Croup
Clinical Snapshot
Croup (laryngotracheobronchitis) is a common viral infection causing inflammation and edema of the subglottic larynx, trachea, and bronchi — the narrowest, non-distensible part of a young child's airway — producing the classic triad of a seal-like barking cough, hoarseness, and inspiratory stridor.[1] It occurs most often between 6 months and 3 years of age, though it can present as early as 3 months and as late as 15 years, and is caused by respiratory viruses, most commonly parainfluenza virus types 1 and 3; influenza A and B, adenovirus, respiratory syncytial virus, human metapneumovirus, coronaviruses (including COVID-19), and mycoplasma have also been implicated. Most croup is mild and self-limited, resolving within about 48 hours (occasionally up to 6 days), and the large majority of affected children are managed successfully as outpatients. A single dose of oral dexamethasone is the standard of care for essentially every child diagnosed with croup, regardless of severity — this is the single most important pharmacologic decision in croup management and should not be reserved only for moderate-to-severe presentations.[2]
Recognize the Condition
Typical presentation
Croup usually begins with 1-2 days of nonspecific upper-respiratory symptoms — rhinorrhea, mild cough, and low-grade fever — before the characteristic seal-like barking cough, hoarseness, and inspiratory stridor emerge. Fever can reach up to 40°C but is not required for the diagnosis.
Symptoms are classically worse at night, improve during the day, and are markedly aggravated by agitation and crying — a child who looks comfortable while calm in a caregiver's lap can still have significant stridor and retractions once upset, so severity assessment should account for this variability rather than relying on a single calm snapshot.
Obstructive symptoms generally resolve within 48 hours of onset; a minority of children remain symptomatic for up to 6 days.
Physical examination findings
- Stridor — typically inspiratory; biphasic or expiratory stridor suggests more severe airway narrowing.
- Chest wall retractions (suprasternal, intercostal, subcostal) and visible respiratory distress, present to varying degrees depending on severity.
- Voice/cry — hoarse, but the child can usually still cry and speak, unlike the muffled "hot potato" voice or near-inability to speak seen with epiglottitis.
- Signs of impending respiratory failure develop over several hours and include reduced respiratory effort, pallor, cyanosis, a dusky appearance, decreased breath sounds, and lethargy or a decreased level of consciousness — these are late findings that must never be missed (see Red Flags and Refer).
Risk Factors
- Age 6 months to 3 years (the period of greatest susceptibility); croup can occur as young as 3 months or as old as 15 years, and is rare beyond that.
- Male sex.
- Recent or concurrent viral upper respiratory infection — parainfluenza virus types 1 and 3 are the most common cause; influenza A/B, adenovirus, RSV, human metapneumovirus, coronaviruses (including COVID-19), and mycoplasma are also implicated.
- Fall and early-winter seasonality, reflecting the circulation pattern of parainfluenza virus.
- A personal history of prior croup episodes or an underlying airway abnormality (e.g., subglottic stenosis, laryngomalacia) increases the risk of recurrent or atypical (spasmodic) croup and should prompt evaluation.
Red Flags & Refer
Most children with croup can be safely managed with reassurance, a single dose of oral dexamethasone, and clear return precautions. Escalate immediately for any of the following:
- Signs of impending respiratory failure: reduced or exhausted respiratory effort, pallor or cyanosis, a dusky appearance, decreased breath sounds, or lethargy/decreased level of consciousness — these develop over several hours and represent a true airway emergency requiring immediate escalation, not a "wait and see" approach.
- Stridor at rest that is worsening or not improving despite appropriate treatment.
- Toxic appearance, high fever, drooling or inability to swallow secretions, an anxious child sitting forward in a "sniffing" position, absence of a barking cough, or rapidly progressive symptoms — these suggest epiglottitis or bacterial tracheitis rather than viral croup and require urgent airway-team involvement; do not attempt an oropharyngeal examination or lay the child supine if epiglottitis is suspected, since this can precipitate complete obstruction.
- Sudden onset of stridor, choking, or drooling with a possible history of an inhaled object — consider foreign body aspiration.
- Any impending-respiratory-failure feature or severe croup (Westley score ≥6) — arrange emergency transport; do not delay transfer to give oral medication first.
