Asthma in Infants and Children
Clinical Snapshot
Asthma in infants and children shares the same underlying pathophysiology as adult asthma — chronic airway inflammation producing variable, often reversible airflow obstruction with recurrent cough, wheeze, chest tightness, and shortness of breath[1] — but the practical challenge in this age group is fundamentally different: a confident, spirometry-confirmed diagnosis is rarely possible under 6 years of age, because most preschool-age children cannot reliably perform the reproducible forced-exhalation maneuvers spirometry requires.[2] Diagnosis in young children instead depends on a structured clinical pattern — recurrent wheezing episodes, exclusion of alternative causes, and a documented, timely response to a trial of asthma therapy — rather than a single confirmatory test.[1]
This chapter covers asthma from infancy through 11 years of age, organized around the two age bands current guidelines treat differently: children 5 years of age and younger, in whom diagnosis, device technique, and approved dosing all differ substantially from older patients, and children 6 to 11 years of age, who are closer to the adult/adolescent framework but still require pediatric-specific dosing, devices, and product approvals. Asthma in patients 12 years of age and older follows a different treatment-track structure and is addressed separately in Asthma in Adults and Adolescents.
Recognize the Condition
Typical presentation
Recurrent episodes of wheeze, cough, and difficulty breathing, often triggered or worsened by viral upper respiratory infections but also occurring with exercise, laughing, crying, cold air, or allergen exposure. A cough that is paroxysmal, worse at night, or longer or more severe than a typical viral illness is a clue to airway hyperreactivity rather than a simple cold. A true acute wheezing episode, as distinct from other noisy breathing, typically lasts more than 24 hours.[1]
Wheeze phenotypes — useful for framing, not for individual prediction
Recurrent wheeze is common in children 5 years of age and younger, and several classification schemes have historically been used to describe it. A symptom-based classification distinguishes episodic wheeze (occurring only during discrete illness-associated periods, absent between episodes) from multiple-trigger wheeze (episodic wheeze plus symptoms between episodes, e.g., during sleep or with activity, laughing, or crying). A time-trend classification, applicable only retrospectively, describes transient wheeze (beginning and resolving before 3 years of age), persistent wheeze (beginning before 3 years and continuing past 6 years), and late-onset wheeze (beginning after 3 years of age). Neither classification has good predictive value for an individual child, and neither should be used to withhold a therapeutic trial from a child with a compatible clinical pattern — they are useful only for framing the discussion, not for making the diagnosis.[1]
History clues that support airway hyperreactivity
Ask caregivers specifically about: wheeze (a high-pitched whistling sound on breathing out, distinguished from other noisy breathing by direct observation or a video/audio recording whenever possible), dry cough or coughing spells, symptoms worse during sleep or after laughing, crying, or activity, chest retractions or laboured breathing during episodes, and how quickly symptoms improved after any reliever or corticosteroid already given.[1] A personal history of atopic dermatitis, food allergy, or allergic rhinitis, or a family history of asthma or allergic disease in a parent or sibling, supports the diagnosis but is neither required nor specific for it. A previous hospital admission for bronchiolitis, particularly RSV bronchiolitis, is a recognized risk factor for later asthma.
Examination findings
Look for intercostal or suprasternal retractions, hyperexpansion of the chest, wheeze on normal or forced breathing, and signs of comorbid atopic disease (atopic dermatitis, pale or boggy nasal turbinates). Findings that point away from asthma toward an alternative diagnosis include nasal polyps or digital clubbing at any age (consider cystic fibrosis), localized or unilateral wheeze (consider an inhaled foreign body or a congenital airway anomaly), and stridor or a weak voice that is absent at night (consider vocal cord dysfunction, typically in older children and adolescents).
Risk Factors
- Family history of asthma or atopic disease (eczema, allergic rhinitis, food allergy) in a parent or sibling.
- Personal history of atopic dermatitis, food allergy, or allergic rhinitis.
- Allergen-specific sensitization, particularly multiple early-life sensitizations.
- Previous hospital admission for bronchiolitis, particularly RSV bronchiolitis, in infancy.
- First- or second-hand exposure to tobacco smoke, vaping, or cannabis smoke.
- Recurrent viral upper respiratory infections and daycare attendance.
- Male sex — asthma onset is typically earlier in males than females in childhood.
- Prematurity or bronchopulmonary dysplasia.
- Obesity.
- Low socioeconomic status or low parental education level.
- Vitamin D deficiency.
- Environmental allergen exposure (house dust mite, pet dander, mould, seasonal pollen).
