Bronchiolitis in Babies: Symptoms and When to Worry
In short: Bronchiolitis is a common viral chest infection in babies under 2, most often caused by RSV. It starts like a cold, then brings a cough, fast or noisy breathing and poorer feeding, usually at its worst on days 3 to 5. Most babies recover at home within 2 to 3 weeks with fluids and close watching. Medicines such as antibiotics, inhalers and steroids do not help, but some babies need hospital care for oxygen or feeding support.
Key takeaways
Bronchiolitis affects children under 2, with the highest numbers between 3 and 6 months of age.
Respiratory syncytial virus (RSV) is the most common cause, and in Malaysia RSV circulates all year round rather than in one short season.
Symptoms usually peak between days 3 and 5, and the cough settles within 3 weeks in about 90 percent of babies.
Antibiotics, salbutamol inhalers, nebulised adrenaline and steroids are not recommended for typical bronchiolitis because they do not change its course.
Pauses in breathing, grunting, blue or grey lips, or feeding at half the usual amount or less are reasons to see a doctor urgently.
What is bronchiolitis in babies?
Bronchiolitis is a viral infection of the smallest airways in the lungs, the bronchioles, which become swollen and clogged with mucus, making breathing harder work for a small baby.
A baby’s airways are tiny to begin with, so even a little swelling and mucus can narrow them noticeably. This is why the same virus that gives an older sibling or parent a simple cold can make a 3 month old baby breathless and tired.
What causes it?
RSV causes most cases. Other viruses, including rhinovirus, human metapneumovirus, parainfluenza and influenza, can cause the same illness. Almost every child has been infected with RSV by the age of 2, and it is possible to have bronchiolitis more than once.
Is it the same as pneumonia or asthma?
No. Pneumonia is an infection of the air sacs deeper in the lung and is more often bacterial. Asthma is a long-term tendency for the airways to tighten, and it is not usually diagnosed in babies. Bronchiolitis can cause wheezing, which is why it is sometimes confused with asthma, but in most babies it is a one-off viral illness.
Is there an RSV season in Malaysia?
In temperate countries RSV comes in winter. In tropical Malaysia it circulates throughout the year, with periodic rises rather than a predictable short season. Paediatricians in Malaysia describe RSV as a major cause of hospital admission in infants here, so it is worth knowing the signs at any time of year.
What are the symptoms of bronchiolitis, day by day?
Bronchiolitis starts as a cold for 1 to 3 days, then the cough and breathing worsen, peaking around days 3 to 5, before slowly improving over the following one to three weeks.
Days 1 to 2: the cold stage
Sneezing, a runny or blocked nose and sometimes a mild fever. Most babies with bronchiolitis do not have a very high temperature; NICE notes fever in around 30 percent, usually below 39°C.
Days 3 to 5: the chest stage
A persistent, sometimes rattly cough.
Breathing faster than usual.
Wheezing (a whistling sound on breathing out) or crackly breathing.
The skin pulling in between or under the ribs, or at the base of the neck, with each breath.
Shorter feeds, because a baby who is breathing hard cannot suck and breathe at the same time.
Fussiness and broken sleep.
After day 5: recovery
Breathing usually eases first, then feeding returns to normal. The cough is the last thing to go and can linger for up to 3 to 4 weeks. A lingering cough in a baby who is feeding and breathing comfortably is part of normal recovery. If it goes on much longer, our guide on a child’s cough that won’t go away may help.
Which babies are more likely to get seriously ill?
Babies under 3 months, babies born prematurely, and children with heart, lung, nerve and muscle or immune conditions are more likely to need hospital care with bronchiolitis.
Higher-risk groups
Babies younger than 3 months, and especially those under 6 weeks.
Babies born before 37 weeks, particularly before 32 weeks.
Children with chronic lung disease, including those who needed long-term oxygen after a premature birth.
Children with significant congenital heart disease.
Children with neuromuscular conditions or a weakened immune system.
