Acute asthma

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  • See also

    Asthma in adolescents (12 years and over)
    Asthma in primary school aged children (6-11 years)
    Preschool asthma (1-5 years)

    Key points

    1. If unsure if a child has anaphylaxis or asthma, treat for anaphylaxis. Treatment of both is time critical
    2. Metered dose inhalers (MDI) are preferable to nebulisers given their rapid delivery, comparable efficacy and fewer side effects
    3. Short acting beta agonist (SABA) therapy is crucial to the management of asthma
    4. Give steroids early in moderate, severe and life-threatening asthma
    5. Adolescents on combination reliever/preventer therapy (ie budesonide/formoterol dry powder inhalation) should be managed with salbutamol for an acute exacerbation requiring treatment in hospital


    • Asthma is a chronic inflammatory disease of the airways characterised by reversible airways obstruction and bronchospasm
    • Exacerbations in children are often precipitated by a respiratory viral infection
    • Coexisting atopy is common
    • Children <12 months of age presenting with wheeze are likely to have bronchiolitis that does not respond to bronchodilator treatment
    • MDIs have a large carbon footprint so where possible the use of dry powder inhalers (DPI) is preferable



    • Sudden onset of symptoms after insect sting or ingestion of food/medication may suggest anaphylaxis and not asthma alone
    • Treatments used during this illness (reliever dose, frequency and ongoing effectiveness)
    • Preventer treatment (technique and adherence)
    • Triggers (including upper respiratory tract infection, passive smoking, exercise, cold air, aero-allergen exposure)
    • Pattern and course of previous episodes:
      • 2 or more presentations to hospital that require treatment for asthma
      • IV treatment
      • ICU admission or intubation
      • Using SABA more than twice/week or >3 MDI canisters per year
    • Presence of interval symptoms (eg nocturnal cough, exercise induced wheeze, morning cough), school attendance, participation in physical activity
    • Comorbidities such as anaphylaxis and allergic rhinitis


    • The best measures of severity are general appearance, mental state, activity and work of breathing (respiratory rate, accessory muscle use, retraction)
    • Assess air entry
    • Wheeze intensity, pulsus paradoxus and peak expiratory flow rate are not reliable. A child that looks unwell with a silent chest (no wheeze) may herald imminent respiratory collapse
    • Initial SpO2, heart rate and ability to talk are helpful but less reliable additional features 
    • Tachycardia can be a sign of severity but is also a side effect of beta agonists such as salbutamol
    • Asymmetry on auscultation is often found due to mucus plugging, but persistent asymmetry may indicate other causes such as inhaled foreign body or pneumothorax

    Red flags for alternative diagnoses: 

    • productive cough
    • isolated cough
    • paraesthesia
    • chest pain
    • clubbing



    • Investigations are generally not needed. Chest x-ray is not required
    • Bloods are rarely performed
      • Blood gases are distressing and can cause a child with respiratory compromise to deteriorate further. They are not usually required and the child's clinical state is more important in guiding treatment
      • Measurement of serum potassium may be indicated when there has been prolonged or frequent salbutamol use (see Other management considerations listed below)


    • Standard salbutamol metered dose inhaler (MDI) has 100 microg/puff and standard ipratropium bromide MDI has 21 microg/puff
    • See management flow charts below, based on severity

    Classification of asthma severity





    Life threatening


    • Mild increased work of breathing (WOB)
    • Normal respiratory rate
    • Alert and active
    • Moderate increased work of breathing
    • Increased respiratory rate
    • Active and alert
    • Markedly increased work of breathing
    • Increased respiratory rate
    • Agitated
    • Pale
    • Other signs of anaphylaxis
    • Maximal work of breathing
    • Increased respiratory rate
    • Confused/ drowsy
    • Not moving
    • Cyanosed
    • Other signs of anaphylaxis

     Management of mild asthma

    Management of mild asthma flowchart

    Management of moderate asthma

    Management of moderate asthma flowchart


    Management of severe asthma

    Management of severe asthma flowchart

    Management of life-threatening asthma flowchart

    Management of life-threatening asthma flowchart

    IV magnesium sulfate 50% dosing

    • Product specifications: 1 mL = 2 mmol = 500 mg
    • Check doses carefully
      • 0.2 mmol/kg = 50 mg/kg = 0.1 mL/kg (undiluted magnesium sulfate)
      • max 8 mmol
    • Dilute as per local guidelines and check concentrations carefully before administration

    Other management considerations

    • Dexamethasone causes less vomiting and has a longer half life
    • In life-threatening acute asthma, IM adrenaline can provide bronchodilation in children with poor respiratory effort to optimise delivery of inhaled therapy
    • If no response to salbutamol, seek senior advice and consider alternative diagnosis (eg anatomical airway abnormalities, cystic fibrosis, bronchomalacia)
    • Mask and spacer can be applied over nasal prong oxygen to deliver inhaled bronchodilator
    • Salbutamol toxicity clinically presents with tachycardia, tachypnoea and fine tremors. Biochemical assessment is often helpful in this setting for confirmation (hypokalaemia, hyperlactataemia and metabolic acidosis) before pausing SABA therapy. Hypokalaemia rapidly corrects when salbutamol dosing reduces