Red Flags & Refer
Any of the following should prompt immediate emergency care, urgent referral, or reconsideration of the diagnosis rather than continued routine step-wise asthma management:
- Life-threatening exacerbation — silent chest, cyanosis, drowsiness or confusion, exhaustion, or an oxygen saturation under 92% on room air that fails to improve with initial bronchodilator treatment: activate emergency care immediately.[1]
- Failure to respond to repeated bronchodilator treatment — a child with features of a severe exacerbation that do not resolve within 1-2 hours despite repeated inhaled short-acting beta2-agonist (SABA) dosing must be transferred for emergency assessment.[1]
- Respiratory arrest or impending arrest, or recurrence of severe exacerbation signs within 48 hours of a previous episode, particularly if oral corticosteroids have already been given.
- Any child younger than 2 years of age with signs of a severe exacerbation — the risk of dehydration and respiratory fatigue is higher at this age, so seek medical attention earlier than for an older child.[1]
- Any history of a previous near-fatal exacerbation (intensive care unit admission, mechanical ventilation, or respiratory acidosis).
- An alternative diagnosis is more likely than asthma — a first episode of wheeze in an infant younger than 12 months (usually bronchiolitis), failure to thrive, neonatal or very early onset of symptoms, vomiting associated with respiratory symptoms, continuous wheeze or a seal-like barking cough, focal lung or cardiovascular findings, digital clubbing, no association of symptoms with typical triggers, or lack of response to appropriately dosed and correctly administered asthma medication: investigate the alternative diagnosis rather than escalating asthma therapy.[1]
- Poor growth velocity while on inhaled corticosteroid therapy — reassess the dose, the diagnosis, and adherence/technique rather than assuming this is an unavoidable medication effect; refer for specialist or endocrinology input if growth velocity does not recover.
- A child not achieving control despite confirmed correct inhaler technique and adherence on moderate- or medium-dose inhaled corticosteroid therapy.
- Frequent courses of oral corticosteroids, 2 or more emergency department visits, or any hospitalization for asthma.
- Suspected occupational or environmental exposure driving symptoms (e.g., a specific daycare, home, or school exposure).
Assessment & Diagnosis
Differentiating asthma from its common childhood mimics
| Presenting feature | Consider instead |
|---|---|
| Cough and congested or runny nose for under 10 days, without wheeze or breathing difficulty | Viral upper respiratory tract infection |
| Cough with feeding, recurrent chest infections | Gastroesophageal reflux, with or without pharyngeal dysphagia |
| Sudden onset of symptoms, unilateral wheeze | Inhaled foreign body (also consider tuberculosis) |
| Protracted coughing paroxysms, often with a whoop and vomiting | Pertussis |
| Persistent wet cough | Protracted bacterial bronchitis; tuberculosis |
| Noisy breathing when crying or feeding; harsh cough | Tracheomalacia or laryngomalacia |
| Cardiac murmur, failure to thrive | Congenital heart disease |
| Preterm birth, symptoms present since birth | Bronchopulmonary dysplasia |
| Excessive cough and mucus production, gastrointestinal symptoms, failure to thrive | Cystic fibrosis |
| Cough and recurrent chest infections with neonatal respiratory distress, chronic ear infections, and persistent nasal discharge from birth | Primary ciliary dyskinesia |
| Noisy breathing, feeding difficulties | Vascular ring |
| Recurrent fever and infections, including non-respiratory infections | Primary immunodeficiency |
| Stridor or a weak voice, worse with activity, typically absent at night (older children and adolescents) | Vocal cord dysfunction |
Diagnosis in children 5 years of age and younger — the 3-criteria approach
Formal spirometry is not feasible in most children under 6 years of age, since it requires a reproducible forced-exhalation maneuver most preschoolers cannot perform reliably.[2] Diagnosis instead relies on a structured, 3-criteria clinical approach; all three must be met to confirm a diagnosis of asthma — if only 1 or 2 are met, record the working diagnosis as "suspected asthma" and reassess.[1]
Criterion 1, recurrent acute wheezing episodes: at least 2 acute wheezing episodes in the past 12 months, OR at least 1 acute wheezing episode plus asthma-like symptoms between episodes (interval symptoms, e.g., dry cough, coughing spells, or symptoms worse during sleep or after laughing, crying, or activity). Because parents may use the word "wheeze" for any noisy breathing, at least one episode should be confirmed as true expiratory wheeze by a trained health care provider directly observing the child, reviewing a recording, or by a caregiver convincingly describing or imitating the sound.[1]
Criterion 2, no likely alternative cause: based on a thorough history and examination, no other condition (aside from a concurrent viral respiratory infection) is likely to explain the symptoms — see the differential diagnosis table above.[1]
Criterion 3, timely clinical response to asthma treatment: confirmed improvement within 20-60 minutes of a SABA, or within 3-4 hours after SABA plus oral corticosteroids for a more severe episode; or a documented decrease in the frequency or severity of episodes and interval symptoms during a 2-3 month trial of daily inhaled corticosteroid (ICS) (e.g., fluticasone propionate 100-250 mcg/day or equivalent by pressurized metered-dose inhaler via spacer) plus as-needed SABA. Reduce the ICS dose to the minimum effective dose immediately once the trial has confirmed the diagnosis.[1]
Asthma is less likely when the child is younger than 12 months and this is a first wheezing episode (bronchiolitis is far more likely, and the younger the child, the higher the likelihood of an alternative diagnosis); when the only symptom is a productive cough; when there is no response to a SABA or ICS trial; or when the respiratory signs and symptoms are otherwise atypical.[1] Refer an infant younger than 12 months with 2 or more wheezing episodes for expert assessment, and refer whenever an alternative diagnosis is suspected or symptoms fail to respond to, or worsen during, an appropriately conducted treatment trial.
