Asthma in Adults and Adolescents

Clinical Snapshot

Asthma is a heterogeneous, chronic inflammatory disorder of the airways characterized by paroxysmal or persistent respiratory symptoms — dyspnea, chest tightness, wheeze, and cough, often with sputum production — together with variable expiratory airflow limitation and airway hyperresponsiveness.^[1] Airway inflammation, not bronchospasm alone, is the core pathophysiology: it drives both the acute, largely reversible airflow limitation typical of asthma and, if poorly controlled over time, progressive structural airway changes. Symptoms characteristically vary in frequency and intensity as inflammation and airflow limitation worsen or improve, often in relation to identifiable triggers such as allergens, exercise, viral infection, or irritant exposure.^[2]

The target for asthma control, used identically by GINA and the Canadian Thoracic Society, is daytime symptoms on 2 or fewer days per week and reliever use on 2 or fewer doses per week, with no nocturnal symptoms and no limitation of normal activity.^[1]^[2] This chapter covers the diagnosis and stepwise pharmacologic and non-pharmacologic management of asthma in adults and adolescents (12 years of age and older), following the current GINA/Canadian Thoracic Society treatment-track framework for this age group; asthma management in younger children uses a different treatment continuum and dosing structure and is addressed separately.

Recognize the Condition

Typical presentation

Episodic or persistent dyspnea, chest tightness, wheeze, and cough, frequently worse at night or in the early morning, and precipitated or worsened by exercise, cold air, allergen exposure, viral upper respiratory infection, or irritant exposure. Symptoms are characteristically variable — better on some days than others — and often cluster into a recognizable trigger-related pattern (seasonal, occupational, exercise-induced, perennial).^[1]

Atypical or subtle presentation

Cough may be the only or predominant symptom (cough-variant asthma), particularly at night. Some patients report only chest tightness or a sensation of breathlessness without overt wheeze. A history of gradually reducing activity to avoid triggering symptoms is itself a clue to poorly controlled disease that patients often do not volunteer unprompted.

Examination findings

Wheeze on auscultation — which may be absent between exacerbations, and in a severe exacerbation with minimal air movement a "silent chest" is a red flag, not reassurance — nasal polyps, nasal congestion consistent with comorbid allergic rhinitis, and voice changes. The absence of crackles, unilateral wheeze, or digital clubbing helps distinguish asthma from alternative diagnoses such as bronchiectasis, a unilateral airway lesion, or interstitial lung disease.^[2]

Risk Factors

Family history of asthma or atopic disease (eczema, allergic rhinitis).
Personal history of atopy, allergic rhinitis, or eczema.
Environmental allergen exposure (house dust mite, pet dander, mould, seasonal pollen).
Occupational exposures and irritants — an important and under-recognized cause of new-onset asthma in adults; take a thorough occupational history in any adult presenting with new asthma symptoms.
Active or second-hand exposure to tobacco smoke, vaping, or cannabis smoke.
Viral respiratory infections.
Obesity.
Chronic rhinitis or rhinosinusitis.
Gastroesophageal reflux disease.
Anxiety and depression.
ASA or NSAID sensitivity, particularly in patients with nasal polyps or chronic rhinosinusitis (ASA-exacerbated respiratory disease).
Non-selective beta-blocker exposure, including ophthalmic formulations, which can precipitate bronchospasm.
Sulfite-containing food or drug preservatives.

Red Flags & Refer

Any of the following signs or patterns should prompt immediate emergency assessment or specialist referral rather than continued routine step-wise management:

