Bronchiolitis Management Update: What the Evidence Shows
Synthesising 12 studies — including Cochrane reviews, multicentre RCTs, and updated international guidelines — on why supportive care remains the cornerstone of bronchiolitis management, and where emerging evidence challenges or refines the “less is more” paradigm. Through 2025.
This is an original evidence synthesis. See References for source studies.
One-Minute Takeaway
One-Minute Takeaway
- Bronchiolitis management remains centred on supportive care — hydration, minimal handling, and oxygen for hypoxaemia — with strong and consistent evidence against routine use of bronchodilators, corticosteroids, and antibiotics from multiple international guidelines and Cochrane reviews.
- High-flow nasal cannula (HFNC) therapy is associated with reduced treatment escalation compared to standard oxygen (RR approximately 0.55 across trials), though most infants with mild-to-moderate disease manage well on low-flow oxygen alone.
- A Cochrane review of 34 trials (5,205 infants) found that nebulised hypertonic saline may modestly reduce hospital stay by approximately 10 hours in admitted infants, though evidence certainty is low to very low.
- Emerging phenotyping research suggests bronchiolitis may encompass distinct endotypes with differing pathobiology and treatment responsiveness — a finding that could eventually shift management away from a uniform “one-size-fits-all” supportive approach, but which remains preliminary.
Why Bronchiolitis Management Matters
Bronchiolitis is the single most common cause of hospital admission for respiratory illness in infants under one year of age worldwide. In the United States alone, bronchiolitis accounts for over 100,000 hospitalisations annually, with direct medical costs exceeding several hundred million dollars per year. RSV remains the predominant pathogen, responsible for approximately 60–80% of cases during the winter season.
Despite decades of research and clear guideline recommendations, substantial practice variation persists. Audit data from multiple countries show that non-evidence-based therapies — including nebulised bronchodilators, systemic corticosteroids, and unnecessary chest radiographs — continue to be used in a significant proportion of cases. A recent Italian multicentre study found that while adherence to evidence-based guidelines improved over two consecutive bronchiolitis seasons, use of non-recommended therapies such as nebulised beta-2 agonists and antibiotics remained notable.
The gap between what the evidence supports and what clinicians do at the bedside makes this topic particularly important. Each unnecessary intervention carries costs — financial, in terms of hospital resources and nursing time, but also in terms of potential harm and prolonged stays for infants who would otherwise recover with simple supportive measures.
What Evidence Was Reviewed
This synthesis draws on Cochrane systematic reviews, large multicentre randomised controlled trials, updated international clinical practice guidelines (AAP 2014, NICE 2021, Australasian 2025), umbrella reviews, and emerging phenotyping research. The evidence spans the full spectrum of bronchiolitis interventions — from pharmacological therapies shown to be ineffective to respiratory support strategies with varying levels of support.
| Study | Design | n | Population | Key Finding | Quality |
|---|---|---|---|---|---|
| Zhang et al. 2023 (Cochrane) | SR/MA | 5,205 | Infants <24 mo with bronchiolitis | Nebulised HS may reduce LOS by ~10 h; low-to-very-low certainty | Low |
| Franklin et al. 2018 (NEJM) | Multicentre RCT | 1,472 | Infants <12 mo with bronchiolitis + O₂ need | HFNC reduced treatment escalation vs standard O₂ therapy | High |
| Cochrane HFNC Review 2024 | SR/MA | 2,813 | Infants <24 mo | HFNC associated with reduced escalation, modest LOS reduction | Moderate |
| Ralston et al. (AAP) 2014 | Clinical guideline | NR | Children 1–23 mo | Recommends against routine bronchodilators, corticosteroids, antibiotics | High |
| NICE NG9 2021 | Clinical guideline | NR | Children <2 yr | Supportive care only; O₂ if SpO₂ persistently ≤92% | High |
| Borland et al. 2025 (Australasian) | Clinical guideline | NR | Infants with bronchiolitis (ED/ward/ICU) | 41 GRADE-based recommendations; expanded to include ICU, RSV prevention | High |
| Mellick et al. 2025 (Umbrella review) | Umbrella review of MAs | NR | Outpatient bronchiolitis | Some evidence supports therapeutic trials of albuterol, HS, epinephrine in outpatients | Moderate |
| Kirolos et al. 2020 | SR of guidelines | NR | Children with bronchiolitis | Widespread agreement on avoiding unnecessary tests; variation in pharmacotherapy | Moderate |
| Hartling et al. 2011 | SR/MA | 5,862 | Children <2 yr | No benefit for steroids or bronchodilators; no interaction between them | High |
| Aricò et al. 2025 | Multicentre retrospective | 623 | Infants <24 mo admitted with bronchiolitis | Reduced use of non-recommended therapies after guideline implementation | Low |
| Schuh et al. 2014 | RCT | NR | ED bronchiolitis | Clinician behaviour influenced by SpO₂ display; artificially higher readings reduced admissions | Moderate |
| Fernandes et al. (BIDS) 2015 | RCT | 615 | Infants with bronchiolitis | SpO₂ target 90% vs 94%: no difference in cough duration (~15 days); lower target may permit earlier discharge | High |
Key Findings on Bronchiolitis Management
The Case for Supportive Care Alone
The most consistent finding across the evidence base is the ineffectiveness of pharmacological interventions that were once routine. Hartling et al.’s comprehensive systematic review and meta-analysis of over 5,800 children found no meaningful benefit for either corticosteroids or bronchodilators, singly or in combination. The AAP guideline codified this evidence into strong recommendations against routine use of albuterol, epinephrine, systemic corticosteroids, chest physiotherapy, and antibiotics.