Things that add to the risk
Exposure to cigarette or vape smoke, being in a crowded home or childcare setting with older children who bring viruses home, and not being breastfed are all linked with more severe illness. If your baby is in one of the higher-risk groups, it is reasonable to see a doctor early in the illness rather than waiting.
How is bronchiolitis treated?
There is no medicine that cures bronchiolitis; treatment means supporting breathing and feeding until the body clears the virus, at home for most babies and in hospital for some.
Why won’t the doctor give antibiotics or an inhaler?
Parents are often surprised to leave the clinic without a prescription. The UK NICE guideline, based on many studies, advises against antibiotics, salbutamol, ipratropium, montelukast, nebulised adrenaline, hypertonic saline and steroids for bronchiolitis, because they do not shorten the illness or prevent admission. Antibiotics are used only if a doctor suspects a separate bacterial infection.
What happens in hospital?
Babies are admitted for one of two main reasons: low oxygen levels or not feeding enough. Hospital care may include oxygen through small nasal prongs, gentle suction of the nose, and milk given through a thin tube into the stomach or fluids through a drip. A small number need high-flow oxygen or breathing support in a high dependency or intensive care unit. Most babies admitted with bronchiolitis go home within a few days.
Can bronchiolitis be prevented?
Handwashing, keeping young babies away from people with colds, and a smoke-free home all reduce the risk. A long-acting RSV antibody injection for infants (nirsevimab) has been approved in Malaysia but is not part of the National Immunisation Programme. If your baby was premature or has a heart or lung condition, ask your paediatrician whether RSV prevention is suitable.
When to see a doctor, and when not to worry
Watch your baby’s breathing effort and feeding more than the cough: a baby who breathes comfortably between coughs and takes most of their usual feeds can usually stay at home.
Usually fine
A runny nose and cough, with breathing that is a little faster but not laboured.
Occasional wheeze or rattly sounds in a baby who is otherwise alert and feeding.
Feeds that are shorter but more frequent, adding up to most of the usual amount.
A cough that hangs on for 2 to 3 weeks while your baby is otherwise improving.
Book an appointment soon
Your baby is under 3 months old, was premature, or has a heart, lung or immune condition, and has cold symptoms with a cough.
Symptoms are getting worse after day 5 instead of better.
Fever lasts more than 3 days or comes back after settling.
The cough is still present after 4 weeks.
Your baby is unusually tired or irritable, or you are worried.
See a doctor the same day
Your baby is taking about half or less of their usual feeds.
No wet nappy for 12 hours, a dry mouth or no tears.
Breathing that looks like hard work: ribs sucking in, nostrils flaring, head bobbing or grunting with each breath.
Very fast breathing at rest, for example more than 60 breaths a minute when counted for a full minute while your baby is calm.
A temperature of 38°C or higher in a baby under 3 months.
Pauses in breathing, blue or grey lips or tongue, or a baby who is floppy and hard to wake. Call 999 or go to the nearest emergency department straight away.
What you can do at home
Home care is about small, frequent feeds, a clear nose, an upright position when awake and regular checks, including at night.
Babies under 6 months
Offer smaller breastfeeds or bottles more often. Keep a rough note of feeds and wet nappies so you can tell your doctor.
Use saline nose drops before feeds to loosen mucus. A gentle nasal aspirator can help if the nose is very blocked, but do not suction repeatedly.
Hold your baby upright for feeds and for a while afterwards.
Always put your baby to sleep on their back on a firm, flat surface, even when they have a cold. Do not prop them up on pillows in the cot.
If your baby is distressed by a fever and is over 2 months old, paracetamol suitable for their age and weight can be used. Check the dose with your pharmacist or doctor.
Babies and toddlers from 6 months to 2 years
Offer milk and water little and often. Solid food matters less for a few days.
Saline drops or spray can still help a blocked nose.
Keep them away from smoke and, during haze days, keep windows closed. Our article on haze and children has practical tips.
Keep them home from taska while they are unwell and breathing fast, both for their comfort and to protect younger babies there.