Life-threatening exacerbation — silent chest, cyanosis, exhaustion, confusion or drowsiness, bradycardia, or an oxygen saturation below 90% despite supplemental oxygen: activate emergency care immediately.
Severe exacerbation — inability to complete a sentence in one breath, marked accessory muscle use, or a peak expiratory flow (PEF) less than 50% of predicted or personal best.
Any patient with a history of a near-fatal exacerbation (previous ICU admission, mechanical ventilation, or respiratory acidosis) — treat as very high risk for future life-threatening events and arrange close, structured follow-up.
Diagnostic uncertainty despite objective testing, or symptoms not responding to appropriately escalated therapy — reconsider alternative or coexisting diagnoses (vocal cord dysfunction, cardiac disease, bronchiectasis) rather than continuing to escalate asthma therapy alone.
Suspected occupational asthma.
Asthma not achieving control despite confirmed adherence, correct inhaler technique, and medium-to-high-dose inhaled corticosteroid-containing therapy — refer for phenotype assessment (blood eosinophils, FeNO, serum IgE) and consideration of biologic therapy.^[3]
Frequent need for oral corticosteroid courses, or any degree of long-term daily oral corticosteroid dependence for asthma control.
Pregnant patients with poorly controlled asthma — the risk of uncontrolled asthma to the pregnancy substantially exceeds the risk of standard controller therapy, and undertreatment in pregnancy is itself a red flag.

Assessment & Diagnosis

Distinguishing asthma from its most important mimic: COPD

Feature	Asthma	COPD
Typical age of onset	Often childhood or young adulthood, but can begin at any age	Usually over 40 years of age
Smoking history	Not required for diagnosis	Usually a significant smoking or biomass-exposure history
Symptom pattern	Episodic and variable, often clearly trigger-related	Chronic, slowly progressive dyspnea on exertion
Airflow limitation	Variable; often substantially or fully reversible	Persistent; rarely normalizes even with treatment
Spirometric bronchodilator response	Frequently ≥12% AND ≥200 mL increase in FEV1	May show partial reversibility but spirometry rarely normalizes
Day-to-day/diurnal variability	Prominent	Minimal
Personal/family history of atopy	Common	Not typical
Response to inhaled corticosteroids	Usually good	Variable; added mainly to reduce exacerbations in frequent exacerbators

Asthma-COPD overlap exists when a patient has features of both, particularly older patients with a long-standing asthma history who also smoke — see Special Populations below.

History

Family history of asthma and atopy.
Symptom frequency, severity, and timing, including nighttime versus daytime pattern.
Pattern of symptoms — seasonal, perennial, diurnal variation.
Precipitating factors — environmental allergens, occupational exposures, irritant smoke, ASA/beta-blocker exposure, sulfite preservatives, viral respiratory infections, exercise, rhinitis, sinusitis, gastroesophageal reflux, obesity, anxiety, depression.
Previous oral corticosteroid courses, emergency department visits, and any intensive-care admissions for asthma.

Objective testing

Spirometry is the preferred method of diagnosis — reduced expiratory flow rates with reversibility (an increase in FEV1 of at least 12% and at least 200 mL after a bronchodilator, or after a therapeutic trial of controller therapy, supports the diagnosis in adults).^[2]
Home peak flow monitoring — useful to help diagnose asthma when spirometry is unavailable, and to monitor patients with severe asthma or poor perception of airway obstruction.
Bronchoprovocation challenge testing (methacholine or histamine) in a lung function laboratory when the diagnosis remains in doubt after spirometry.
Biomarkers to guide treatment response and biologic eligibility in moderate-to-severe asthma — blood eosinophil count, fractional exhaled nitric oxide (FeNO), and serum IgE; these are not required for routine diagnosis of straightforward asthma.

When not to test: normal spirometry performed between symptomatic episodes does not exclude asthma — repeat testing when symptomatic, or proceed to bronchoprovocation challenge, rather than concluding the diagnosis is excluded from a single normal result.

Assessing asthma control at every visit

Control should be assessed at every clinical encounter using the following criteria; a patient meeting all of them is considered well controlled.^[2]

Characteristic	Well-controlled value
Daytime symptoms	≤2 days/week
Nighttime symptoms	Less than 1 night/week, and mild
Physical activity	Normal
Exacerbations	Mild and infrequent
Absence from work or school due to asthma	None
Need for reliever therapy (SABA or bud/form)	≤2 doses/week
FEV1 or PEF	≥90% of personal best

Risk factors for a severe exacerbation

Assessed separately from current symptom control, since a patient can be well controlled on therapy but still be at elevated exacerbation risk:

Any history of a previous severe exacerbation (requiring systemic steroids, an emergency department visit, or hospitalization) — the single strongest predictor of a future severe exacerbation.
Currently poorly controlled asthma.
Overuse of a SABA reliever (more than 2 inhalers of roughly 200 doses each per year).
Current smoking.
Reduced FEV1.
Comorbid atopic/allergic disease.