Kirolos et al.’s systematic comparison of international guidelines found widespread agreement on avoiding unnecessary diagnostic testing and pharmacological treatments. However, significant variation remained in specific pharmacological recommendations — particularly around whether nebulised epinephrine or hypertonic saline should be trialled. This variation likely reflects the tension between population-level evidence showing no benefit and individual clinician experience suggesting occasional responders.
Respiratory Support: From Low-Flow to High-Flow
The Franklin et al. multicentre RCT (1,472 infants, 17 hospitals) provided the strongest evidence to date on HFNC in bronchiolitis. Among infants requiring supplemental oxygen, those randomised to HFNC had significantly fewer treatment escalation events compared to standard oxygen therapy. Importantly, 61% of infants who initially failed standard therapy responded to rescue HFNC, suggesting that a “step-up” approach — starting with low-flow and escalating to HFNC only on failure — may be the most resource-efficient strategy.
The 2024 Cochrane review of 16 RCTs (2,813 infants) corroborated these findings, reporting that HFNC was associated with greater improvement in respiratory and heart rates, a modest reduction in hospital stay, and reduced treatment escalation, without increased adverse events. However, approximately 75% of infants with mild-to-moderate disease managed well on standard oxygen alone — highlighting that HFNC is not universally needed.
Oxygen Saturation Targets: How Low Can We Go?
The question of oxygen saturation thresholds has substantial implications for admission rates and length of stay. The BIDS trial directly compared SpO₂ targets of 90% versus 94% in hospitalised bronchiolitis infants and found no difference in the duration of cough (approximately 15 days in both groups). NICE recommends supplemental oxygen when saturation is persistently 92% or below, while the 2025 Australasian guideline sets the threshold at below 90% for otherwise healthy infants aged six weeks and older.
Schuh et al.’s revealing experiment demonstrated that clinician decision-making is heavily influenced by displayed SpO₂ values: when experimenters artificially raised the displayed saturation, significantly fewer infants were admitted. This finding underscores the importance of assessing the whole child — activity, feeding, respiratory effort — rather than fixating on a single number from the pulse oximeter.
The 2023 Cochrane review by Zhang et al. (34 trials, 5,205 infants) found that nebulised 3% hypertonic saline may reduce hospital stay by approximately 9.6 hours compared to normal saline in admitted infants, and may reduce the risk of hospitalisation by 13% in ED and outpatient settings. However, the certainty of evidence was low to very low across all outcomes, largely due to inconsistency, clinical heterogeneity, and risk of bias.
Notably, the effect size shrank substantially from the 2013 update (which reported a 1.2-day reduction) as larger, higher-quality trials were included. The largest and most precise individual trials showed smaller or non-significant effects, raising questions about whether pooled estimates overstate the true benefit. The 2025 Australasian guideline does not recommend routine use of nebulised hypertonic saline, citing low-certainty evidence.
Cost considerations may nonetheless favour its use in settings where even modest reductions in stay duration have meaningful resource implications, particularly in lower-resource health systems where the intervention’s low cost and minimal adverse event profile make it an attractive option.
