Is croup (laryngitis) contagious?

Yes. The virus that causes croup (mainly parainfluenza) spreads through respiratory droplets. A child is contagious while symptomatic, usually for 3 to 7 days. However, not every child who catches the virus develops croup — many will only have a common cold.

What should I do during a croup attack at night?

Stay calm and comfort your child, as crying worsens stridor. Take them to breathe cool, fresh air for 10-15 minutes (near an open window or balcony). If stridor does not improve at rest, there is difficulty breathing, or lips turn blue, go to the emergency room immediately.

Does nebulization with saline help croup?

Simple saline nebulization has limited benefit for croup. Effective treatment for moderate to severe croup is done in the ER with nebulized epinephrine and oral corticosteroid (dexamethasone). At home, cool and humid air may relieve mild symptoms.

At what age is croup most dangerous?

Croup is most common and potentially more serious between 6 months and 3 years of age, because the larynx is anatomically narrower in this age group. After age 6, episodes are rare and generally milder, as the airway is larger.

Can croup turn into pneumonia?

They are different conditions. Croup affects the larynx and trachea (upper airways), while pneumonia affects the lungs. The same virus can sometimes cause lower airway infection, but croup itself does not turn into pneumonia. If your child worsens with high fever and breathing difficulty, seek medical evaluation.

Childhood Laryngitis (Croup): Symptoms, Treatment, and When to Go to the ER

Your child woke up in the middle of the night with a barking cough that sounds like a seal and difficulty breathing? It could be acute laryngitis, also known as croup. This condition is frightening for parents, but in most cases it is self-limiting and can be managed at home. In this guide, we explain how to identify croup, what to do during a crisis, when to go to the emergency room, and how to prevent future episodes. If your child has respiratory symptoms, also learn when to take your child to the pediatrician.

What Is Croup (Laryngitis)?

Croup is a viral infection of the larynx and trachea (the upper airways) that causes swelling below the vocal cords. This narrowing produces the characteristic barking cough and a harsh, high-pitched breathing sound called stridor. It is called "laringite" in Brazilian Portuguese, which you may hear at Brazilian hospitals or clinics.

The parainfluenza virus causes approximately 75% of croup cases, though other viruses (RSV, influenza, adenovirus) can also trigger it. Croup is most common during cold and flu season in Sao Paulo (typically April through September).

Why Children Are More Affected

Children between 6 months and 3 years are most vulnerable because their larynx is anatomically narrower. Even mild swelling significantly reduces airflow. After age 6, the airway is larger, and croup episodes become rare and much milder. This is also why wheezing and respiratory symptoms tend to be more concerning in younger children.

Recognizing Croup: Key Symptoms

Croup typically starts as a regular cold with mild fever, runny nose, and cough. Then, usually at night, the characteristic symptoms appear:

Classic Croup Symptoms

Barking cough — sounds like a seal or a dog
Stridor — harsh, high-pitched sound when breathing in
Hoarse voice — the child sounds raspy
Worse at night — symptoms typically peak between 10 PM and 4 AM

Associated Symptoms

Low-grade fever (usually below 39 C / 102.2 F)
Runny nose that started 1-2 days before
Agitation and crying (which worsen symptoms)
Symptoms last 3-7 days, worst on days 2-3

Severity Classification: Mild, Moderate, and Severe

Feature	Mild	Moderate	Severe
Barking cough	Occasional	Frequent	Frequent
Stridor	Only when agitated	At rest	At rest, loud
Breathing effort	None	Mild chest retractions	Significant retractions
Child's behavior	Normal, playful	Restless, agitated	Anxious or lethargic
Action	Manage at home	See pediatrician or ER	ER immediately

Worried about your child's cough?

Schedule a respiratory evaluation with Dr. Paula in Itaim Bibi, Sao Paulo. Bilingual care for expat families.

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What to Do During a Croup Attack at Home

Step-by-Step: Managing Mild Croup at Home

1Stay calm and comfort your child. Crying and agitation worsen stridor significantly. Hold your child upright in a comfortable position.

2Expose to cool, fresh air. Open a window or take your child to a balcony for 10-15 minutes. In Sao Paulo, night air is typically cool enough, especially during the winter months (June-August).

3Keep the head elevated. Have your child sit upright or prop up the head of the bed. This reduces swelling in the airway.

4Offer fluids. Small sips of cool water or breast milk help keep the child hydrated and calm.

5Manage fever if present. Use age-appropriate doses of acetaminophen (paracetamol) or ibuprofen.

Emergency Treatment at the Hospital

For moderate to severe croup, treatment at the ER (pronto-socorro in Portuguese) includes:

Oral Dexamethasone (Corticosteroid)

A single dose reduces airway swelling. It is the cornerstone of croup treatment and works within 2-4 hours. The benefit lasts 24-48 hours.

Nebulized Epinephrine (Adrenaline)

Used for severe stridor to rapidly reduce swelling. Works within minutes but the effect lasts only 1-2 hours. The child must be observed for rebound symptoms.

For Expat Families: Emergency Care in Sao Paulo

If your child needs emergency care for croup in Sao Paulo, the main private hospitals with English-speaking staff include Albert Einstein, Sirio-Libanes, and Sabara Children's Hospital. You can also contact Dr. Paula via WhatsApp for guidance. Learn more about navigating pediatric care in Brazil as an expat.

When to Go to the Emergency Room

Go to the ER IMMEDIATELY If You Notice

Stridor at rest that does not improve with cool air and calming

Visible breathing difficulty — ribs pulling in, nostril flaring, chest sinking

Blue or pale lips/skin (cyanosis) — a sign of inadequate oxygen

Drooling or difficulty swallowing — may indicate epiglottitis, a more serious condition

Extreme lethargy or anxiety — the child appears very unwell

Prevention

There is no specific vaccine against croup, but several measures help reduce the risk. Many overlap with prevention strategies for other respiratory conditions like bronchiolitis and chronic cough:

Frequent hand washing — the most effective prevention

Keep vaccinations up to date (influenza vaccine protects against one cause of croup)

Avoid smoke exposure (tobacco, incense, pollution)

Teach children to cough into their elbow and avoid sharing utensils

Looking for a bilingual pediatrician in Sao Paulo?

Dr. Paula provides thorough evaluations with 40-60 minute consultations and WhatsApp follow-up.

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Key Takeaways for Parents

Croup is common and usually resolves within 3-7 days with home management

Cool, fresh air is the best first-line treatment at home

Stridor at rest requires medical evaluation — do not delay

A single dose of corticosteroid is highly effective and is the standard hospital treatment

Keep calm— your child's anxiety worsens the symptoms

If your child has recurrent croup episodes or you are unsure whether their cough is croup, schedule a consultation with an English-speaking pediatrician for a proper evaluation. Understanding the difference between croup and conditions like tonsillitis or asthma is essential for the right treatment approach.