Croup in Adults: Barking Cough and Stridor Explained

What causes the barking cough and stridor in croup?

Croup (laryngotracheitis) is caused by viral infection — most often parainfluenza viruses — that causes swelling in the subglottic airway, the narrow passage just below the vocal cords 1Ref 1Kadam SJ, Daley SF, Carr B (2025).Croup.Parainfluenza viral cause of croup, subglottic swelling mechanism producing barking cough and inspiratory stridor, corticosteroid and nebulized epinephrine treatment. In children, this passage is small, so even modest swelling produces the dramatic seal-bark cough and the rasping sound of air squeezed past swollen tissue (stridor). In adults, the airway is larger, so the same degree of viral swelling causes less obstruction — which is why adult croup is milder and less common as an acute emergency.

The characteristic sound is a barking or seal-like cough, hoarseness, and inspiratory stridor — the noise occurs during inhalation, not exhalation. Symptoms often worsen at night 1Ref 1Kadam SJ, Daley SF, Carr B (2025).Croup.Parainfluenza viral cause of croup, subglottic swelling mechanism producing barking cough and inspiratory stridor, corticosteroid and nebulized epinephrine treatment.

How is adult croup different from croup in children?

In adults: - The absolute airway diameter is larger, so swelling causes proportionally less narrowing - Croup rarely progresses to life-threatening respiratory distress in adults - Adults may present with a prolonged barking or brassy cough without obvious stridor at rest - The illness is sometimes confused with a severe laryngitis or bronchitis

Treatment principles are similar to those in children: corticosteroids (such as dexamethasone) reduce airway swelling, nebulized epinephrine can rapidly reduce mucosal edema when needed, and supportive care with humidified air and hydration is standard 1Ref 1Kadam SJ, Daley SF, Carr B (2025).Croup.Parainfluenza viral cause of croup, subglottic swelling mechanism producing barking cough and inspiratory stridor, corticosteroid and nebulized epinephrine treatment3Ref 3American Academy of Family Physicians (2026).Croup: Rapid Evidence Review.Corticosteroid treatment as first-line for croup including dexamethasone; management principles applicable to adults. Most adult croup resolves with outpatient treatment.

What other conditions cause stridor or barking cough in adults?

This is the most important clinical question, because some mimics of croup in adults are emergencies:

Epiglottitis — infection of the epiglottis (the flap that covers the airway during swallowing) is rare in vaccinated populations but has become proportionally more common in adults than children since Hib vaccination. Adults typically present with severe sore throat, drooling, difficulty swallowing, a muffled or 'hot-potato' voice, and may or may not have stridor. They often appear toxic. Epiglottitis can close the airway rapidly and is a medical emergency 2Ref 2Sanyaolu A, Okorie C, Younis MZ (2024).Epiglottitis.Epiglottitis as a life-threatening upper airway emergency in adults; post-Hib shift toward adult predominance; clinical features distinguishing epiglottitis from croup.

Angioedema — allergic swelling of the throat and airway produces stridor and can close the airway within minutes. Angioedema from ACE inhibitor medications may develop without a clear allergic trigger.

Vocal cord dysfunction (paradoxical vocal fold movement) — the vocal cords close abnormally during inhalation, producing stridor that mimics upper airway obstruction. It is often triggered by exercise, anxiety, or irritants and is not life-threatening.

Foreign body aspiration — uncommon but should be considered when stridor is sudden-onset without a viral prodrome.

Laryngeal mass or tumor — slow-growing lesions produce progressive hoarseness and eventually stridor; generally not acute in onset.

When does adult stridor need emergency evaluation?

Any adult with stridor who appears to be in respiratory distress — using accessory muscles to breathe, unable to speak in full sentences, drooling, leaning forward, or looking anxious and pale — needs emergency evaluation immediately. These signs suggest severe airway compromise.

Epiglottitis and angioedema in particular can deteriorate rapidly. Attempting to examine the throat of a patient with suspected epiglottitis outside a setting where the airway can be secured is dangerous.

What should I expect at a clinician visit for a barking cough?

If you have a barking, hoarse cough without respiratory distress, a primary care clinician can evaluate you. They will assess vital signs, listen to the quality of breathing, and examine the throat. If the presentation is consistent with uncomplicated viral croup or laryngitis, treatment with a corticosteroid (to reduce swelling) and supportive care is typical. If there is any concern for epiglottitis or another serious cause, they will direct you to an emergency setting.

A Gale primary care clinician can evaluate you for barking cough and stridor and help determine urgency.