Diagnosis in children 6 to 11 years of age
Spirometry showing reversible airflow obstruction is the preferred method of confirming the diagnosis at this age, using the same principle as in adults — an increase in FEV1 of at least 12% after a bronchodilator or after a course of controller therapy.[2] Peak flow is an insensitive indicator in children, and a normal value does not exclude significant airflow limitation; where spirometry is unavailable or non-diagnostic, a positive bronchoprovocation challenge (methacholine) or a convincing symptomatic response to a treatment trial can support the diagnosis. Perform spirometry at least annually in every child 6 years of age and older who is using regular asthma medication, to track lung function over time and confirm ongoing control.[2]
Objective testing across the pediatric age spectrum
- Impulse oscillometry — an effort-independent test performed during quiet tidal breathing, usable from about 3 years of age, that can provide supportive evidence of reversible airway obstruction when spirometry is not feasible.
- Skin prick testing or allergen-specific IgE — to identify allergic sensitization contributing to symptoms; most useful in children with persistent or poorly controlled symptoms being considered for environmental control measures or, in older children, biologic therapy.
- Blood eosinophil count — to help guide treatment decisions in children with difficult-to-control asthma being considered for biologic therapy.
- Chest x-ray — not routine, but useful when the diagnosis is in doubt, to exclude a structural abnormality, an inhaled foreign body, or chronic infection.
When not to test: imaging and laboratory tests are not usually required to diagnose straightforward asthma in a young child with a classic history. A normal spirometry result performed between symptomatic episodes does not exclude asthma in an older child — repeat testing when symptomatic, or proceed to a bronchoprovocation challenge, rather than concluding the diagnosis is excluded.
Assessing exacerbation severity — the Pediatric Respiratory Assessment Measure (PRAM)
The PRAM score is a validated, 5-item clinical severity score for children 2-17 years of age presenting with acute wheeze or an asthma exacerbation, and is recommended to help standardize severity assessment and guide the intensity of treatment.[3]
| Criterion | 0 points | 1 point | 2 points | 3 points |
|---|---|---|---|---|
| Oxygen saturation | ≥95% | 92-94% | Under 92% | — |
| Suprasternal retraction | Absent | — | Present | — |
| Scalene muscle contraction | Absent | — | Present | — |
| Air entry | Normal | Decreased at the base | Decreased at the apex and base | Minimal or absent |
| Wheezing | Absent | Expiratory only | Inspiratory, with or without expiratory | Audible without a stethoscope, or silent chest |
Total score out of 12: 0-3 is mild, 4-7 is moderate, 8-12 is severe. Use the score alongside, never in place of, direct clinical assessment.[3]
Treatment Targets
- Prevent cough, wheeze, or shortness of breath that interferes with daytime activity, exercise, school or daycare attendance, growth and development, or sleep.
- Prevent exacerbations requiring emergency department visits, hospitalization, or courses of systemic corticosteroids.
- Limit reliever (SABA) use to 2 or fewer doses per week outside of pre-exercise dosing.
- Achieve normal or near-normal lung function where measurable (spirometry, 6 years of age and older).
- Maintain normal growth velocity while on inhaled corticosteroid therapy.
- Minimize medication adverse effects by using the lowest inhaled corticosteroid dose that maintains control.
- Support normal participation in play, sport, and school or daycare activities.
- Avoid unscheduled emergency care and repeated oral corticosteroid courses.
Choose Initial Treatment
Two pediatric treatment tracks
Children 5 years of age and younger
As-needed SABA alone if symptoms are infrequent; daily low-dose ICS started for symptoms more than twice weekly or after a qualifying exacerbation; doubled to medium-dose ICS before specialist referral. No combination ICS-LABA or ICS-formoterol product is approved for routine use at this age in Canada.
