What a croup cough sounds like
- Barking cough: a harsh, loud cough often described as a seal or a dog barking.
- Hoarse voice or cry: from swelling of the voice box.
- Stridor: a high-pitched, harsh, whistling sound when breathing in, especially when upset.
- Worse at night: symptoms often start or worsen in the evening and at night.
Recording a short video of the cough and breathing can help a doctor assess your child.
What causes croup
Croup is usually caused by viruses, most commonly parainfluenza viruses, and also by respiratory syncytial virus (RSV), flu, COVID-19 and others. The infection causes swelling below the vocal cords. Because young children have narrow airways, even small amounts of swelling cause noisy breathing.
Croup is most common between 6 months and 3 years of age and can recur in some children.
How croup usually progresses
- Day 1 to 2: cold symptoms such as a runny nose, mild fever and sore throat.
- Day 2 to 3: barking cough and hoarse voice appear, often worse at night.
- Most children improve after 48 hours.
- The cough may linger for up to a week or more.
Caring for your child at home
- Keep your child calm and comfortable; crying makes breathing harder.
- Hold them upright on your lap.
- Offer plenty of fluids.
- Give paracetamol or ibuprofen for fever or discomfort.
- Stay with your child at night and check on them regularly.
- Do not use steam or hot water, which can cause burns and is not effective.
Medical treatment
A doctor may give a single dose of oral steroid, usually dexamethasone, which reduces airway swelling and improves symptoms within a few hours, and reduces the need for hospital care. In severe croup, children are treated in hospital with nebulised adrenaline and oxygen, and monitored closely.
Antibiotics do not help croup, because it is caused by viruses.
Mild, moderate and severe croup
- Mild: barking cough but no stridor or breathing difficulty at rest; managed at home.
- Moderate: stridor and some chest wall drawing in at rest, but the child is not distressed; needs medical assessment.
- Severe: stridor at rest, marked breathing difficulty, agitation or drowsiness; needs emergency care.
Conditions that can look like croup
- Epiglottitis: rare since vaccination; sudden high fever, drooling, difficulty swallowing and sitting forward; an emergency.
- Bacterial tracheitis: a child who seems very unwell with high fever.
- Inhaled foreign object: sudden coughing or choking without cold symptoms.
- Allergic reaction: swelling of the lips, face or throat.
- Recurrent croup: may need ENT assessment of the airway.
Preventing spread
The viruses that cause croup spread through coughs, sneezes and contaminated hands and surfaces. Regular handwashing, cleaning toys and surfaces, and keeping children with fever at home help reduce spread. Routine vaccinations protect against some serious causes of breathing problems.
When croup keeps coming back
Some children have several episodes of croup, sometimes without a clear viral illness, known as recurrent or spasmodic croup. It can be linked to allergies, reflux or a narrowing of the airway. Children with frequent or severe episodes, or croup under 6 months of age, may need assessment by an ENT specialist.
See also wet cough and dry cough at night.
Getting through the night
- Keep your child’s room comfortably cool rather than hot.
- Sleep near your child, or have them sleep in your room, so you can hear their breathing.
- Sit them up and comfort them if they wake coughing.
- Some parents find that a few minutes of cool night air helps, though evidence is limited.
- Avoid cough medicines, which do not help croup.
When to call for help
- Stridor when the child is calm or at rest.
- Struggling to breathe, with the skin between the ribs or at the neck sucking in.
- Pale, blue or grey skin or lips.
- Drowsiness, unusual floppiness or confusion.
- Drooling or inability to swallow.
- High fever or a child who seems very unwell.
Call emergency services for severe breathing difficulty or blue lips.
Key points to remember
- Croup causes a barking, seal-like cough and hoarse voice in young children.
- It is usually viral, worse at night and improves within a few days.
- A single dose of steroid helps; steam is not recommended.
- Stridor at rest or breathing difficulty needs urgent care.
Questions about croup
These answers are general information and do not replace an examination or individual medical advice.
What does croup sound like?
A harsh, barking cough like a seal, sometimes with a high-pitched noise when breathing in.
Is croup contagious?
Yes. The viruses that cause it spread easily.
How long does croup last?
Most children improve within 48 hours and recover within a week.
Why is croup worse at night?
Natural changes in breathing and hormones at night, plus lying down, make symptoms worse.
Can adults get croup?
It is rare in adults, whose larger airways cope better with swelling.
Does cold air help croup?
Some parents find it helps, but evidence is limited. Keeping the child calm matters most.
When should I take my child to hospital with croup?
If there is noisy breathing at rest, difficulty breathing, blue lips or drowsiness.
Sources
This guide is for general information and does not replace medical advice. How a problem is diagnosed and treated depends on your examination and medical history. If you think you have an emergency, contact your local emergency services.