Treatment Targets

Prevent asthma-related mortality.
Prevent exacerbations.
Daytime symptoms on 2 or fewer days per week.
No nocturnal symptoms or night waking due to asthma.
Maintain normal activity levels, including the ability to exercise without limitation.
Need for reliever therapy on 2 or fewer occasions per week.
Normal or near-normal lung function.
Minimize medication adverse effects by using the lowest treatment step that maintains control.
Minimize or avoid maintenance oral corticosteroid exposure.

Choose Initial Treatment

Direct treatment rule

Preferred approach: Track 1 (ICS-formoterol reliever)

1st line, all adults and adolescents use Track 1 — as-needed low-dose budesonide/formoterol as the reliever at every step — rather than a SABA-based regimen, because it reduces the risk of severe exacerbations compared with a SABA reliever and is simpler, requiring only one inhaler and one inhaler technique across Steps 1-4.^[1]

For infrequent symptoms (roughly 1-2 days/week or less) or symptoms on fewer than 3-5 days/week with normal or only mildly reduced lung function, use Steps 1-2: anti-inflammatory reliever (AIR)-only — low-dose budesonide/formoterol taken solely as needed for symptom relief, with no separate daily maintenance dose.

For symptoms on most days, waking due to asthma once a week or more, or reduced lung function, use Step 3: maintenance-and-reliever therapy (MART) — low-dose budesonide/formoterol taken as a fixed daily maintenance dose plus additional as-needed doses for symptoms.

For daily symptoms, waking at night due to asthma once a week or more with reduced lung function, or in current smokers, use Step 4: MART with a medium maintenance dose of budesonide/formoterol.

For a patient presenting during an acute exacerbation who is not yet on regular controller therapy, start medium-dose MART (Step 4) immediately, in addition to treating the exacerbation itself.

Alternative approach: Track 2 (SABA or ICS-SABA reliever)

Use Track 2 — a conventional SABA (or, from Step 3 onward, an ICS-SABA combination) reliever paired with separate daily maintenance ICS-containing therapy — only when ICS-formoterol is unavailable or not covered by the patient's drug plan, or when a patient is already stable, adherent, and free of exacerbations on a daily ICS-containing regimen and prefers to continue it.^[1] Track 2 escalates from no maintenance therapy (Step 1, ICS taken with every SABA dose) through low-dose maintenance ICS (Step 2), low-dose (Step 3) and medium-dose (Step 4) maintenance ICS-LABA, to Step 5.

Escalation to Step 5 / severe asthma

Step 5 — refer for phenotype assessment when asthma remains uncontrolled despite confirmed adherence and technique at Step 4 (high-dose MART in Track 1, or medium-dose ICS-LABA in Track 2): obtain blood eosinophils, FeNO, and serum IgE, and consider add-on long-acting muscarinic antagonist (LAMA) therapy, a trial of high-dose maintenance ICS-formoterol, or biologic therapy selected by phenotype.^[3]

Reviewing and adjusting therapy

Review treatment every 3-6 months. Before stepping up therapy for apparently poor control, first confirm adherence, inhaler technique, and address contributing comorbidities (rhinitis, GERD, obesity) and ongoing trigger exposure — these are common, correctable causes of apparent treatment failure that should not simply be met with a higher dose.

Once total control has been maintained for at least 3 months (no exacerbations, no night waking, near-normal lung function, daytime symptoms or reliever use less than twice weekly), and the patient is not pregnant or about to travel away from available health care, consider stepping down — reduce the ICS dose by 25-50% at 3-month intervals while monitoring closely. Never stop ICS completely — complete cessation is associated with worsening control and exacerbations even in patients who appear well controlled.

