroid-responsive. A small number of children are hiding something more serious. This guide helps you tell the difference.

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Why trust this guide

  • 01

    Clinically reviewed

    Written by our editorial team and reviewed by a UK-registered clinician before publication.

  • 02

    Sourced from guidance

    Checked against NICE CKS, BTS and RCPCH standards you can see at the end.

  • 03

    Current for 2026

    Reflects modern UK practice on oral dexamethasone, nebulised adrenaline and specialist paediatric airway pathways.

Key facts

Noisy breathing at a glance.

The essentials, in plain English - the common causes, the frightening ones, and how UK teams treat them today.

  • What it is

    Noisy breathing in a child caused by narrowing somewhere in the upper airway. Croup is by far the most common cause.

  • Croup

    Viral laryngotracheobronchitis, usually parainfluenza type 1. Peak age 1 to 2 years, range 6 months to 6 years.

  • Classic sound

    A barking, seal-like cough with inspiratory stridor and a hoarse voice, worse at night after a coryzal prodrome.

  • First-line treatment

    A single oral dose of dexamethasone 0.15 mg/kg (up to 12 mg) for mild-to-moderate croup, given in one visit.

  • Emergency picture

    High fever, drooling, tripod posture and a toxic, quiet child suggests epiglottitis or bacterial tracheitis. Do not distress the child.

  • Structural causes

    Laryngomalacia is the commonest congenital cause of stridor in infants and usually settles by 12 to 24 months.

Why this guide matters

A short list of causes, a clear list of red flags.

Most noisy breathing in children is croup. A handful of causes are dangerous. This page separates the two so parents can act with confidence.

  • Croup is common and treatable

    Viral laryngotracheobronchitis - parainfluenza most often - and a single oral steroid dose is the mainstay of care.

  • Some causes are emergencies

    Epiglottitis, bacterial tracheitis, inhaled foreign body and anaphylaxis are rare but life-threatening. Recognise them early.

  • Structural causes exist too

    Persistent or recurrent stridor deserves a paediatric ENT opinion - laryngomalacia, vascular rings and subglottic pathology can hide in plain sight.

Causes

What can narrow a child’s airway.

The location of the narrowing usually determines the sound. Supraglottic and glottic causes give inspiratory stridor; subglottic and tracheal causes give biphasic stridor; lower airway causes give expiratory wheeze.

  • Viral croup

    Laryngotracheobronchitis, usually parainfluenza type 1, also RSV, adenovirus, influenza and COVID. Subglottic oedema in children aged 6 months to 6 years.

  • Spasmodic croup

    Recurrent sudden nocturnal episodes without fever. An allergic and reactive picture that responds to steroids in the same way.

  • Epiglottitis

    Historically Haemophilus influenzae type b - now rare with vaccination but still occurs. Rapid, toxic, drooling, tripod. A medical emergency.

  • Bacterial tracheitis

    Staphylococcus aureus or Streptococcus. Severely unwell with purulent membranes in the trachea and a poor response to adrenaline alone.

  • Inhaled foreign body

    Sudden choking history, often in a toddler, with wheeze and unilateral reduced air entry. Needs urgent rigid bronchoscopy.

  • Laryngomalacia

    Commonest congenital cause of stridor. Inspiratory noise, worse supine and with feeding, in a well infant. Usually resolves by 1 to 2 years.

  • Tracheomalacia

    Floppy trachea giving expiratory noise, often worse with crying or upper respiratory infection.

  • Vocal cord paralysis

    Unilateral or bilateral. Weak or absent cry, feeding difficulty and a persistent noise. Needs paediatric ENT and laryngoscopy.

  • Subglottic stenosis

    Congenital or acquired - often after prolonged neonatal intubation. Recurrent croup-like episodes are a classic clue.

  • Laryngeal cleft, vascular ring

    Rare structural causes. Recurrent chest infections, feeding difficulty and stridor that never really settles.

  • Angioedema and anaphylaxis

    Sudden lip and tongue swelling, urticaria and stridor after a trigger. Needs intramuscular adrenaline - see our anaphylaxis guide.

  • Inhalation injury

    Smoke, steam or toxic exposure. Assume airway involvement even before visible swelling if the mechanism fits.

  • Airway tumours

    Subglottic haemangioma, lymphatic malformation and laryngeal papillomatosis (recurrent respiratory papillomatosis, HPV-related). Persistent, unusual stridor.

  • Vocal cord dysfunction

    Older children and adolescents. Paradoxical vocal cord movement that mimics asthma or croup but does not respond to bronchodilators.