Children 6 to 11 years of age
As-needed SABA alone only when no risk factor for a severe exacerbation is present; daily low-dose ICS for most other children; step-up options include medium-dose ICS, a combination ICS-LABA product approved at this age, or an added LTRA. As-needed budesonide-formoterol is not yet Health Canada-approved under 12 years of age.
Before starting controller therapy
Confirm the diagnosis using the age-appropriate approach above before committing a child to long-term controller therapy — in a child 5 years of age or younger who does not yet meet all 3 diagnostic criteria, treat and document as "suspected asthma" with a defined reassessment plan rather than a confirmed long-term diagnosis.
Children 5 years of age and younger
Step 1 for a child with no more than 2 wheezing episodes per year and no interval symptoms, or symptoms averaging twice a week or less: as-needed inhaled SABA alone is sufficient; no daily controller is required.[1]
Step 2, start daily controller when symptoms average more than twice a week over a 1-month period, OR the child has had 1 or more exacerbations in the past 12 months requiring an acute care visit, a course of oral corticosteroids, or hospitalization: start daily low-dose ICS plus as-needed SABA, continued for at least 2-3 months before assessing response.[1]
Alternative Step 2, episodic viral-induced wheeze as-needed high-dose ICS at the onset of a viral illness only after a trial of regular daily low-dose ICS has already been tried first and the physician is confident the family will use the intermittent regimen appropriately; a leukotriene receptor antagonist (LTRA) is a further alternative with a generally smaller effect than daily ICS.[1]
Before increasing the dose: confirm inhaler and spacer technique, confirm adherence, and ask about ongoing allergen or tobacco/vape smoke exposure. Only then Step 3 — double the ICS dose to the medium tier — and reassess again after 2-3 months.[1]
Step 4, refer a child 5 years of age or younger who remains uncontrolled on medium-dose ICS, or in whom side effects are observed or suspected, to a pediatric asthma or respirology specialist; do not continue escalating ICS dose in primary care beyond this point.[1]
Children 6 to 11 years of age
Step 1 for a child with symptoms twice a week or less AND no risk factor for a severe exacerbation: as-needed SABA alone is acceptable. Do not use SABA alone in a child with any risk factor for a severe exacerbation (a previous severe exacerbation, excessive SABA use, comorbid atopic disease, or current or recent exposure to tobacco or vape smoke) even if currently well controlled — start daily low-dose ICS plus as-needed SABA instead.[4]
Step 2 for symptoms more than twice a week, or any risk factor for exacerbation: daily low-dose ICS plus as-needed SABA is the preferred regimen at this age in Canada, using a product with an approved pediatric indication (see Drug Tables). An LTRA is second-line to ICS and less effective at preventing exacerbations, but is an option when ICS truly cannot be used.
Not currently available in Canada at this age international evidence increasingly supports as-needed low-dose budesonide-formoterol (an "anti-inflammatory reliever" strategy) as an alternative to daily ICS in children 6-11 years of age, but budesonide-formoterol is Health Canada-approved only from 12 years of age — this strategy is off-label under 12 in Canada and should not be used as routine practice outside a specialist or research setting.[1]
Before stepping up: confirm inhaler technique and adherence, and address comorbidities and triggers. Then Step 3 options are to increase to medium-dose ICS, change to a combination ICS-LABA product with an approved pediatric indication at this age (see Drug Tables), or add an LTRA — individual response varies and more than one option may need to be tried.[2]
Step 4, refer a child 6-11 years of age not achieving control on moderate- or medium-dose ICS with correct technique and adherence to a pediatric asthma or respirology specialist for phenotype assessment and consideration of add-on tiotropium or biologic therapy.[5]
Reviewing therapy
Reassess symptom control and risk factors at every visit. Once control has been maintained for at least 3 months, step down to the lowest effective ICS dose — do not leave a child on a higher dose than needed once stable.
Non-Pharmacologic Treatment
- Advise caregivers to eliminate the child's exposure to tobacco smoke, vaping, and cannabis smoke — one of the highest-yield interventions in pediatric asthma.[2]
- Identify and reduce exposure to specific environmental allergens or irritants the child is sensitized to or reacts to; multi-component environmental interventions are more effective than a single measure alone.
- Educate caregivers, and the child when developmentally able, that asthma is a chronic condition requiring ongoing management even between symptomatic episodes, not just treatment of flare-ups.