Non-Pharmacologic Treatment

Identify and avoid precipitating factors — environmental allergens and occupational irritants specific to the patient.
Smoking and vaping cessation (including cannabis and substances other than tobacco) is essential; also advise avoidance of second-hand smoke exposure.
Treat modifiable comorbidities that worsen asthma control — obesity (nutrition, weight loss, regular physical activity), chronic rhinosinusitis, gastroesophageal reflux disease, obstructive sleep apnea, anxiety, and depression.
Allergen immunotherapy (subcutaneous or sublingual) can be considered as an adjunct to standard pharmacotherapy when there is clear evidence linking allergen exposure to persistent, suboptimally controlled symptoms. Do not initiate in a patient with poorly controlled asthma — severe, possibly fatal reactions are more frequent in this population. Do not use house dust mite sublingual immunotherapy if FEV1 is 70% predicted or less.^[1]
Home air cleaners/purifiers are not independently supported by evidence, although HEPA filtration may reduce some allergen levels as part of a broader environmental-control strategy.
Inhaler technique should be reviewed and observed at every encounter. Do not prescribe two different device types (for example a pMDI and a DPI) to the same patient, since this increases technique errors.
Provide every patient with a written asthma action plan describing daily preventive therapy, how to adjust reliever (and, for patients prone to exacerbations, controller) therapy for worsening symptoms, and when to seek urgent medical attention.
Annual influenza vaccination is recommended for all patients with asthma without contraindication; the live-attenuated influenza vaccine is contraindicated in patients who are pregnant or who have severe asthma (current oral or high-dose inhaled corticosteroid use, or active or recently medically-attended wheeze).
Pneumococcal vaccination is recommended for patients with a history of an asthma exacerbation requiring medical care in the past year, per current national immunization guidance.
Encourage patients with asthma to stay up to date with all age- and risk-appropriate vaccinations, including COVID-19 (with booster doses as recommended) and RSV vaccination for adults 60 years of age and older.
Bronchial thermoplasty — an endoscopic procedure using radiofrequency pulses to reduce airway smooth muscle — remains an experimental therapy available only at a small number of specialized centres, considered for severe asthma uncontrolled by persistent bronchial hyperreactivity when biologic therapy is not suitable, not effective, or not tolerated.

Pharmacologic Treatment Options

Drug / intervention	Role	Dose / use	Important adverse effects	Teaching points
Budesonide/formoterol (AIR-only) Preferred	Track 1, Steps 1-2 — anti-inflammatory reliever, no separate maintenance dose	1 inhalation PRN symptom relief; maximum 8 inhalations/day	Tremor, tachycardia, oral thrush, throat irritation	Same inhaler is used across every Track 1 step, which simplifies teaching and improves adherence.
Budesonide/formoterol (MART) Preferred	Track 1, Steps 3-5 — maintenance-and-reliever therapy	1-2 inhalations once or twice daily maintenance, plus 1 inhalation PRN; maximum 8 inhalations/day	Tremor, tachycardia, oral thrush, throat irritation	The only ICS-LABA product approved in Canada for reliever use — never substitute a different ICS-LABA combination into a MART regimen.
Low-dose ICS + SABA PRN Alternative	Track 2, Step 2 maintenance	Daily low-dose ICS (see Drug Tables for potency by molecule) plus salbutamol PRN	Oral thrush, dysphonia	Choose Track 2 only when ICS-formoterol is unavailable, not covered, or the patient is already stable and prefers their current regimen.
ICS-LABA maintenance Alternative	Track 2, Steps 3-4 maintenance	1 inhalation or 2 puffs BID depending on product (see Drug Tables)	Oral thrush, dysphonia, tremor, tachycardia	Never approved for reliever use in Track 2 (unlike budesonide/formoterol) — pair with a separate SABA or ICS-SABA reliever.
Salbutamol Special situation	Track 2 reliever, or backup reliever when budesonide/formoterol is not appropriate	1-2 puffs Q4-6H PRN, maximum 8 puffs/day	Tremor, tachycardia, palpitations, nervousness	Rising SABA use is a warning sign of poor control, not something to simply keep refilling.
Tiotropium (Respimat) Special situation	Step 5 add-on to ICS-containing therapy	2 inhalations (5 mcg total) once daily	Dry mouth, cough, urinary retention	Confirm the Respimat soft-mist formulation specifically — the HandiHaler capsule formulation is COPD-only and not approved for asthma.
Montelukast Alternative	Second-line to daily ICS or as-needed ICS-formoterol; add-on with comorbid allergic rhinitis	10 mg PO once daily at bedtime	Headache; neuropsychiatric effects including suicidal ideation	Less effective than ICS at preventing exacerbations. Counsel specifically on the neuropsychiatric warning.
Prednisone Special situation	Acute exacerbation, or self-management of a severe loss of control	25-50 mg PO once daily for 7-14 days (exacerbation)	Hyperglycemia, mood changes, insomnia, fluid retention	Give within 1 hour of presentation for a moderate-to-severe exacerbation; long-term daily use is a last resort only.
Omalizumab Special situation	Step 5 add-on — severe allergic asthma	150-375 mg SC every 2-4 weeks, individualized by weight and IgE	Injection-site reactions, headache; rare anaphylaxis	Requires a positive skin test or in vitro reactivity to a perennial aeroallergen and inadequate control on high-dose ICS.
Mepolizumab or benralizumab Special situation	Step 5 add-on — severe eosinophilic asthma	Mepolizumab 100 mg SC q4wk; benralizumab 30 mg SC q4wk x3 then q8wk	Headache, injection-site reactions	Selected by blood eosinophil count; can allow significant oral corticosteroid reduction.
Dupilumab Special situation	Step 5 add-on — eosinophilic/Type 2 asthma, or OCS-dependent	400-600 mg SC loading, then 200-300 mg SC q2wk	Injection-site reactions, transient eosinophilia	Also indicated for atopic dermatitis and chronic rhinosinusitis with nasal polyps in eligible patients.
Tezepelumab Special situation	Step 5 add-on — severe asthma regardless of phenotype	210 mg SC every 4 weeks	Pharyngitis, arthralgia, injection-site reactions	Broadest eligibility of the currently available biologics — no eosinophil or allergic-phenotype requirement.