How the diagnosis is made

From first noisy breath to a safe plan.

Assessment is deliberately gentle. Distressing an obstructed child can turn a manageable problem into a critical one.

  1. 01

    Assessing

    Do not distress the child

    Keep the child on a parent’s lap, calm and undisturbed. Agitation can precipitate complete airway obstruction if epiglottitis or severe croup.

  2. 02

    Assessing

    Clinical assessment

    Type of stridor (inspiratory, biphasic, expiratory), voice, cough, drooling, work of breathing, colour and consciousness.

  3. 03

    Assessing

    Score the severity

    The Westley croup score grades mild, moderate, severe and impending respiratory failure. This drives treatment.

  4. 04

    Confirming

    Imaging is not routine

    Croup is a clinical diagnosis. Lateral neck films are rarely needed. CXR only if foreign body, pneumonia or tracheal deviation is suspected.

  5. 05

    Confirming

    Bronchoscopy for red flags

    Rigid bronchoscopy under paediatric ENT for suspected inhaled foreign body, persistent stridor or structural airway concern.

  6. 06

    Specialist

    Laryngoscopy for structural cases

    Flexible laryngoscopy grades laryngomalacia, tracheomalacia, vocal cord paralysis and subglottic pathology.

  7. 07

    Specialist

    Selective MRI and bloods

    MRI for suspected vascular ring or mediastinal cause. Bloods reserved for suspected bacterial infection or systemic illness.

Typical timeline: most children improve within hours of steroid, and are back to themselves within days.

Symptoms

What noisy breathing actually looks and sounds like.

The type of noise, the child’s posture and the presence or absence of fever all point to the underlying cause.

  • Barking, seal-like cough

    The signature sound of croup, often starting suddenly at night after a coryzal prodrome.

  • Inspiratory stridor

    A harsh noise on breathing in, generated by narrowing at the larynx or upper trachea.

  • Biphasic stridor

    Noise on both in and out, suggesting narrowing at the subglottis or upper trachea, and a warning sign.

  • Expiratory wheeze

    A whistle on breathing out, from the lower trachea or bronchi. Consider foreign body or asthma.

  • Hoarse voice or cry

    Suggests involvement of the vocal cords, common in croup and vocal cord disorders.

  • Drooling and tripod posture

    A child leaning forward, drooling and refusing to swallow is a red flag for epiglottitis or bacterial tracheitis.

  • Recession and nasal flaring

    Sucking in at the neck, ribs or sternum reflects increased work of breathing.

  • Red flag - cyanosis or drowsiness

    Blue lips, agonal breathing, exhaustion or reduced consciousness need a 999 response.

Treatment

How UK teams treat croup and stridor.

Oral dexamethasone for almost everyone with croup, nebulised adrenaline for the sickest, and controlled airway management for suspected bacterial airway infection.

  • Oral dexamethasone

    Single dose 0.15 mg/kg (max 12 mg) for mild-to-moderate croup. Reduces symptoms, admission and reattendance. First-line and evidence-based.

  • Nebulised budesonide

    An alternative steroid route if the child cannot tolerate oral. Given as 2 mg via nebuliser.

  • Nebulised adrenaline

    5 mL of 1:1000 adrenaline for moderate-to-severe croup. Rapid but transient relief for around 30 minutes. Observe for rebound afterwards.

  • Oxygen

    Given by whichever route is best tolerated if the child is hypoxic. Do not force a mask on a distressed child.

  • Antibiotics

    Not indicated for viral croup. Reserved for bacterial tracheitis or epiglottitis, typically with IV ceftriaxone.

  • Emergency airway management

    Suspected epiglottitis needs urgent paediatric anaesthetics and ENT in theatre for gaseous induction and controlled intubation.

  • Rigid bronchoscopy

    Removes an inhaled foreign body and inspects the airway. Performed by paediatric ENT under general anaesthesia.

  • Supraglottoplasty

    Surgical option for severe laryngomalacia causing feeding problems, failure to thrive or significant obstruction.

Where specialist paediatric airway care happens

Complex or recurrent airway cases are managed at UK specialist paediatric airway centres including Great Ormond Street Hospital, Alder Hey, Birmingham Children’s Hospital, Sheffield Children’s and Bristol Royal Hospital for Children. Prevention rests on Hib, influenza, COVID and RSV protection (maternal vaccination and infant nirsevimab). See our bronchiolitis guide for more on RSV.

What this guide is based on

The sources behind every claim on this page.

UK national guidance and paediatric specialist standards, current at the time of last review.