- Device technique is a critical, ongoing adherence and efficacy factor at this age. Always use a pressurized metered-dose inhaler (pMDI) with a valved holding chamber or spacer, never a pMDI alone, in children of any age. Use a facemask for children younger than 3-4 years of age and switch to a mouthpiece as soon as the child can reliably form a seal and cooperate (typically 4-6 years of age) — a mouthpiece delivers more drug to the lower airway than a facemask.[1]
- Teach tidal-breathing technique: after each single actuation into the spacer, have the child take 5-6 normal breaths in and out through the mask or mouthpiece; only 1 puff should be actuated into the spacer at a time, and inhalation should start as soon as possible after actuation.[1]
- Shake any suspension-formulation inhaler (e.g., salbutamol) immediately before each actuation.
- If a facemask is used, fit it snugly around the mouth and nose to prevent drug loss and eye exposure, and clean the skin around the mouth and nose after each use.
- Wash plastic spacers periodically with detergent, without rinsing, and air dry, to reduce static charge that can reduce lung drug delivery; anti-static or metal spacers are less prone to this problem.
- Reserve nebulizers for the minority of children who genuinely cannot be taught effective spacer technique — a pMDI with spacer delivers medication at least as effectively as a nebulizer for both maintenance and exacerbation treatment, with faster administration and lower infection-transmission risk.[1]
- Provide caregivers with a written, individualized asthma action plan describing daily preventive therapy, how to recognize worsening control, how to use a reliever, and specific instructions for when to seek urgent medical care.
- Share the action plan and device instructions with daycare or school staff, and confirm a reliever inhaler is accessible during school or daycare hours.
- Oral bronchodilator syrups are not recommended — they have a slower onset of action and a higher rate of side effects than inhaled SABA and should not be substituted for an inhaled device.[1]
- Advise on current, locally recommended vaccinations for children with asthma — annual influenza vaccination, routine childhood immunizations, pertussis vaccination, and RSV immunoprophylaxis for eligible infants.
Special Populations
Infants younger than 12 months
A first episode of wheeze in an infant under 12 months of age is usually bronchiolitis, not asthma — the younger the infant, the higher the likelihood of an alternative diagnosis, and a confirmed asthma diagnosis is rarely made at this age.[1] Refer any infant with 2 or more wheezing episodes for expert assessment rather than committing to a long-term asthma diagnosis and controller therapy in primary care.
Pregnancy and breastfeeding
Not directly applicable — this chapter addresses infants and children with asthma. For asthma management specific to pregnancy and breastfeeding, see Asthma in Adults and Adolescents.
Renal and hepatic impairment
Inhaled therapy has minimal systemic absorption and generally requires no renal or hepatic dose adjustment in children. Montelukast requires no dose adjustment in mild-to-moderate hepatic impairment; data in severe hepatic impairment are limited.
Neurodevelopmental or cognitive conditions affecting device use
A child with a neurodevelopmental condition, motor impairment, or significant behavioural difficulty may need extra time, a caregiver-administered facemask-and-spacer technique well beyond the age at which peers switch to a mouthpiece, or occupational therapy input to achieve reliable drug delivery — do not assume poor control in this population reflects true refractory asthma before device technique has been directly observed and optimized.
Transition to adolescent and adult care
As a child approaches 12 years of age, anticipate the shift to the adult/adolescent treatment-track framework and product approvals (e.g., budesonide-formoterol becomes available as both a reliever and maintenance option at this age) — see Asthma in Adults and Adolescents. Use the transition period to reinforce self-management skills and independent device technique before the child takes over primary responsibility for their own therapy.
Monitoring & Follow-Up
Reassess symptom control and exacerbation risk factors at every visit, and formally at least every 3-6 months once therapy is established. Measure and plot height at every visit, or at least annually, in any child on regular inhaled corticosteroid therapy — an initial reduction in growth velocity is a recognized, usually non-progressive effect in the first 1-2 years of treatment, but persistent poor growth velocity should prompt reassessment of the dose, the diagnosis, and adherence/technique rather than being accepted as an unavoidable cost of treatment. Reassess inhaler and spacer technique at every visit, and reassess whether the child is developmentally ready to move from a facemask to a mouthpiece. Perform spirometry at least annually in children 6 years of age and older using regular controller therapy. Check adherence, including refill patterns, at every visit. Confirm the written asthma action plan is current, matches the child's current medications, and has been shared with school or daycare. Reassess vaccination status annually. Track the cumulative number of oral corticosteroid courses and emergency or urgent care visits over the past year — frequent courses warrant specialist referral and, over time, consideration of adrenal function and bone health.
Common Errors to Avoid
- Assuming spirometry is required to diagnose asthma in a child under 6 years of age — use the 3-criteria clinical approach (recurrent wheeze, exclusion of alternatives, timely treatment response) instead.
- Doubling or quadrupling the inhaled corticosteroid dose for a viral upper respiratory infection or a mild loss of control — pediatric trial evidence does not support this strategy, unlike the specific higher-risk adult scenario where it is sometimes used.