- Recurrent croup (3 or more episodes) or croup occurring outside the typical 6-month-to-3-year age range — refer for otolaryngology evaluation of an underlying structural airway abnormality.
- Poor or absent response to appropriate therapy (dexamethasone plus nebulized epinephrine as indicated) — reassess the diagnosis rather than repeating the same treatment.[3]
Assessment & Diagnosis
Differentiating croup from its dangerous mimics
Several conditions can present with acute stridor and must be actively distinguished from croup, since some require completely different, urgent management.[3]
| Feature | Croup | Epiglottitis | Bacterial tracheitis | Foreign body aspiration |
|---|---|---|---|---|
| Typical age | 6 months to 3 years | Any age (historically 2-6 years; the typical age has shifted since Haemophilus influenzae type b vaccination) | Any age, often school-age | Under 3 years (peak toddler) |
| Onset | Gradual over 1-2 days, following a viral prodrome | Sudden, rapidly progressive over hours | Starts as a viral-like illness, then sudden deterioration | Sudden, with a witnessed or suspected choking event |
| Cough | Seal-like barking cough, prominent | Absent or minimal | Barking cough with productive, copious secretions | Sudden coughing/gagging at onset, may then settle |
| Voice / swallowing | Hoarse but able to speak, cry, and swallow | Muffled voice, drooling, dysphagia, odynophagia | Hoarse; poor response to nebulized epinephrine | Usually normal voice unless the object lodges in the larynx |
| Fever | Absent to low-grade | High, sudden onset | High | Absent unless secondary infection develops |
| Appearance / position | Non-toxic; comfortable when calm | Toxic, anxious, sitting forward in a "sniffing" position | Toxic-appearing, rapidly deteriorating | Variable; acute distress at the choking event itself |
| Comments | The most common cause of acute stridor in children | Rare since Haemophilus influenzae type b vaccination, but remains an airway emergency and still occurs with non-vaccine strains.[4] | The most common bacterial superinfection following a viral-like illness, with sudden worsening and often poor response to nebulized epinephrine.[5] | The object typically lodges in the upper airway or esophagus; suspect this with any choking history, even if not clearly witnessed. |
Rarer causes of acute stridor include severe allergic reaction/angioedema (rapid onset, possible urticaria/hypotension, personal or family history of allergy), peritonsillar/retropharyngeal or other upper-airway abscess (drooling, neck stiffness, unilateral swelling, more gradual onset), and diphtheria (extremely rare, seen only with inadequate immunization; membranous pharyngitis is characteristic).
History
- Onset and duration of barking cough, hoarseness, and stridor; ask specifically whether stridor is present at rest or only with agitation/crying.
- Preceding upper respiratory symptoms (rhinorrhea, low fever) over the prior 1-2 days.
- Oral intake tolerance and hydration status.
- Any history of prior croup episodes, a known airway abnormality, or recent choking/foreign-body exposure.
- Immunization status (Haemophilus influenzae type b, diphtheria) — relevant to the differential diagnosis, not to croup management itself.
Physical examination
- Assess the child while calm, ideally on a caregiver's lap — unnecessary handling, throat examination, or IV attempts can provoke crying and transiently worsen airway obstruction and the apparent severity.
- Vital signs, with particular attention to respiratory rate and work of breathing.
- Presence and timing of stridor (at rest vs. only with agitation), chest wall retractions, and air entry on auscultation.
- Level of consciousness and colour — lethargy, pallor, or cyanosis indicate impending respiratory failure.
Investigations
Croup is a clinical diagnosis; no laboratory testing or imaging is routinely required.
- Lateral and anteroposterior soft-tissue neck radiographs are reserved for atypical presentations or a child not responding to treatment as expected — they are not needed to confirm a typical presentation. A classic but non-mandatory finding is subglottic narrowing on the AP view (the "steeple sign").
- Pulse oximetry is reserved for more severe croup, since marked airway obstruction can eventually cause hypoxia and hypercapnia; it is not needed for mild, typical cases.
- Routine bloodwork and viral testing are not needed to manage typical croup and do not change treatment.