Mellick et al.’s 2025 umbrella review took a provocative look at the outpatient evidence for medications the AAP guideline recommended against — albuterol, epinephrine, and hypertonic saline. Their analysis of 21 meta-analyses identified evidence, drawn predominantly from outpatient subanalyses, that some individual patients may demonstrate clinical responses to these agents in emergency department or outpatient settings.
The authors argue that the heterogeneity of patients under the umbrella term “bronchiolitis” means that blanket recommendations against any therapeutic trial may disadvantage a subset of responders. They call for adequately powered RCTs designed to identify which phenotypic subgroups, if any, benefit from specific interventions. This position aligns with emerging phenotyping research but remains contentious — current evidence does not yet support changing guideline recommendations.
An emerging body of research suggests that bronchiolitis is not a single homogeneous disease but an umbrella term encompassing distinct endotypes and phenotypes that differ in pathobiology, viral aetiology, immune response, and clinical trajectory. RSV-predominant bronchiolitis, for instance, appears to differ from rhinovirus-associated wheezing in terms of both acute pathophysiology and long-term risk of recurrent wheeze and asthma.
This phenotypic heterogeneity may explain why population-level trials of bronchodilators and corticosteroids have consistently shown null results: a meaningful treatment effect in one subgroup could be diluted by null or harmful effects in others. The Tucson Children’s Respiratory Study demonstrated that infants with RSV lower respiratory tract infections had a significantly elevated risk of subsequent wheeze — a finding replicated in the MARC-35 multicentre prospective cohort.
While this line of inquiry is compelling, it remains largely observational and hypothesis-generating. No randomised trials have yet demonstrated that phenotype-guided treatment improves outcomes in bronchiolitis. Until such evidence emerges, supportive care remains the evidence-based standard for all infants.
Aricò et al.’s 2025 multicentre Italian study of 623 infants demonstrated that structured quality improvement efforts can reduce the use of non-recommended therapies across bronchiolitis seasons. Compared to the 2021–2022 season, subsequent seasons showed reduced use of nebulised beta-2 agonists, systemic corticosteroids, and antibiotics. However, complete elimination of non-evidence-based practices proved elusive, and HFNC use patterns remained heterogeneous across centres.
These findings are consistent with broader implementation science literature suggesting that deimplementation — the withdrawal of established but ineffective practices — is often harder to achieve than implementation of new interventions. Clinician discomfort with “doing nothing,” parental expectations for active treatment, and institutional inertia all contribute to the persistence of non-recommended therapies.
Quality & Consistency of Evidence
What the Evidence Does Not Show
No adequately powered RCTs have tested whether phenotype-guided therapy — for example, bronchodilators for rhinovirus-positive infants with a family history of atopy versus pure supportive care for RSV-predominant disease — improves outcomes compared to the current uniform supportive care approach. This remains the most important unanswered question in bronchiolitis research.
The optimal timing for HFNC initiation is unclear. The Franklin trial used HFNC as first-line therapy, yet 75% of infants managed on standard oxygen did not require escalation. Whether early universal HFNC or a rescue-only strategy produces better outcomes and greater cost-effectiveness has not been definitively established in a head-to-head comparison.
Evidence on bronchiolitis management in the primary care and community setting is notably sparse. Most trials have been conducted in emergency departments or inpatient wards. Similarly, robust data on the impact of RSV immunoprophylaxis with newer agents such as nirsevimab and clesrovimab on the overall burden of bronchiolitis hospitalisations are still emerging as these agents enter widespread use.
Practical Implications
Based on the current evidence, the following considerations may inform clinical decision-making for infants presenting with bronchiolitis. These reflect the synthesised evidence base rather than prescriptive directives.
Concordant data from multiple systematic reviews and all major international guidelines indicate that routine bronchodilators, corticosteroids, antibiotics, and chest physiotherapy do not improve outcomes. The available evidence supports focusing on hydration, gentle nasal suctioning when clinically needed, and supplemental oxygen only for documented hypoxaemia.
The Franklin trial and subsequent Cochrane review support HFNC for infants who fail standard oxygen therapy. A “start low, escalate if needed” approach appears both clinically effective and cost-efficient, with approximately 60% of initial standard-oxygen failures responding to rescue HFNC.
The BIDS trial and current guideline recommendations support accepting SpO₂ thresholds of 90–92% in otherwise healthy infants over six weeks of age. Assessing the child’s overall clinical status — feeding ability, alertness, work of breathing — carries more weight than a specific SpO₂ number.