Special Populations

Pregnancy

Pregnancy does not affect asthma in a predictable direction — some patients worsen, some improve, and some see no change, and the pattern tends to persist across subsequent pregnancies. What matters far more than the medications themselves is control: poorly controlled asthma in pregnancy is associated with preterm birth, low birth weight, pre-eclampsia, and placenta previa, while good control is associated with normal outcomes. Manage asthma in pregnancy using the same stepwise approach as in non-pregnant patients — do not under-treat out of medication-safety concerns.^[1]

SABAs and inhaled corticosteroids (particularly budesonide, which has the most extensive pregnancy safety data of any ICS) have been used extensively in pregnancy and are considered safe. Montelukast and LABAs (used with an ICS, never alone) have not shown adverse pregnancy effects in accumulating experience. Theophylline is considered safe but is rarely used given its narrow therapeutic index and lower efficacy. Data on biologic therapies in pregnancy remain limited; the risk of continuing or withholding biologic therapy must be individually weighed against the risk of uncontrolled severe asthma to the pregnancy.

Breastfeeding

Breastfeeding has no known effect on asthma severity. Bronchodilators (SABA, LABA, muscarinic antagonists) and both inhaled and oral corticosteroids are considered safe during breastfeeding. Montelukast is transferred into breast milk but is itself approved from 6 months of age. Data on biologic therapy during breastfeeding remain limited, and the established benefits of breastfeeding should be weighed against any theoretical risk.

Adolescents

Asthma control is often reduced in adolescents, and poor adherence to treatment is a major contributor. Contributing factors include: newly assumed responsibility for self-managing therapy, forgetfulness or being too busy to use an inhaler, social stigma around inhaler use, introduction of alcohol, cannabis, or tobacco use, emerging mental health comorbidities, and financial burden. Improve adherence in this group by regularly reviewing inhaler technique, matching device selection to patient preference and ease of use, considering a switch from SABA-based therapy to ICS-formoterol (Track 1), counselling on the respiratory risks of smoking and cannabis, and screening for comorbid mental health conditions.

Older adults

No specific dose adjustment is required for inhaled therapy based on age alone. Consider bone density and cataract/glaucoma risk when higher-dose ICS is needed long-term, and be alert to reduced inspiratory flow limiting dry powder inhaler effectiveness in frail patients.