What not to do
Do not give cough and cold medicines, decongestant nose drops or antihistamines. They do not help babies and can cause side effects.
Do not ask for antibiotics or inhalers “just in case”.
Do not use steam inhalation or hot water bowls near a baby, because of the risk of scalds.
Do not rub strong menthol or camphor balms near a baby’s nose or mouth.
Do not smoke or vape in the house or car.
Do not give aspirin to children.
From Dr Nisa’s clinic [DR NISA TO CONFIRM OR REWRITE]: Parents often bring a baby with bronchiolitis expecting medicine, and leave with a plan instead. I understand why that feels unsatisfying. What I find most useful is teaching parents what to watch: how hard the chest is working, how much milk is going in, how many wet nappies come out. Those three things tell us far more than the sound of the cough. A noisy chest in a baby who is feeding well is usually much less worrying than a quiet baby who has stopped feeding.
Worried about bronchiolitis in your baby?
I am Dr Nisa Khalil, a consultant paediatrician with more than 18 years of experience, seeing babies and children at ParkCity Medical Centre in Desa ParkCity, Kuala Lumpur. If your baby has a cough and fast breathing and you would like them checked, you can book an appointment or ask a question through an online eConsult. If your baby has any of the same-day warning signs above, please go to your nearest emergency department.
You may also find these helpful:
Frequently asked questions
How long does bronchiolitis last in babies?
Bronchiolitis usually lasts 2 to 3 weeks in total. The first 1 to 3 days look like a cold, symptoms are usually worst between days 3 and 5, and breathing and feeding then improve. The cough is the last symptom to settle and goes within 3 weeks in about 90 percent of babies. If your baby is getting worse after day 5, or still coughing after 4 weeks, see a doctor.
Is bronchiolitis contagious?
Yes. The viruses that cause bronchiolitis, especially RSV, spread through coughs, sneezes and contaminated hands and surfaces. Older children and adults usually only get a cold, then pass it to babies. Wash your hands before handling your baby, keep them away from people with colds where possible, and keep a sick toddler home from taska until they are well.
Can I treat bronchiolitis at home?
Most babies with bronchiolitis can be cared for at home. Offer small, frequent feeds, use saline drops to clear the nose, keep your baby upright when awake and check on them regularly, including overnight. Home care is not suitable if your baby is feeding half their usual amount or less, has no wet nappy for 12 hours, is working hard to breathe, or has pauses in breathing.
Will bronchiolitis lead to asthma?
Not in most children. Many babies with bronchiolitis have no further breathing problems. Some do have repeated wheezy episodes with colds for a year or two, particularly after severe RSV bronchiolitis, and a smaller number go on to have asthma. Family history of asthma or eczema and smoke exposure increase this chance. Your doctor can review your child if wheezing keeps returning.
How do I count my baby’s breathing rate?
Wait until your baby is calm or asleep, uncover their tummy and count each rise of the chest or belly for a full 60 seconds. Babies normally breathe much faster than adults. A count above 60 at rest, or breathing that looks like hard work, needs a doctor the same day. Taking a short video can help your doctor.
Medically reviewed by Dr Nisa Khalil on [DATE]. This article is general information and does not replace a consultation with your own doctor.
References
NICE. Bronchiolitis in children: diagnosis and management (NG9), updated 2021. https://www.nice.org.uk/guidance/ng9
NHS. Bronchiolitis. https://www.nhs.uk/conditions/bronchiolitis/
American Academy of Pediatrics, HealthyChildren.org. Bronchiolitis. https://www.healthychildren.org/English/health-issues/conditions/chest-lungs/Pages/Bronchiolitis.aspx
Nordin MM, Ismail Z. Protecting Malaysia’s children from an invisible threat. CodeBlue, 3 June 2026. https://codeblue.galencentre.org/2026/06/protecting-malaysias-children-from-an-invisible-threat-dr-musa-mohd-nordin-dr-zulkifli-ismail/
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