Key references

Guidelines and standards we relied on.

A quiet reminder

This guide is for information, not medical advice.

Your GP, out-of-hours service or A&E team knows your child and can tell you which parts apply. If you are worried, seek help.

  • NICE CKS. Croup - management in children.

  • British Thoracic Society (BTS). Paediatric respiratory care standards.

  • Royal College of Paediatrics and Child Health (RCPCH). Acutely unwell child guidance.

  • UK Health Security Agency. Green Book - Hib, influenza, COVID and RSV immunisation.

Red flags

When noisy breathing needs urgent action.

Most croup can be safely managed at home. These are the features that change that - either into an urgent GP review, or a 999 call.

  • Cyanosis or agonal breathing

    Blue lips, gasping or exhaustion is a life-threatening picture. Call 999 and prepare for airway support.

  • Drooling and tripod posture

    Refusing to swallow, drooling and leaning forward suggests epiglottitis or bacterial tracheitis. Do not examine the throat.

  • Biphasic stridor at rest

    Noise on both in and out while the child is quiet suggests significant subglottic or tracheal narrowing.

  • Sudden choking history

    A well child who suddenly coughs, chokes or develops stridor may have inhaled a foreign body. Needs urgent bronchoscopy.

  • Toxic, quiet or drowsy child

    A child who has gone from noisy to quiet may be tiring and heading towards respiratory failure.

  • Under six months with stridor

    Young infants have less airway reserve. Have a low threshold for admission and specialist review.

  • Immunocompromise

    Chemotherapy, immunodeficiency or long-term steroids raise the risk of bacterial and unusual pathogens.

  • Recurrent or persistent stridor

    More than a few croup-like episodes, or noise that never fully settles, warrants paediatric ENT assessment for a structural cause.

  • Anaphylaxis features

    Sudden stridor with lip or tongue swelling, urticaria or wheeze needs intramuscular adrenaline. See our anaphylaxis guide.

Living with it

Getting through the barky nights, safely.

Four practical points that help most families ride out a croup episode - and know when to stop riding it out and get help.

A quiet reminder

A calm child is a wider airway.

Everything you can do to keep your child settled - lap cuddles, soft voices, familiar toys - genuinely helps their breathing.

  1. 01 Calm

    Keep the child calm

    Sit them upright on a parent’s lap. Distress narrows the airway further. Familiar toys and quiet voices help.

  2. 02 At night

    Cool night air can help

    Many croup episodes ease at an open window or in the car on the way to hospital. Steam is no longer recommended and can scald.

  3. 03 Fluids

    Fluids and fever control

    Small sips often, and paracetamol or ibuprofen for fever and discomfort if age-appropriate.

  4. 04 Safety net

    Know when to get help

    Any stridor at rest, colour change, drooling or a tiring child needs urgent review by 111, out-of-hours or 999.

Frequently asked

Everything parents ask us about croup.

Quick answers on treatment, red flags, epiglottitis, laryngomalacia and prevention.

  • What is croup?

    Croup is a viral inflammation of the larynx and trachea, most often caused by parainfluenza type 1. It produces a barking cough, inspiratory stridor and a hoarse voice, usually in children aged 6 months to 6 years, and is worse at night.

  • How is croup treated?

    The mainstay for mild-to-moderate croup is a single oral dose of dexamethasone 0.15 mg/kg (up to 12 mg). Nebulised budesonide is an alternative if oral is not tolerated, and nebulised adrenaline is added for moderate-to-severe cases. Most children are back to their usual selves within a couple of days.

  • When should I take my child to hospital?

    Take your child to A&E, or call 999, if they have stridor at rest, blue lips, severe chest recession, drooling with a fever, are drowsy or floppy, or if you are simply worried they are getting worse. Trust your instincts.

  • Is epiglottitis still a thing?

    Epiglottitis is now rare in the UK because of Hib vaccination, but it still occurs. A high fever, toxic-looking child who is drooling and sitting forward should be handled very carefully. Do not distress them, do not examine the throat and get urgent paediatric anaesthetic and ENT help.

  • My baby has always been a noisy breather. Is that croup?

    Long-standing inspiratory noise, worse when lying flat or feeding, in a well infant is more likely laryngomalacia - the commonest congenital cause of stridor. It usually settles by 12 to 24 months, but persistent or severe symptoms deserve a paediatric ENT opinion.

  • Can I prevent croup?

    You cannot prevent every viral illness, but keeping routine childhood vaccinations up to date - especially Hib, influenza, COVID and, where offered, RSV protection - reduces the burden of the most serious airway infections.

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