Comorbid asthma and COPD

Patients with features of both asthma and COPD (asthma-COPD overlap) should receive sufficient ICS to control airway inflammation together with sufficient bronchodilator therapy to manage symptoms; therapy is individualized based on lung function, exacerbation history, symptoms, and eosinophil levels, and combination ICS/LABA ± LAMA therapy is often required.

Renal and hepatic impairment

Inhaled therapy has minimal systemic absorption and generally requires no renal or hepatic dose adjustment. Strong CYP3A4 inhibitors can meaningfully increase systemic exposure to several inhaled corticosteroids (see Drug Tables). No clinically important renal or hepatic dose adjustment has been established for the biologic agents based on current product information.

Monitoring & Follow-Up

Review symptom control and risk factors for exacerbation (see Assessment & Diagnosis) at every visit, and formally every 3-6 months once therapy is established. Review inhaler technique at every encounter — technique errors are common and directly associated with worse control. Repeat spirometry periodically to track lung function trajectory, and monitor growth velocity in adolescents on medium-to-high-dose ICS long-term. Consider bone density assessment in patients on long-term high-dose ICS or repeated oral corticosteroid courses. Check adherence at every visit, including refill patterns beyond the first fill, since non-adherence is a leading and correctable cause of apparent poor control. Confirm the written asthma action plan is current and that the patient understands when to step up self-management versus seek urgent care. Reassess vaccination status annually.

Treatment Failure / Next Step

Confirm the diagnosis is correct — reconsider alternative or coexisting diagnoses (vocal cord dysfunction, cardiac disease, bronchiectasis, uncontrolled rhinitis/GERD) before assuming this is simply undertreated asthma.
Check inhaler technique and adherence, including refill patterns, before escalating therapy — a large proportion of apparent treatment failure is technique or adherence failure, not true refractory disease.
Address contributing comorbidities (obesity, GERD, rhinosinusitis, anxiety/depression) and ongoing trigger or occupational exposure.
For self-managed worsening within a written action plan ("yellow zone"): on Track 1 (bud/form), increase to a maximum of 8 inhalations/day (or, in patients 16 years of age and older with a severe exacerbation in the past year, increase to up to 4 inhalations twice daily for 7-14 days); on Track 2 with a history of a severe exacerbation in the past year, a trial of a 4-fold or greater increase in maintenance ICS dose for 7-14 days is the 1st choice, with prednisone 30-50 mg once daily for at least 5 days as the 2nd choice. Seek urgent medical attention if there is no sustained improvement.^[2]
Step up within the current track, or switch tracks, per the algorithm — only after confirming steps 2-3 above.
If uncontrolled despite confirmed adherence on medium-to-high-dose ICS-LABA (± LAMA), obtain blood eosinophils, FeNO, and serum IgE, and refer for phenotype-guided biologic therapy.^[3]
Refer to a specialist for diagnostic uncertainty, suspected occupational asthma, or any history of a near-fatal exacerbation.

Common Errors to Avoid

Continuing SABA monotherapy in a patient with any risk factor for exacerbation.
Prescribing budesonide/formoterol as a reliever alongside a different, non-formoterol-containing ICS-LABA product — only budesonide/formoterol is approved for reliever/MART use.
LABA monotherapy without a concurrent inhaled corticosteroid.
Doubling the ICS dose empirically for worsening symptoms — evidence supports only a 4-fold-or-greater increase, and only in specific higher-risk patients with a history of severe exacerbation, not routine dose-doubling.
Completely stopping ICS once control is achieved — always step down gradually, never stop entirely.
Prescribing two different inhaler device types to the same patient, which increases technique errors.
Not reviewing inhaler technique at every visit.
Missing an occupational asthma workup in new adult-onset disease.
Uncautious ASA/NSAID use in a patient with nasal polyps, chronic rhinosinusitis, or known ASA-exacerbated respiratory disease.
Uncautious beta-blocker use, including ophthalmic formulations, which can precipitate bronchospasm.
Empiric antibiotics for an asthma exacerbation without evidence of bacterial infection.
IV aminophylline in the first hours of an acute severe exacerbation.
Targeting 100% oxygen saturation instead of the recommended 93-95% target during an exacerbation.
Delaying systemic corticosteroids beyond the first hour of presentation for a moderate-to-severe exacerbation.
Missing biologic-eligible severe asthma by not checking blood eosinophils, FeNO, or IgE in a patient uncontrolled on high-dose ICS-LABA.