- Leaving a young child on a facemask well past the age they could switch to a mouthpiece, reducing lung drug delivery.
- Actuating more than one puff into a spacer before the child inhales, or delaying inhalation after actuation — both markedly reduce the dose actually delivered.
- Prescribing budesonide-formoterol, or any ICS-formoterol combination, as a reliever or maintenance-and-reliever regimen in a child under 12 years of age — not Health Canada-approved at this age.
- Withholding daily inhaled corticosteroid therapy from a child who is currently well controlled on as-needed SABA alone but has a genuine risk factor for a severe exacerbation — risk status, not only current symptom frequency, should drive the decision to start a controller.
- Missing an alternative diagnosis (foreign body aspiration, gastroesophageal reflux, cystic fibrosis, vocal cord dysfunction, primary ciliary dyskinesia) in a child not responding to correctly administered asthma therapy.
- Using an oral bronchodilator syrup instead of an inhaled short-acting beta2-agonist.
- Not measuring or tracking growth velocity in a child on long-term inhaled corticosteroid therapy.
- Adding routine oral corticosteroids to a self-management action plan for a child without a history of a severe exacerbation who is responding adequately to inhaled SABA at home.
- Skipping montelukast's neuropsychiatric boxed-warning counselling at first dispensing because the drug feels gentler than an inhaler.
- Continuing an ICS-LABA combination product that is not actually approved for the child's specific age.
- Not confirming inhaler/spacer technique and adherence before assuming a child has treatment-resistant or difficult-to-control asthma.
Clinical Decision Algorithm
Drug Tables
How to use this table: Every dose below is a pediatric, weight- or age-banded dose specific to infants and children through 11 years of age. Confirm each weight-based calculation against the child's current weight and the product monograph maximum before dispensing. For patients 12 years of age and older, follow the adult/adolescent dosing framework in Asthma in Adults and Adolescents. Drug pricing is intentionally omitted.
Short-acting beta2-agonists (SABAs)
| Drug | Dosage | Adverse effects | Comments |
|---|---|---|---|
| Salbutamol | Routine relief, pMDI (4-11 y): 2 puffs (200 mcg) 3-4 times daily as needed, maximum 6 puffs/day Routine relief, pMDI (6-11 y, per product labelling): 2 puffs TID-QID PRN, maximum 800 mcg/day Routine relief, nebules (5-12 y): 1.25-2.5 mg as a single dose, maximum 5 mg/dose, may repeat QID PRN Before exercise, all ages: 2 inhalations 5-10 minutes before exercise, protects for up to 2-4 hours Acute exacerbation, all pediatric ages: 4 or more puffs (one at a time) by pMDI+spacer, or 2.5 mg by nebulizer; for a moderate or severe exacerbation, repeat every 20 minutes up to 3 times, then reassess[1] | Tachycardia, palpitations, nervousness, tremor, hypokalemia, restlessness, dizziness, headache, nausea | Reliever only. Use above the recommended maximum is a marker of poor control and should prompt review of controller therapy, not continued escalation of SABA. pMDI plus spacer delivers medication as effectively as a nebulizer. |
| Terbutaline | DPI (6 years and older): 1 inhalation PRN, maximum 6 inhalations/day | Tachycardia, palpitations, nervousness, tremor, hypokalemia, restlessness, dizziness, headache, nausea | Alternative SABA reliever for children 6 years of age and older; the dry powder device requires an adequate inspiratory flow. |
Short-acting muscarinic antagonist (SAMA) — acute exacerbation adjunct only
Not for routine daily maintenance in children.
| Drug | Dosage | Adverse effects | Comments |
|---|---|---|---|
| Ipratropium | Acute exacerbation: 4 puffs (20 mcg/puff) by pMDI+spacer, or 0.25 mg by nebulizer, given with each SABA dose, up to 3 times[1] | Dry mouth, metallic taste; mydriasis and acute angle-closure glaucoma if sprayed into the eye | Add to SABA during a moderate or severe exacerbation, up to 3 doses; no proven added benefit beyond the initial 3 doses, including in children who are hospitalized or discharged. |
Inhaled corticosteroids (ICS), by age band
Low/medium/high categories are Canadian-approved pediatric dosing tiers, sourced from CTS 2021 Table 8. "n/a" means the molecule does not have an approved indication in that age band in Canada.