    Consider consultation with local paediatric team when

    • Moderate, severe or life-threatening asthma
    • Poor response to inhaled salbutamol
    • Oxygen requirement

    Consider transfer when

    • Severe or critical asthma requiring intravenous treatment or respiratory support
    • Children with escalating oxygen requirement
    • Children poorly salbutamol responsive or unable to wean salbutamol requirement
    • Children requiring care above the level of comfort of the local hospital

    For emergency advice and paediatric or neonatal ICU transfers, see Retrieval Services

    Consider discharge when

    • In consultation with a senior clinician, some children can be discharged at one hour if they have:
      • resolution of all signs of severity
      • normal activity
      • adequate parent skill and familiarity with asthma
      • proximity to emergency care
    • All other children should be able to tolerate three hours without requiring salbutamol MDI
    • Adequate oxygenation: mild hypoxia (SpO2 90-94%) should not preclude discharge if child is clinically well and has responded well to treatment
    • Adequate oral intake

    Discharge instructions

    • Education: assess knowledge and understanding and address gaps on
      • symptom recognition and management
      • when to seek medical attention
      • emergency management
      • role of reliever and preventer therapy
      • inhaler technique
    • Follow-up organised with long term care provider (GP or specialist)
    • Updated Asthma Action Plan with verbal discussion of plan provided, should include information on management of the current episode. Document provision of the Asthma Action Plan and the associated discussion in your medical record. Action Plan Library
    • Consider community asthma program (or Asthma Australia phone follow-up) for reinforcement of education
    • Consider associated atopic condition education and management
      • Anaphylaxis morbidity and mortality is increased if asthma is not well controlled
      • Allergic rhinitis

    Parent information

    RCH Kids Health Info Fact Sheet: Asthma
    RCH Kids Health Info: Asthma videos  
    NSW Asthma for Parents Resource Pack
    QLD Multilingual Factsheets

    Last updated July 2023

  • Reference List

    1. British guideline on the management of asthma, SIGN 158. Scottish Intercollegiate Guidelines Network and British Thoracic Society. 2019. (viewed February 2023)
    2. Di Palmo, et al. Asthma and Food Allergy: Which Risks? Medicina. 2019. 21:55(9), p509. doi: 10.3390/medicina55090509. PMID: 31438462; PMCID: PMC6780261
    3. Engelkes M, et al. Real-life data on incidence and risk factors of severe asthma exacerbations in children in primary care. Respiratory Medicine. 2016. Volume 119, p48-54.
    4. Foster SJ, et al. Oral prednisolone in preschool children with virus-associated wheeze: a prospective, randomised, double-blind, placebo-controlled trial. The Lancet: Respiratory Medicine. 2018. 6(2), p97-106.
    5. Papadopolous NG, et al. International Consensus ON (ICON) Pediatric Asthma. Allergy. 2012. 67(8), p 976–997.
    6. Keeney GE, et al. Dexamethasone for acute asthma exacerbations in children: a meta-analysis. Pediatrics. 2014. 133(3), p493-9.
    7. Kesavan S, et al. Is aerosol delivery by high‐flow nasal cannula in children an effective alternative to face mask aerosol nebulization? Editorial. Pediatric Pulmonology. 2019. 54, p1873–1874.
    8. Manti S, et al. Management of asthma exacerbations in the paediatric population: a systematic review. European Respiratory Society: Review. 2021. 30. 200367
    9. McNamara D, et al. New Zealand Child Asthma Guideline. Asthma and respiratory foundation NZ. 2020. (viewed February 2023)
    10. National Asthma Council Australia. Australian Asthma Handbook. National Asthma Council Australia, Melbourne, 2022. (viewed February 2023)
    11. Reddel HK, et al. Global Initiative for Asthma Strategy 2021. Respirology. 2022; 27, p14– 35.
    12. Robinson P, et al. Acute asthma exacerbation in children. BMJ Best Practice. Nov 2022.  (viewed February 2023)
    13. Singhi, S, et al. Randomised comparison of intravenous magnesium sulfate, terbutaline and aminophylline for children with acute severe asthma. Acta Paediatr. 2014. 103, p1301-1306.
    14. South Australian Paediatric Clinical Practice Guideline. Acute Asthma in children.;CACHEID=ROOTWORKSPACE-8169868040d035a79695be40b897efc8-oboz6K8 (viewed February 2023)
    15. Trottier ED, et al. Managing an acute asthma exacerbation. Canadian Paediatric Society. 2021. (viewed February 2023)
    16. Queensland Children’s Health. Asthma guideline. (viewed February 2023)
    17. Scarfone RJ, et al. Asthma management in children under 12 years of age in the emergency department. UpToDate. 2022. (viewed February 2023)
    18. Williams G. Asthma and wheeze, management of acute. Starship Clinical Guidelines. 2019. (viewed February 2023)
    19. Wilson MM, et al. A prospective evaluation of the 1-hour decision point for admission versus discharge in acute asthma. J Intensive Care Med. 2003. 18(5), p275-85. doi: 10.1177/0885066603256044. PMID: 15035763.
    20. Yung M, et al. Randomised controlled trial of aminophylline for severe acute asthma. Arch Dis Child 1998. 79(5), p405-10.