Clinical Decision Algorithm

Track 1 (preferred): initial treatment selection by symptom pattern

Confirm asthma diagnosis objectively; classify symptom frequency, lung function, and exacerbation risk

Infrequent symptoms (~1-2 days/week) or under 3-5 days/week with normal/mildly reduced lung function

Steps 1-2: budesonide/formoterol low dose, AIR-only (as-needed only, no daily maintenance dose)

Symptoms most days, or waking due to asthma ≥1x/week, or reduced lung function

Step 3: budesonide/formoterol low-dose MART (fixed daily maintenance + as-needed extra doses)

Daily symptoms with night waking ≥1x/week and reduced lung function, or current smoker

Step 4: budesonide/formoterol medium-dose MART

Presenting during an acute exacerbation, not yet on regular therapy

Start Step 4 medium-dose MART immediately, in addition to treating the exacerbation

Not controlled despite Step 4, with adherence/technique/comorbidities confirmed and corrected

Step 5: refer for phenotype assessment (blood eosinophils, FeNO, IgE); consider high-dose MART, add-on LAMA (tiotropium Respimat), or phenotype-matched biologic therapy^[3]

Track 2 (alternative): when ICS-formoterol is not appropriate

ICS-formoterol unavailable/not covered, OR patient already stable, adherent, and exacerbation-free on daily ICS-containing therapy and prefers to continue it

Step 1: infrequent symptoms

SABA reliever only; if a controller is added, take a low dose of ICS with each SABA dose

Step 2

Daily low-dose maintenance ICS + SABA PRN

Steps 3-4

Daily low- (Step 3) or medium- (Step 4) dose maintenance ICS-LABA + SABA or ICS-SABA PRN — never bud/form as reliever with a non-formoterol ICS-LABA

Not controlled despite Step 4 with adherence/technique/comorbidities confirmed

Step 5: refer for phenotype assessment; consider add-on LAMA or biologic therapy, or switch to Track 1^[3]

Reviewing, stepping up, and stepping down

Reassess symptom control and exacerbation risk at every visit, formally every 3-6 months

Not well controlled

Check adherence, inhaler technique, comorbidities (rhinitis, GERD, obesity), and trigger exposure FIRST

True cause identified and corrected, still uncontrolled: step up within the current track, or switch tracks

Well controlled for ≥3 months, not pregnant, no imminent travel away from care

Consider stepping down: reduce ICS dose 25-50% at 3-month intervals, reassessing after each step

Never stop ICS completely, even once fully controlled

Acute exacerbation: self-management and urgent/emergency care

Worsening symptoms or falling peak flow at home

Track 1 (bud/form)

Increase to a maximum of 8 inhalations/day (or up to 4 inhalations BID x7-14 days if ≥16y with a severe exacerbation in the past year)

Track 2, ≥16y with severe exacerbation in past year

1st choice: 4-fold or greater ICS dose increase x7-14 days. 2nd choice: prednisone 30-50 mg once daily x≥5 days

No sustained improvement, or any red flag develops: seek urgent/emergency medical attention

Acute/urgent care: assess severity — ability to speak, respiratory rate, heart rate, SpO2, PEF

Mild-moderate

SABA via spacer or nebulizer, repeated as needed; add ipratropium if not improving; oxygen only if SpO2 under 93-95%; oral corticosteroid if risk factors present

Severe

SABA + ipratropium together (reduces admission risk); oxygen targeting 93-95% (not 100%); systemic corticosteroid within 1 hour of presentation; IV/nebulized magnesium sulfate if FEV1 under 25-35% predicted or not responding to initial treatment

Life-threatening

Silent chest, cyanosis, exhaustion, confusion, or bradycardia: treat as for severe exacerbation and escalate immediately for possible ICU-level care

Avoid: empiric antibiotics without evidence of bacterial infection; IV aminophylline in the first hours; 100% oxygen saturation as a target

Drug Tables

How to use this table: Doses are adult doses and require patient-specific confirmation (renal/hepatic function, weight, allergy history). Pediatric dosing is weight-based per the current product monograph unless stated. Drug pricing is intentionally omitted. Select any drug name to open its complete Pharmasist Drug Database page.

