Bronchiolitis in Babies
The most common reason babies under 12 months end up in hospital in winter. What it looks like, what helps, and when to act fast.
- Last reviewed
- Sources cited
- 6 sources
- Author
- Dr Jubal John, FRACP
- Category
- medical guides
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Take-home
Bronchiolitis is a viral chest infection, usually RSV, affecting the small airways in babies under 12 months. Bronchiolitis is the largest single cause of hospital admission for infants in Australia and New Zealand, with RSV-related hospitalisation rates of around 8–17 per 1,000 infants in seasonal data, the majority under 6 months. The course is predictable: 3 days worse, 3 days the same, 3 days better. Most babies recover at home with small feeds often, nose saline + suction, and watching the work of breathing. No antibiotics, no inhalers, no steroids, no cough medicines: none of these help (RCH bronchiolitis CPG). The key skill for parents is recognising hard breathing early.
What bronchiolitis is
A virus (most often Respiratory Syncytial Virus: RSV) infects the smallest airways (bronchioles), causing inflammation and mucus. In babies under 12 months, these airways are already tiny, so even modest swelling causes:
- Snuffly nose
- Wheeze or crackles in the chest
- Cough
- Faster breathing, feeding difficulty from nose block
- Mild fever
Older children and adults get the same virus as a cold, bronchiolitis is essentially “a cold, but the baby’s plumbing can’t cope with it”.
The timeline
- Day 1–2: like a cold: snuffles, mild cough, maybe mild fever
- Day 3–5: the peak: worse cough, wheezy breathing, feeding harder, more tired
- Day 5–7: plateau, then gradual improvement
- Day 10–14: cough may linger but energy, feeds, and breathing are normal
The worst day is usually day 3–4. If your baby has been getting gradually worse for 3 days and today is day 3, they’re probably at or near the peak.
Signs of hard breathing (work of breathing)
This is the one thing worth knowing well. Any of these means review today:
Any one of these, especially if your baby is also feeding poorly or grunting with each breath, is a reason to seek review today.
Any one of these signs, especially alongside poor feeding, pale/sweaty/exhausted appearance, or a baby who won’t settle, warrants same-day review.
Breathing rate
A useful sanity check:
- < 6 months: breathing rate over 60/min at rest is high
- 6–12 months: over 50/min at rest is high
Count over a full minute while baby is asleep or calm (not crying). An upward trend over hours is more worrying than a single high count after a cry.
What helps at home
The kit for a bronchiolitis week
- Small feeds often: breast or bottle. Half the usual volume, twice as often. A blocked nose plus a large feed = failure.
- Saline nose drops before feeds: a few drops in each nostril, wait a minute
- Gentle nose suction (bulb syringe or nasal aspirator) before feeds
- Upright position for feeds and some awake time
- Paracetamol (age- and weight-appropriate dose) for fever over 38.5°C. Ibuprofen is not used under 3 months of age, and is generally avoided under 6 months without medical advice, paracetamol is the first choice in young infants.
- Offer extra fluid: don’t push; small frequent volumes
- Smoke-free home: cigarette smoke makes bronchiolitis significantly worse
- Rest: both of you. Nothing productive happens with a sick baby except feeds, sleeps, and watching.
Tracking wet nappies
Wet nappy count is a useful at-home guide to whether your baby is staying hydrated (weight is the most objective measure, but you can’t track that hour to hour at home). 4–6+ heavy wet nappies in 24 hours suggests they’re well hydrated. If it drops below 3–4 in 24 hours, seek medical review.
What doesn’t help (and why)
Treatments that sound right but don't work in bronchiolitis
- Antibiotics: bronchiolitis is viral. Antibiotics do nothing. They’re only used if a bacterial secondary infection is suspected (rare).
- Salbutamol / Ventolin inhalers: large RCTs + the Australian PREDICT guideline show no benefit in bronchiolitis under 12 months. It’s a different mechanism from asthma.
- Steroids (prednisolone): no benefit. Not recommended.
- Nebulised adrenaline: no proven benefit for outpatient or home use.
- Hypertonic saline nebulisers: used to be recommended; current evidence shows marginal or no benefit.
- Cough medicines / decongestants: not safe under 6 years, not effective.
- Chest physiotherapy: no benefit, can distress baby.
- Honey: sometimes used for older-child cough; never under 12 months (botulism risk).
