Red Flags
- Apnoea, severe respiratory distress (RR >70/min, intercostal and subcostal recession, head bobbing, grunting), or SpO2 <90% on room air — emergency admission and respiratory support[1]
- Poor feeding (<50% usual), dehydration signs, lethargy, or central cyanosis — admit; IV/NG fluids; high-flow oxygen[1]
- Age <3 months, ex-prematurity (<32 weeks), congenital heart or chronic lung disease, immunodeficiency — lower threshold for admission and observation[1]
- Worsening despite supportive care after 24 h or persistent SpO2 <92% on supplemental oxygen — escalate to high-flow nasal oxygen or CPAP; PICU consult[1]
First-line treatment
Interventions
- Supportive care as the foundation[1]Adequate oxygenation (target SpO2 ≥90–92%), nasal saline drops + bulb suction, small frequent feeds (NG if poor oral intake), upright positioning, watchful monitoring
- Oxygen delivery and respiratory support[1]Low-flow nasal cannula for SpO2 <90%; high-flow nasal cannula (1–2 L/kg/min) for moderate-severe distress; CPAP or HFNC pre-PICU; intubation only if respiratory failure
- Hydration and feeding support[1]NG feeds preferred over IV fluids when possible; isotonic IV fluids if NG not tolerated; avoid hypotonic fluids (SIADH risk)
- Avoid ineffective therapies[1]Routine bronchodilators NOT recommended (no benefit); routine systemic or inhaled steroids NOT recommended; routine antibiotics NOT recommended; nebulised hypertonic saline only for inpatients with anticipated long stay
- RSV prevention — passive immunisation[1]Nirsevimab single dose at start of RSV season for all infants entering first RSV season and at-risk infants in second season; palivizumab where nirsevimab unavailable, monthly during season for high-risk infants
- Maternal RSVpreF vaccination[1]Maternal RSV vaccine at 32+0 to 36+6 weeks gestation provides passive antibody protection to newborn against RSV bronchiolitis
First-line drug therapy
| Drug | Class | Adult | Paediatric | Notes |
|---|---|---|---|---|
| Nirsevimab[1] | Long-acting anti-RSV F protein monoclonal antibody | Not applicable — paediatric prophylaxis | Infants <5 kg: 50 mg IM single dose; ≥5 kg: 100 mg IM single dose at start of RSV season; second-season at-risk: 200 mg IM | Replaces palivizumab in most settings; provides 5-month protection from one dose; reduces RSV bronchiolitis hospitalisation by ~80% |
| Palivizumab[1] | Anti-RSV F protein monoclonal antibody | Not applicable — paediatric prophylaxis | 15 mg/kg IM monthly throughout RSV season (max 5 doses) | Reserved for ex-prematurity, congenital heart disease, chronic lung disease where nirsevimab not available; replaced by nirsevimab in most national programmes from 2024 |
| Nebulised hypertonic 3% saline (selected inpatients)[1] | Mucolytic / hyperosmolar | Not applicable — paediatric prophylaxis | 4 mL nebulised every 2–4 h for first 24 h then less frequent | Inpatients with anticipated stay >24 h; not for outpatient use; pre-treat with bronchodilator if reactive airways concern |
Nirsevimab[1]
Long-acting anti-RSV F protein monoclonal antibody
- Adult
- Not applicable — paediatric prophylaxis
- Paediatric
- Infants <5 kg: 50 mg IM single dose; ≥5 kg: 100 mg IM single dose at start of RSV season; second-season at-risk: 200 mg IM
Replaces palivizumab in most settings; provides 5-month protection from one dose; reduces RSV bronchiolitis hospitalisation by ~80%
Palivizumab[1]
Anti-RSV F protein monoclonal antibody
- Adult
- Not applicable — paediatric prophylaxis
- Paediatric
- 15 mg/kg IM monthly throughout RSV season (max 5 doses)
Reserved for ex-prematurity, congenital heart disease, chronic lung disease where nirsevimab not available; replaced by nirsevimab in most national programmes from 2024
Nebulised hypertonic 3% saline (selected inpatients)[1]
Mucolytic / hyperosmolar
- Adult
- Not applicable — paediatric prophylaxis
- Paediatric
- 4 mL nebulised every 2–4 h for first 24 h then less frequent
Inpatients with anticipated stay >24 h; not for outpatient use; pre-treat with bronchodilator if reactive airways concern
Safety-net
- Symptoms typically peak at days 3–5 and resolve over 1–2 weeks; cough may persist 3–4 weeks[1]
- Return same-day if breathing becomes faster or harder, baby cannot feed, becomes drowsy/floppy, lips look blue, or fewer than half normal wet nappies[1]
- Hand hygiene and avoiding tobacco smoke exposure reduce respiratory infections; older siblings often bring viruses home[1]
Referral criteria
- Apnoea, severe distress, hypoxia, dehydration, or age <3 months with moderate-severe diseaseEmergency department / paediatric admission[1]
- Worsening despite high-flow nasal cannula or CPAPPaediatric intensive care[1]
- High-risk infants entering RSV season without prophylaxisCommunity paediatrics / immunisation clinic for nirsevimab or palivizumab[1]
- Recurrent or atypical bronchiolitis at age >18 months or >2 episodesPaediatric respiratory medicine — consider asthma, immunodeficiency, anatomical airway lesion[1]
Clinical summary
Diagnosis and supportive care for acute viral bronchiolitis in infants <2 years; nirsevimab and palivizumab prophylaxis pathways.