Severity assessment: the Westley Croup Score
The Westley Croup Score combines 5 items — level of consciousness, cyanosis, stridor, air entry, and retractions — into a single severity score from 0 to 17.[6] Unlike a simple point-per-criterion tool, each criterion carries a different maximum weight (cyanosis at rest alone contributes 5 points, while stridor at its worst contributes only 2), so this chapter provides the full scoring table for teaching and structured severity communication rather than a live calculator — this non-uniform point weighting does not meet the simple, unambiguous point-sum bar required before an interactive scoring tool is safe to offer.[3]
| Criterion | Points |
|---|---|
| Level of consciousness: normal (including asleep) | 0 |
| Level of consciousness: disoriented | 5 |
| Cyanosis: none | 0 |
| Cyanosis: with agitation | 4 |
| Cyanosis: at rest | 5 |
| Stridor: none | 0 |
| Stridor: with agitation | 1 |
| Stridor: at rest | 2 |
| Air entry: normal | 0 |
| Air entry: decreased | 1 |
| Air entry: markedly decreased | 2 |
| Retractions: none | 0 |
| Retractions: mild | 1 |
| Retractions: moderate | 2 |
| Retractions: severe | 3 |
Total score interpretation: 0-2 mild, 3-5 moderate, 6-11 severe, ≥12 impending respiratory failure.
Croup severity categories and what they mean for treatment
Mild (Westley 0-2)
Occasional barky cough, no stridor at rest, no or minimal retractions, and a child who is comfortable and playful when calm. Managed with a single dose of oral dexamethasone; can generally go home after a period of observation, and nebulized epinephrine is not required.
Moderate (Westley 3-5)
Frequent barking cough, stridor audible at rest without significant agitation, and mild-to-moderate retractions, with little or no distress at rest. Managed with oral dexamethasone; nebulized epinephrine is added if stridor at rest or distress is present, followed by an observation period before discharge.
Severe (Westley 6-11)
Stridor at rest, marked retractions, and significant distress or agitation, with decreased air entry. Requires nebulized epinephrine plus dexamethasone, oxygen if hypoxic, emergency department management, and a longer observation period; hospitalization is often required.
Impending respiratory failure (Westley ≥12)
Lethargy or decreased level of consciousness, pallor or cyanosis, and markedly decreased air entry with reduced respiratory effort — a true airway emergency. Requires immediate escalation, continuous monitoring, repeat or back-to-back nebulized epinephrine only with cardiac monitoring, and preparation for advanced airway management in a monitored/ICU setting.
Treatment Targets
- Relieve upper-airway obstruction and reduce the work of breathing.
- Shorten the duration and severity of stridor, cough, and retractions.
- Avoid unnecessary intubation and hospitalization.
- Minimize anxiety and agitation in the child — agitation worsens turbulent airflow through the narrowed airway and can itself precipitate progression — and reduce caregiver distress.
- Correctly identify and manage red-flag mimics (epiglottitis, bacterial tracheitis, foreign body aspiration) rather than treating one of them as routine croup.
- Prevent avoidable return visits by ensuring effective initial dosing and clear caregiver counselling on red-flag recognition.
Choose Initial Treatment
Site of care
Mild croup can be managed at home or in an outpatient/office setting after a single dose of oral dexamethasone and a brief period of observation.
Moderate or severe croup should be referred to an emergency department for treatment (dexamethasone plus nebulized epinephrine as indicated) and observation.
Corticosteroid
1st line, all severities a single dose of oral dexamethasone 0.6 mg/kg (maximum 10 mg) is the preferred standard dose for every child diagnosed with croup, regardless of severity — current evidence shows it reduces croup score more at 24 hours than the lower 0.15 mg/kg dose, although the two doses do not clearly differ in the need for additional treatment.[2]
Alternative dose, particularly for mild croup dexamethasone 0.15 mg/kg PO single dose is a reasonable lower-dose option supported by dose-ranging trials, especially when minimizing corticosteroid exposure is a priority.[7]
Oral administration is preferred over intramuscular or intravenous dosing whenever the child can tolerate it — it is equally effective and less distressing. Special situation — vomiting or too distressed for oral dosing use parenteral (IM/IV) dexamethasone or nebulized budesonide instead.
