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Overview

What Is Croup?

Croup is usually a viral infection that causes swelling around the voice box (larynx) and windpipe (trachea). It most often affects young children because their airways are small. This swelling causes the characteristic barking croup cough and may lead to noisy breathing, especially when breathing in.

Emergency Warning Signs

Emergency Warning Signs of Croup

Call emergency services

Emergency breathing signs

Call emergency services for severe or rapidly worsening breathing difficulty, especially if a child has stridor while resting or looks exhausted. These signs can mean the airway is becoming dangerously narrow.

  • Stridor, or a harsh noisy sound, while the child is resting.
  • The ribs or neck pulling in with each breath.
  • Blue or gray lips, face, or skin.
  • Pauses in breathing.
  • Extreme sleepiness, weakness, or exhaustion.
  • Drooling or inability to swallow.
  • Inability to speak or cry normally.
  • Rapidly worsening symptoms.

Keep the child upright and as calm as possible while seeking help. Do not force food or drink, and do not drive yourself if the child is struggling to breathe; call emergency services instead.

Symptoms

Croup Symptoms

  • A barking cough.
  • A hoarse or raspy voice.
  • Noisy breathing when breathing in (stridor).
  • Runny nose or other cold symptoms.
  • Fever.
  • Symptoms that become worse at night.

How It Spreads

How Croup Spreads

The viruses that cause croup spread through respiratory droplets, close contact, and contaminated hands or surfaces. The virus is contagious; croup symptoms are the body’s response to swelling in the upper airway. A child can spread the virus before or during early symptoms, even though not everyone who catches it develops croup.

StageWhat to know
Before symptomsSome respiratory viruses can spread before symptoms are noticeable.
Early illnessContagiousness is usually greatest early in the illness, when cold symptoms are active.
After improvementThe risk generally declines as symptoms improve, but useful precautions include handwashing and avoiding close contact while the child remains ill.
  • Wash hands often with soap and water, especially after wiping a nose or covering a cough.
  • Cover coughs and sneezes with a tissue or the elbow, then dispose of tissues promptly.
  • Clean frequently touched surfaces such as doorknobs, phones, and shared toys.
  • Keep a child home from school or group activities while ill and follow local guidance for returning.
  • Limit close contact with infants, older adults, and people with conditions that increase the risk of severe respiratory illness.

Risk Factors

Croup Risk Factors

  • Young age, particularly the preschool years, because the upper airway is smaller.
  • Exposure to respiratory viruses through household, school, or childcare contact.
  • Fall or winter circulation of respiratory viruses.
  • A naturally narrow upper airway.
  • Having had croup before, because it can recur.
  • A condition that makes breathing more difficult if airway swelling develops.

Croup is most common in young children. Adults can rarely develop a croup-like illness, but significant noisy breathing in an adult needs medical assessment because other airway problems may be responsible.

Complications

Croup Complications

Most cases of croup are mild and improve with supportive care. However, swelling can occasionally cause significant airway narrowing and reduced oxygen, especially in very young children.

  • Severe upper-airway obstruction can make it difficult for air to move into the lungs.
  • Dehydration can occur when breathing is difficult or the child is drinking much less than usual.
  • Respiratory failure can develop if severe airway narrowing is not treated promptly.
  • An uncommon bacterial superinfection can cause a more serious illness requiring urgent medical care.

Safety reminder

Breathing problems can worsen quickly

Rapidly worsening breathing, exhaustion, or bluish or gray skin requires emergency care rather than home observation.

Diagnosis

How Croup Is Diagnosed

Clinicians usually diagnose croup from the history and physical examination. They ask about the barking cough, hoarseness, stridor, when symptoms started and how they change, and any fever. They also check the child’s breathing rate, temperature, oxygen level when appropriate, and signs of increased work of breathing.

When Additional Tests May Be Needed

Additional tests may be considered when the presentation is unusual, another airway problem is possible, or the illness is severe. Routine throat swabs, blood tests, and imaging are not usually needed for typical croup. Clinicians avoid upsetting children when possible because crying can temporarily worsen noisy breathing.

Treatment & Management

Croup Treatment and Management

MILD ILLNESS

Keep the child calm and upright, offer frequent fluids, provide comfort for fever as directed, and monitor breathing closely. Seek medical advice if symptoms worsen or the child cannot drink.

MODERATE OR SEVERE ILLNESS

A clinician may give a corticosteroid to reduce airway swelling and nebulized epinephrine for more significant breathing difficulty. Observation, oxygen, or hospital care may be needed if symptoms do not settle or breathing support is required.

  • Keep the child calm and upright, since crying and agitation can make noisy breathing worse.
  • Offer small, frequent amounts of fluid if the child can swallow safely.
  • Follow the clinician’s instructions for corticosteroids or other medicines.
  • Avoid tobacco smoke and other airway irritants.
  • Do not use antibiotics or cough medicines unless a clinician specifically directs you to do so.

Prevention

Can Croup Be Prevented?

  • Clean hands regularly with soap and water or an appropriate hand sanitizer.
  • Cover coughs and sneezes and teach children to avoid touching their face.
  • Avoid close contact with people who have active respiratory symptoms.
  • Clean shared toys, handles, and other frequently touched surfaces.
  • Improve indoor air quality with ventilation and avoid tobacco smoke.
  • Keep routine vaccinations current to reduce the risk of preventable respiratory infections.

There is no vaccine specifically for croup because several different viruses can cause it. However, preventing respiratory infections can lower the risk of croup and reduce spread to others, including newborns and other higher-risk household members.

Outlook and Prognosis

How Long Does Croup Last?

Croup symptoms often worsen at night, peak within the first few days, and improve over several days. A mild cough or hoarseness may last longer after the noisy breathing settles. Recurrent, prolonged, or worsening symptoms need medical review.

Time periodExpected pattern
First nightThe barking cough or noisy breathing may begin suddenly or become more noticeable at night.
Next few daysSymptoms commonly reach their peak early and then begin to improve, although the pattern varies.
After improvementA mild cough or hoarseness can linger; contact a clinician if symptoms persist, recur often, or become worse.

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