| Drug | Dosage | Adverse effects | Comments |
|---|---|---|---|
| Fluticasone propionate | Preschoolers (1-4 y), low dose: 100-125 mcg/day Preschoolers (1-4 y), medium dose: 200-250 mcg/day Children (6-11 y), low dose: ≤200 mcg/day Children (6-11 y), medium dose: 201-400 mcg/day Children (6-11 y), high dose: not routinely used — the maximum Health Canada-approved daily dose in children 4-16 years of age is 400 mcg/day; escalating further is a specialist-guided, above-label decision | Oral thrush, dysphonia (reduce by rinsing the mouth and using a spacer) | Health Canada-approved from 1 year of age — the only ICS with a pediatric indication this young. Standard preschooler instruction is 100 mcg BID by pMDI via a pediatric spacer with facemask.[2] |
| Budesonide | Nebules (3 months and older): 0.25-0.5 mg BID, may increase to 1 mg BID Children (6-11 y), low dose: ≤400 mcg/day Children (6-11 y), medium dose: 401-800 mcg/day Children (6-11 y), high dose: over 800 mcg/day, maximum 2400 mcg/day | Oral thrush, dysphonia | DPI approved from 6 years of age; nebules approved from 3 months of age for children unable to use a hand-held device. The Turbuhaler requires an adequate inspiratory flow.[2] |
| Beclomethasone dipropionate (HFA, extrafine) | Children (5-11 y), low dose: ≤200 mcg/day Children (5-11 y), medium dose: 201-400 mcg/day Children (5-11 y), high dose: over 400 mcg/day, specialist-guided | Oral thrush, dysphonia | Health Canada-approved from 5 years of age; the same dosing tier applies to a 5-year-old as to an older child in the 6-11 year band.[2] |
| Ciclesonide | Children (5-11 y), low dose: ≤200 mcg/day Children (5-11 y), medium dose: 201-400 mcg/day Children (5-11 y), high dose: over 400 mcg/day, maximum 800 mcg/day | Oral thrush (generally lower incidence given prodrug activation in the lung) | Health Canada-approved from 5 years of age; prodrug, biologically inert until activated by esterases in the lung, usually dosed once daily.[2] |
| Mometasone furoate | Children (4-11 y), low dose: 100 mcg/day Children (4-11 y), medium dose: 200 mcg/day up to under 400 mcg/day Children (4-11 y), high dose: 400 mcg/day or more, maximum 800 mcg/day | Oral thrush, dysphonia | Health Canada-approved from 4 years of age.[2] |
ICS-LABA combination — the only option approved under 12 years of age in Canada
Health Canada has not approved budesonide-formoterol, fluticasone furoate/vilanterol, formoterol/mometasone, or indacaterol/mometasone for use under 12 years of age — do not substitute any of these for the product below in a child 6-11 years of age.
| Drug | Dosage | Adverse effects | Comments |
|---|---|---|---|
| Fluticasone propionate / salmeterol | Diskus 100/50 mcg (4-11 y): 1 inhalation BID | Oral thrush, dysphonia, tremor, tachycardia | Add to daily ICS when low-dose ICS alone is insufficient at Step 3. Never use for reliever or rescue dosing. |
Long-acting muscarinic antagonist (LAMA) add-on
Specialist-initiated only, for a child not controlled on Step 3 therapy.
| Drug | Dosage | Adverse effects | Comments |
|---|---|---|---|
| Tiotropium (Respimat) | Children (6-11 y): 2 inhalations of 1.25 mcg/actuation once daily, 2.5 mcg total delivered dose | Dry mouth, cough, mydriasis and acute angle-closure glaucoma if sprayed into the eye | Approved as add-on therapy from 6 years of age. Confirm the pediatric-strength (1.25 mcg/actuation) cartridge is used, not the adult/adolescent strength. |
Leukotriene receptor antagonist
| Drug | Dosage | Adverse effects | Comments |
|---|---|---|---|
| Montelukast | 2-5 years: 4 mg (chewable tablet or oral granules) PO once daily at bedtime 6-14 years: 5 mg (chewable tablet) PO once daily at bedtime | Headache, abdominal pain, flu-like symptoms; boxed warning for neuropsychiatric effects (agitation, aggressive behaviour, nightmares or sleep disturbance, depression, suicidal thinking or behaviour) — discuss with every family at first dispensing and instruct them to stop the drug and seek medical attention immediately if these develop | Second-line to ICS and less effective at preventing exacerbations that require oral corticosteroids. Reduced montelukast levels with concurrent phenytoin, carbamazepine, phenobarbital, or rifampin. |
Systemic corticosteroids — acute exacerbation
A short course used occasionally for an exacerbation generally does not require a taper. Repeated or prolonged courses can affect adrenal function, bone health, and growth — track cumulative courses.