Nebulized epinephrine
Add nebulized L-epinephrine for any child with stridor at rest, significant distress, or severe croup — give alongside, not instead of, dexamethasone, and observe for a minimum of 2-3 hours after the dose before considering discharge, given the drug's roughly 1-2 hour duration of effect.[8]
Special situation — near respiratory failure back-to-back nebulized epinephrine doses may be used, but only with continuous cardiac monitoring and immediate pediatric critical care involvement, given a reported case of ventricular tachycardia and myocardial infarction after repeated dosing within a short interval.
What not to use
Do not use inhaled beta2-agonists (e.g., salbutamol) — the upper airway has no smooth muscle for these drugs to act on, and there is no evidence of benefit.
Do not use antitussives or decongestants — there is no rational basis for benefit, and Health Canada specifically advises against these products in children under 6 years of age.[9]
Do not use antibiotics for typical viral croup — reserve broad-spectrum antibiotics, chosen under specialist/ICU direction, for the rare case of confirmed or strongly suspected bacterial tracheitis or epiglottitis.
Non-Pharmacologic Treatment
- Keep the child calm, ideally held upright on a caregiver's lap in a calm, reassuring environment — agitation and crying increase turbulent airflow through the narrowed airway and can transiently worsen stridor and distress; minimize unnecessary examinations, needle sticks, or separation from the caregiver.
- A brief period of exposure to cool or cold outdoor air (dressed warmly, never left unattended) is a reasonable, low-risk adjunct — a randomized trial found a higher proportion of children improved after cold outdoor air exposure than after room-temperature exposure.[10]
- Humidified air, bedside mist, and mist tents have not been shown to reduce respiratory distress in croup and should not be relied on as therapy — a wet, cold, enclosed mist tent that separates a child from their caregiver can itself provoke anxiety and agitation, which is counterproductive.[11]
- Oxygen, when needed for hypoxia or significant respiratory distress, is given alongside dexamethasone and epinephrine, never as a substitute for them; "blow-by" oxygen (a hose held near the child's face) is often best tolerated, and oxygen should never be forced on an agitated child.
- Helium-oxygen (heliox) mixtures may be considered as an adjunct in severe croup at centres equipped to deliver and monitor it, but current evidence is too limited to support routine or general use.[12]
- Ensure adequate oral fluid intake for hydration and comfort; offer antipyretic/analgesic dosing (see Pharmacologic Treatment Options) for fever or throat discomfort.
Special Populations
Pregnancy and breastfeeding
Not applicable — croup is a pediatric condition and does not occur in pregnant or breastfeeding adults; no pregnancy/lactation-specific dosing considerations apply to this chapter.
Infants under 3 months
Croup is uncommon in this age group. Stridor in a young infant should prompt evaluation for an underlying structural airway abnormality (e.g., laryngomalacia, subglottic stenosis, vascular ring) rather than being assumed to be viral croup — refer for further assessment.
Recurrent (spasmodic) croup or croup outside the typical age range
Three or more episodes, or croup presenting outside the typical 6-month-to-3-year window (especially in older children or with onset before 3 months), should prompt referral for otolaryngology evaluation to rule out an underlying structural airway lesion such as subglottic stenosis or a subglottic hemangioma.
Underlying chronic airway, cardiac, or immunocompromising conditions
Children with Down syndrome, other conditions predisposing to baseline airway narrowing, chronic lung or cardiac disease, or immunocompromise have a lower threshold for hospitalization and closer monitoring, since croup can progress more quickly or severely in these children.
Concurrent varicella (chickenpox)
A single dose of corticosteroid for croup does not need to be withheld from a child with active or recent varicella infection — recent corticosteroid use has not been shown to increase the risk of complicated varicella in otherwise immunocompetent children in case-control data.[13]
Renal / hepatic impairment
No dose adjustment is required for a single dose of dexamethasone. Use caution with repeated dosing in significant hepatic impairment; renal impairment does not require dose adjustment for the corticosteroids or nebulized epinephrine used in croup.
