Quick answer. Croup is a common viral infection that swells the upper airway in young children, causing a distinctive barking cough and a harsh sound on breathing in (stridor). Most cases are mild and settle at home, but if a child has stridor at rest, is struggling to breathe or has blue lips, call 995 immediately.
Not sure which best gp clinic you need?
Message our care team on WhatsApp. Tell us what’s going on and we’ll help you find the right best gp clinic — free, with no obligation.
Chat with our care team on WhatsAppNot sure who to see? Find the right specialist →
In a medical emergency, or for severe or sudden symptoms such as breathing difficulty, chest pain, fainting or stroke signs, call 995 immediately.
Croup is one of the more alarming-sounding childhood illnesses, mostly because of its hallmark barking, seal-like cough that often strikes at night. In Singapore it is a frequent reason parents bring a toddler to see a doctor. The good news is that the great majority of croup cases are mild, caused by common viruses, and improve within a few days. Knowing what croup is, and which signs mean a child needs urgent care, helps parents respond calmly.
This guide covers what croup is, the symptoms and barking cough that define it, why it happens, how doctors assess it and how it is treated. Croup mainly affects children between about six months and three years, whose airways are small enough that even mild swelling causes a noticeable noise. We also explain clearly when croup becomes a breathing emergency.
At a glance
| Severity | What you might see | What to do |
|---|---|---|
| Mild | Barking cough, no stridor at rest, child playful | Comfort and home care; see GP if unsure |
| Moderate | Stridor and chest pulling-in when active or upset | See a doctor the same day |
| Severe | Stridor at rest, fast breathing, distress | Go to A&E urgently |
| Emergency | Struggling to breathe, blue lips, drowsy, drooling | Call 995 now |
| Improving | Cough easing, breathing quiet, feeding well | Continue home care, finish recovery |
What is croup?
Croup is swelling of the upper airway, the voice box (larynx) and windpipe (trachea), usually triggered by a virus. The swelling narrows the airway, which produces the characteristic barking cough and the harsh, high-pitched sound when breathing in known as stridor. A child’s voice or cry may also sound hoarse.
It is most common in children aged about six months to three years, because their airways are naturally small, so a little swelling makes a big difference to airflow and noise. Croup is common in Singapore, tends to come on or worsen at night, and is usually worse for one or two nights before settling over several days.
Symptoms & signs
Croup often starts like a common cold, then develops its distinctive features. Look out for:
- A barking, seal-like cough, often suddenly worse at night
- A hoarse voice or cry
- Stridor, a harsh rasping sound when breathing in
- A runny nose, mild fever and sore throat in the days before
- Symptoms that flare in the evening and ease during the day
In mild croup the child is otherwise alert, playful and feeding. The signs that matter most are how the child is breathing and behaving at rest, not just how dramatic the cough sounds.
Causes & risk factors
Croup is almost always caused by a virus that spreads through coughs, sneezes and contaminated hands and surfaces. Contributing factors include:
- Viruses: parainfluenza viruses are the most common cause, but other respiratory viruses (including influenza and RSV) can trigger it too.
- Age: children aged six months to three years are most affected because of their small airways.
- Season: cases cluster when respiratory viruses circulate, and croup classically worsens at night.
- Close contact: childcare and household contact with other unwell children raises exposure.
Because it is viral, antibiotics do not help ordinary croup.
How croup is diagnosed
Croup is usually diagnosed clinically, meaning the doctor recognises it from the typical barking cough and breathing sounds together with the child’s age. Tests are often unnecessary. A doctor will:
- Listen to the cough and breathing, and assess for stridor at rest
- Check breathing effort, oxygen levels, alertness and hydration
- Consider other causes of noisy breathing if the picture is unusual, for example a possible inhaled object or, rarely, a more serious airway infection
Imaging or blood tests are reserved for atypical or severe cases. The priority is assessing how hard the child is working to breathe.
Treatment options
Most croup is managed at home, and the aim is to keep the child calm, because crying and distress worsen the airway narrowing. Treatment includes:
- Comfort and calm: hold and soothe the child; an upright position is often easier for breathing.
- Fluids: offer regular drinks to keep the child hydrated.
- Fever relief: paracetamol can be used for fever or discomfort if a child is miserable, following dosing advice.
- Steroids: doctors commonly prescribe a single dose of an oral steroid (such as dexamethasone) to reduce airway swelling, even in milder cases.
- Hospital treatment: for moderate to severe croup, a child may be given nebulised adrenaline and observed, occasionally needing oxygen.
Steam and humidified air are no longer recommended as proven treatments. There are no special procedures or costs to plan for in routine croup.
When to see a doctor & which specialist
Call 995 or go to the nearest A&E immediately if a child with croup:
- Has stridor (a harsh sound on breathing in) while at rest and calm
- Is struggling to breathe, with the chest or neck pulling in
- Has blue or grey lips or face
- Is unusually drowsy, floppy or hard to wake
- Is drooling and cannot swallow, or is sitting still and very quiet to breathe
See a doctor the same day if the cough is severe, breathing is noisy when active, the child is not drinking, or you are worried. For ordinary daytime assessment and follow-up, start with a GP; you can find one through the best GP clinics in Singapore directory. Croup affects the upper airway and is different from bronchiolitis, which affects the smaller airways in the lungs of babies and tends to cause wheeze and fast breathing rather than a barking cough.
Related guides
- Best Paediatric Clinics in Singapore — our editorial shortlist
- paediatric clinics directory
- Sarcoma
- Bronchiolitis
- Stomach cancer
- Pancreatic cancer
- Peptic ulcer
Sources
- NHS – Croup
- Mayo Clinic – Croup
- HealthHub Singapore – Coughs and colds in children
- KK Women's and Children's Hospital
- MOH Singapore
Find a specialist
Prefer a named doctor? See our independent, sub-specialty-grouped directory of paediatricians in Singapore.
Part of our Children’s health guides · Browse all health topics