| Drug | Dosage | Adverse effects | Comments |
|---|---|---|---|
| Prednisolone (oral liquid) | General pediatric course (all ages): 1 mg/kg/day PO, maximum 50 mg/day, for at least 3-5 days Initial dose, children 5 years and younger: 1-2 mg/kg PO, maximum 20 mg for children under 2 years, 30 mg for children 2-5 years[1] | Increased appetite, mood or behavioural changes, transient hyperglycemia, GI upset | Preferred oral formulation for a child who cannot reliably swallow a tablet; dispense with the calibrated oral syringe provided, never a household teaspoon. |
| Prednisone | General pediatric course (all ages): 1 mg/kg/day PO, maximum 50 mg/day, for at least 3-5 days | Increased appetite, mood or behavioural changes, transient hyperglycemia, GI upset | Tablet formulation for an older child able to swallow tablets, or when crushed for administration; clinically interchangeable with prednisolone at equivalent doses. |
| Dexamethasone | Children 5 years and younger: 0.3-0.6 mg/kg PO, maximum 12 mg, single dose or per local protocol[1] Children 6-11 years: 0.3-0.6 mg/kg/dose PO; confirm the exact maximum (commonly capped around 16 mg) against local emergency department protocol, since this age band is not separately specified in current primary guidance | Similar to prednisone/prednisolone at this dose and duration | A single- or two-dose alternative to a multi-day prednisolone/prednisone course. |
| Methylprednisolone sodium succinate | Severe exacerbation, day 1: 1 mg/kg IV every 6 hours on day 1, then per specialist or inpatient protocol[1] | Same class effects; hyperglycemia, mood changes | IV formulation for a severe exacerbation or when oral administration is not tolerated. |
Additional adjunct therapy — severe acute exacerbation, emergency department setting
| Drug | Dosage | Adverse effects | Comments |
|---|---|---|---|
| Magnesium sulfate | Children 2 years of age and older: 40-50 mg/kg IV, maximum 2 g, infused over 10-20 minutes[1] | Hypotension, flushing, nausea | For a severe exacerbation not responding to initial bronchodilator therapy; infuse under continuous monitoring. |
Biologics — specialist-initiated, 6 years of age and older
Reserved for children with a confirmed asthma diagnosis whose disease is not controlled by the therapies above; initiate and monitor under specialist supervision, with expertise in managing anaphylaxis.
| Drug | Dosage | Adverse effects | Comments |
|---|---|---|---|
| Omalizumab | Maintenance: Dose individualized by body weight and pretreatment serum IgE level; SC every 2-4 weeks | Injection-site reactions, viral upper respiratory infections, headache, sinusitis; rare anaphylaxis | For children 6 years of age and older with moderate-to-severe allergic asthma inadequately controlled on ICS-containing therapy, with confirmed IgE-mediated sensitization. |
| Mepolizumab | Children 6-11 years: 40 mg SC every 4 weeks | Headache, injection-site reactions, nasal congestion, pharyngitis; rare hypersensitivity | For children 6 years of age and older with severe eosinophilic asthma inadequately controlled on medium-to-high-dose ICS plus an additional controller. |
| Dupilumab | Maintenance: Dose individualized by body weight per the product monograph; SC every 2-4 weeks | Injection-site reactions, transient eosinophilia, arthralgia | For children 6 years of age and older with moderate-to-severe eosinophilic or Type 2 asthma; also approved for atopic dermatitis in eligible children. |
References
- Global Strategy for Asthma Management and Prevention, 2026 update — Global Initiative for Asthma (GINA). GINA, 2026 update (May 2026)
- Canadian Thoracic Society 2021 Guideline update: Diagnosis and management of asthma in preschoolers, children and adults — Canadian Journal of Respiratory, Critical Care, and Sleep Medicine (Yang CL, Hicks EA, Mitchell P, et al.). Can J Respir Crit Care Sleep Med 2021;5(6):348-361
- The Preschool Respiratory Assessment Measure (PRAM): a responsive index of acute asthma severity — Journal of Pediatrics (Chalut DS, Ducharme FM, Davis GM). J Pediatr 2000;137(6):762-768
- The management of very mild and mild asthma in preschoolers, children, and adolescents — Paediatrics & Child Health (Yang CL, Zysman-Colman Z, Chétrit E, et al.). Paediatr Child Health 2024;29(2):122-126
- Recognition and management of severe asthma: A Canadian Thoracic Society position statement — Canadian Journal of Respiratory, Critical Care, and Sleep Medicine (FitzGerald JM, Lemiere C, Lougheed MD, et al.). Can J Respir Crit Care Sleep Med 2017;1(4):199-221
- Health Product InfoWatch, August 2020 — Singulair (montelukast): risk of serious neuropsychiatric events — Health Canada. Health Canada, August 2020
Professional reference only. Apply clinical judgment and verify patient-specific decisions against current authoritative guidance and product information.