Monitoring & Follow-Up
Reassess a child who receives nebulized epinephrine at around 20-30 minutes (near peak effect) and again before discharge, at a minimum of 2-3 hours after the dose, to confirm stridor is not present at rest and the child is tolerating oral fluids. A child who received oral dexamethasone alone for mild croup can generally be discharged after a shorter period of observation once comfortable, particularly if this is not the first assessment for the episode.
Give caregivers a clear expected course (symptoms often peak over the first 2-3 nights before improving, with full resolution typically by about a week) and explicit red-flag return instructions rather than only a vague "come back if it gets worse."
No routine follow-up visit or repeat testing is needed after an uncomplicated, resolved episode. Refer for otolaryngology assessment if the child has 3 or more discrete croup episodes or croup outside the typical age range.
Common Errors to Avoid
- Withholding dexamethasone from a child with mild croup on the assumption that corticosteroids are only for moderate-severe disease — current evidence supports benefit across the full severity spectrum.
- Relying on humidified air, cool mist, or a mist tent as primary therapy — not supported by current evidence, and a mist tent can increase a child's distress by separating them from their caregiver in a cold, wet, enclosed space.
- Discharging a child immediately after nebulized epinephrine without an adequate observation period.
- Using inhaled beta2-agonists (e.g., salbutamol) for croup — the upper airway has no smooth muscle for these drugs to act on.
- Giving over-the-counter cough and cold products (antitussives, decongestants) to a child under 6 years of age.
- Attempting an oropharyngeal examination, IV access, or laying a child supine when epiglottitis is suspected — this can precipitate complete airway obstruction.
- Assessing severity only while the child is calm — stridor and retractions are most apparent during agitation or crying, and a snapshot taken only at rest can underestimate true severity.
- Missing a cue (recurrent episodes, atypical age, poor response to therapy) to investigate for an underlying structural airway lesion.
- Routinely combining nebulized budesonide with oral dexamethasone — no added clinical benefit has been shown, only added cost and treatment burden.
- Using antibiotics for typical viral croup.
Clinical Decision Algorithm
Drug Tables
How to use this table: Doses are adult doses and require patient-specific confirmation (renal/hepatic function, weight, allergy history). Pediatric dosing is weight-based per the current product monograph unless stated. Drug pricing is intentionally omitted. Select any drug name to open its complete Pharmasist Drug Database page.
Corticosteroids
Mainstay of croup therapy for every severity level — the single most important pharmacologic decision in croup management.
| Drug | Dosage | Adverse effects | Comments |
|---|---|---|---|
| Dexamethasone | Standard dose (preferred): 0.6 mg/kg PO/IM/IV single dose, maximum 10 mg Lower-dose alternative: 0.15 mg/kg PO single dose — an accepted alternative, particularly for mild croup Supplemental dosing: May repeat in 6-24 hours if needed; total maximum 0.6 mg/kg/day or 10 mg/day, whichever is less | Generally well tolerated as a single dose; transient hyperglycemia or behavioural change possible | Oral route preferred over IM/IV — equally effective and less distressing for the child. No evidence that multiple doses add benefit over a single dose for most children.[2] |
| Budesonide, nebulized | Standard dose: 2 mg (4 mL of 0.5 mg/mL nebulizer suspension) Repeat dosing: May repeat in 6-24 hours if needed | Local throat/airway irritation, cough | Equivalent efficacy to oral dexamethasone but more costly. Do not add routinely to oral dexamethasone — no additional benefit has been shown. Preferred when oral dosing is not tolerated (e.g., vomiting), or alongside epinephrine in severe croup. |
Adrenergic agonists
For moderate-to-severe croup with stridor at rest or significant distress — always given alongside, not instead of, dexamethasone.
| Drug | Dosage | Adverse effects | Comments |
|---|---|---|---|
| Epinephrine (L-epinephrine 1:1000), nebulized | Standard dose: 5 mL of 1:1000 (1 mg/mL) solution via nebulizer — same single-sized dose regardless of age or weight Repeat/back-to-back dosing: Reserve for near-respiratory-failure only, with continuous cardiac monitoring and pediatric critical care involvement | Tachycardia, tremor, pallor, hypertension | Onset within about 10 minutes; effect lasts roughly 1-2 hours. Observe at least 2-3 hours post-dose before discharge. Racemic epinephrine is no longer available in Canada — L-epinephrine is equally effective and safe.[8] |
Analgesics / antipyretics
Comfort measures only — neither treats the underlying airway obstruction.