Why the guidelines dropped these: most were abandoned between 2015–2020 as RCTs failed to show benefit. The RCH and PREDICT guidelines are explicit, supportive care only.
What about high-flow oxygen, CPAP, or hospital admission?
Those interventions matter when a baby can’t maintain their oxygen, hydration, or effort of breathing. That’s a hospital decision made on the day, not a home choice.
When to seek urgent medical attention
Green — usually fine
Green: manage at home
- Feeding at least half the usual amount
- Wet nappies normal for their feeds
- Breathing easy or only mildly snuffly, no drawn-in ribs
- Settles between coughing bouts, sleeps OK
Amber — be alert
Amber: seek review today (GP or us)
- Feeding less than half normal
- Breathing looks harder than this morning (not just a brief cough)
- Mildly drawn-in ribs, nostril flare, faster breathing
- Fewer wet nappies than usual
- Baby older than 2 months but feeding is a clear struggle
- You just feel they’re getting worse and not better
Red — act now
Red: Emergency Department / 000
- Grunting with each breath out
- Severe indrawing of ribs and stomach
- Pauses in breathing (apnoea, 20 seconds or more, or any pause with colour change or floppiness) or going blue around the lips / fingers
- Floppy, very sleepy, unresponsive
- Won’t feed at all, signs of dehydration (sunken fontanelle, no wet nappy for 8 hours, lethargy)
- Any baby under 2 months with significant breathing concerns
- Premature baby under 3 months corrected age with bronchiolitis symptoms
Higher-risk babies
The following groups are more likely to get severely unwell with bronchiolitis and generally need a lower threshold for review:
- Under 3 months (especially under 6 weeks)
- Premature babies
- Chronic lung disease of prematurity
- Congenital heart disease
- Underlying immune, neuromuscular, or respiratory conditions
- Baby in a smoking household
If your baby falls into one of these groups, any respiratory illness deserves earlier assessment, not later.
Preventing bronchiolitis
RSV protection: maternal vaccine and nirsevimab
Australia now runs a two-layer RSV protection program:
- Maternal RSV vaccine (Abrysvo): a single dose in pregnancy from 28 weeks, free under the National Immunisation Program. Antibodies cross the placenta and protect the baby through their most vulnerable months. If you’re pregnant, this is the default pathway, ask your obstetrician or GP.
- Nirsevimab (Beyfortus), a single long-acting monoclonal-antibody injection for the baby, funded during RSV season for infants whose mothers didn’t have the maternal vaccine (or had it less than 2 weeks before birth), and for higher-risk infants, including some preterm babies, who can also be covered in their second season.
The evidence behind this is strong: in the WA 2024 nirsevimab program, RSV-associated hospitalisations of infants under 1 year were about 57% lower than expected, with effectiveness around 86–88% (Bloomfield et al, MJA 2025).
Eligibility details shift season to season, if your baby arrived without maternal-vaccine protection, ask us, your GP or MCH nurse what applies this season.
Other prevention
- Hand-washing before handling baby, the single most effective intervention
- Avoid sick contacts in the first 3 months where possible
- Smoke-free home
- Breastfeeding: reduces severity of respiratory infections in infancy
- Vaccinations on schedule (including COVID, flu for eligible ages, pertussis for mum in pregnancy)
Common questions
“My baby’s been wheezing: is this asthma?”
Bronchiolitis under 12 months is not asthma. Some infants who have had bronchiolitis go on to have viral-induced wheeze in toddlerhood, but it’s not a guarantee, and the treatment of true asthma (much later) is different.
“How long will the cough last?”
The cough is the last thing to go. Up to 4 weeks of lingering cough after bronchiolitis is normal, as long as the baby is otherwise well, feeding, and breathing comfortably.
“Should I put my baby on antibiotics just in case?”
No. Unnecessary antibiotics in the first year of life are linked to higher rates of asthma, eczema, and gut disturbance later. Use them when they’re needed; not when they’re not.
“Is bronchiolitis contagious?”
Yes. RSV and other causes are highly contagious. Keep baby away from other young infants during the illness, and wash hands thoroughly.
“Can we go home with oxygen?”
Rarely, for specific high-risk babies with ongoing monitoring. Home oxygen is a specialist decision, not a convenience.
Related reading
Baby breathing harder than this morning?
With bronchiolitis a same-day review matters. If in doubt seek a medical review, or go to the Emergency Department for severe signs.