Evidence suggests that continuous SpO₂ monitoring in clinically improving infants leads to longer hospitalisations without intrinsic patient benefit, as staff and parents respond to transient desaturations that are clinically insignificant. Intermittent monitoring in stable, improving infants is supported by current evidence.
Evidence Grade & Bottom Line
Overall Evidence Grade: Strong (for core supportive management) / Moderate (for respiratory support strategies)
The evidence against routine pharmacotherapy in bronchiolitis is robust, consistent, and unlikely to change. Evidence supporting HFNC as rescue therapy and lower SpO₂ targets is moderate and broadly concordant. Evidence for hypertonic saline and phenotype-guided therapy remains limited or insufficient.
- Supportive care — hydration, minimal handling, and oxygen for hypoxaemia — is the only evidence-based treatment for bronchiolitis, supported by strong and concordant international evidence.
- HFNC reduces treatment escalation and is most effectively deployed as rescue therapy for infants who fail standard oxygen.
- Accepting lower SpO₂ targets (90–92%) in otherwise healthy older infants may safely reduce admissions and length of stay.
- Nebulised hypertonic saline may offer a modest reduction in hospital stay, but evidence certainty is low and the largest individual trials show smaller effects than pooled estimates suggest.
- Phenotype-guided management is a promising research direction but currently lacks randomised evidence to support clinical application.
Article Information
For Educational Purposes Only. This is an original evidence synthesis informed by the studies listed below. It does not replace clinical judgement. Drug dosages should be verified against current prescribing information.
References
- Zhang L, Mendoza-Sassi RA, Wainwright CE, Aregbesola A, Klassen TP. Nebulised hypertonic saline solution for acute bronchiolitis in infants. Cochrane Database Syst Rev. 2023;4(4):CD006458. DOI: 10.1002/14651858.CD006458.pub5
- Franklin D, Babl FE, Schlapbach LJ, et al. A randomized trial of high-flow oxygen therapy in infants with bronchiolitis. N Engl J Med. 2018;378(12):1121–1131. DOI: 10.1056/NEJMoa1714855
- Ralston SL, Lieberthal AS, Meissner HC, et al. Clinical practice guideline: the diagnosis, management, and prevention of bronchiolitis. Pediatrics. 2014;134(5):e1474–e1502. DOI: 10.1542/peds.2014-2742
- National Institute for Health and Care Excellence. Bronchiolitis in children: diagnosis and management (NG9). NICE; 2021. Available at: https://www.nice.org.uk/guidance/ng9
- Borland ML, Babl FE, Dalziel SR, et al. Australasian Bronchiolitis Guideline: 2025 Update. J Paediatr Child Health. 2025. DOI: 10.1111/jpc.70144
- Hartling L, Fernandes RM, Bialy L, et al. Steroids and bronchodilators for acute bronchiolitis in the first two years of life: systematic review and meta-analysis. BMJ. 2011;342:d1714. DOI: 10.1136/bmj.d1714
- Mellick L, Walsh P, Clanton C, Kalra S, McKinney S. Outpatient medications deimplemented by the AAP bronchiolitis guidelines: an umbrella review of meta-analyses. Pediatr Pulmonol. 2025;60(1):e27391. DOI: 10.1002/ppul.27391
- Kirolos A, Manti S, Blacow R, et al. A systematic review of clinical practice guidelines for the diagnosis and management of bronchiolitis. J Infect Dis. 2020;222(Suppl 7):S672–S679. DOI: 10.1093/infdis/jiz240
- Aricò MO, Accomando F, Trotta D, et al. Bronchiolitis: a real-life report of increasing compliance to treatment guidelines. Children (Basel). 2025;12(5):571. DOI: 10.3390/children12050571
- Armarego M, Forde H, et al. High-flow nasal cannula therapy for infants with bronchiolitis. Cochrane Database Syst Rev. 2024;3:CD009609. DOI: 10.1002/14651858.CD009609.pub2
- Cunningham S, Rodriguez A, Adams T, et al. Oxygen saturation targets in infants with bronchiolitis (BIDS): a double-blind, randomised, equivalence trial. Lancet. 2015;386(9998):1041–1048. DOI: 10.1016/S0140-6736(15)00163-4
- Meissner HC. Viral bronchiolitis in children. N Engl J Med. 2016;374(1):62–72. DOI: 10.1056/NEJMra1413456