| Drug | Dosage | Adverse effects | Comments |
|---|---|---|---|
| Acetaminophen | Dosing: 10-15 mg/kg PO/PR every 4-6 hours as needed, per current weight-based product dosing | Hepatotoxicity with overdose or chronic excess dosing | Comfort measure for fever or throat discomfort; not a substitute for dexamethasone. |
| Ibuprofen | Dosing: 5-10 mg/kg PO every 6-8 hours as needed, per current weight-based product dosing | GI upset; avoid with significant dehydration or renal concern | Alternative comfort measure; avoid in infants under 6 months. |
Not effective / not recommended
These agents are specifically not part of croup management and should not be used:
- Inhaled beta2-agonists (e.g., salbutamol) — the upper airway contains no smooth muscle for these drugs to act on; no trial evidence supports benefit.
- Antitussives and decongestants — no rational basis for benefit, and specifically discouraged by Health Canada in children under 6 years of age.
- Routine antibiotics — croup is viral. Reserve broad-spectrum IV antibiotics, chosen and dosed under specialist/ICU direction, for confirmed or strongly suspected bacterial tracheitis or epiglottitis, which are managed as airway emergencies outside the scope of this table.
- Helium-oxygen (heliox) — may be considered as an adjunct in severe croup at centres able to deliver and monitor it, but current evidence is too limited to support routine use.
References
- Croup in children — CMAJ (Bjornson CL, Johnson DW). CMAJ 2013;185(15):1317-1323
- Glucocorticoids for croup in children — Cochrane Database of Systematic Reviews (Aregbesola A, Tam CM, Kothari A, et al.). Cochrane Database Syst Rev 2023;1(1):CD001955
- Croup: Diagnosis and Management — American Family Physician (Smith DK, McDermott AJ, Sullivan JF). Am Fam Physician 2018;97(9):575-580
- Review of epiglottitis in the post Haemophilus influenzae type-b vaccine era — ANZ Journal of Surgery (Baird SM, Marsh PA, Campbell MC, et al.). ANZ J Surg 2018;88(11):1135-1140
- Bacterial tracheitis — Pediatrics in Review (Kuo CY, Parikh SR). Pediatr Rev 2014;35(11):497-499
- Nebulized racemic epinephrine by IPPB for the treatment of croup: a double-blind study — American Journal of Diseases of Children (Westley CR, Cotton EK, Brooks JG). Am J Dis Child 1978;132(5):484-487
- Oral dexamethasone in the treatment of croup: 0.15 mg/kg versus 0.3 mg/kg versus 0.6 mg/kg — Pediatric Pulmonology (Geelhoed GC, Macdonald WB). Pediatr Pulmonol 1995;20(6):362-368
- Nebulized epinephrine for croup in children — Cochrane Database of Systematic Reviews (Bjornson C, Russell K, Vandermeer B, et al.). Cochrane Database Syst Rev 2013;(10):CD006619
- Concerns about children's medication: avoiding cough and cold medications — Health Canada, Government of Canada. Government of Canada, Health Canada
- Outdoor Cold Air Versus Room Temperature Exposure for Croup Symptoms: A Randomized Controlled Trial — Pediatrics (Siebert JN, Salomon C, Taddeo I, et al.). Pediatrics 2023;152(3):e2023061365
- Humidified air inhalation for treating croup — Cochrane Database of Systematic Reviews (Moore M, Little P). Cochrane Database Syst Rev 2006;(3):CD002870
- Heliox for croup in children — Cochrane Database of Systematic Reviews (Moraa I, Sturman N, McGuire TM, van Driel ML). Cochrane Database Syst Rev 2021;8(8):CD006822
- Recent corticosteroid use and the risk of complicated varicella in otherwise immunocompetent children — Archives of Pediatrics & Adolescent Medicine (Patel H, Macarthur C, Johnson D, et al.). Arch Pediatr Adolesc Med 1996;150(4):409-414
Professional reference only. Apply clinical judgment and verify patient-specific decisions against current authoritative guidance and product information.