Short-acting beta2-agonists (SABAs)

Drug	Dosage	Adverse effects	Comments
Salbutamol	pMDI: 100 mcg/puff: 1-2 puffs Q4-6H PRN, maximum 8 puffs/day DPI (Diskus): 200 mcg Q4-6H PRN, maximum 800 mcg/day Nebules: 2.5-5 mg Q4-6H PRN	Tremor, tachycardia, palpitations, nervousness	Reliever only. Regular use above the recommended maximum is a marker of poor control and should prompt review of controller therapy, not continued escalation of SABA.
Terbutaline	DPI: 0.5 mg/inhalation: 1 inhalation Q4-6H PRN, maximum 6 inhalations/day	Tremor, tachycardia, palpitations, nervousness	Alternative SABA reliever; the dry powder device requires an adequate inspiratory flow.

Short-acting muscarinic antagonist (SAMA)

Drug	Dosage	Adverse effects	Comments
Ipratropium	pMDI: 20 mcg/puff: 2 puffs Q6-8H PRN, maximum 240 mcg/day Nebules: 250-500 mcg Q4-6H PRN	Dry mouth, metallic taste; mydriasis and acute angle-closure glaucoma if sprayed into the eye	Add-on therapy to a SABA for acute exacerbations only, not for routine daily maintenance. Slower onset but longer duration of action than a SABA.

SAMA/SABA combination (acute exacerbations only)

Drug	Dosage	Adverse effects	Comments
Ipratropium/salbutamol	Nebule: 0.5 mg ipratropium / 2.5 mg salbutamol per 2.5 mL unit-dose vial, by nebulization	Dry mouth, metallic taste, tremor, tachycardia, palpitations	Combined nebulized bronchodilation reduces the risk of hospital admission compared with a SABA alone in patients at higher risk during a severe exacerbation. Not for routine daily maintenance.

Long-acting beta2-agonists (LABAs) — never as monotherapy

Health Canada carries a boxed warning against LABA monotherapy in asthma; always pair with an inhaled corticosteroid.

Drug	Dosage	Adverse effects	Comments
Formoterol	DPI: 6-12 mcg Q12H, maximum 48 mcg/day	Tremor, tachycardia, palpitations, nervousness	Rapid onset of action. Used only for rescue when combined with budesonide in the same inhaler, or as add-on to another separately-taken ICS — never as a standalone reliever.
Salmeterol	DPI (Diskus): 50 mcg/inhalation: 1 inhalation BID	Tremor, tachycardia, palpitations, nervousness	Slow onset of action — not suitable for immediate symptom relief. Only prescribe when confident the patient will reliably use the prescribed ICS alongside it.

Inhaled corticosteroids (ICS), single agent — dosing categories by potency

Low/medium/high categories are Canadian-approved adult dosing tiers.

Drug	Dosage	Adverse effects	Comments
Beclomethasone dipropionate (HFA, extrafine)	Low dose: ≤200 mcg/day Medium dose: 201-500 mcg/day High dose: >500 mcg/day, maximum 800 mcg/day	Oral/throat irritation, dysphonia, oral candidiasis (reduce by rinsing the mouth or using a spacer)	Extrafine-particle formulation — not interchangeable milligram-for-milligram with older, non-extrafine beclomethasone products.^[2]
Budesonide	Low dose: ≤400 mcg/day Medium dose: 401-800 mcg/day High dose: >800 mcg/day, maximum 2400 mcg/day	Oral/throat irritation, dysphonia, oral candidiasis	Also available as nebules for patients unable to use a hand-held device; the Turbuhaler requires an adequate inspiratory flow. Preferred ICS when initiating therapy in pregnancy given the most extensive pregnancy safety data of any ICS.^[2]
Ciclesonide	Low dose: ≤200 mcg/day Medium dose: 201-400 mcg/day High dose: >400 mcg/day, maximum 800 mcg/day	Oral/throat irritation (generally lower incidence given prodrug activation in the lung)	Prodrug, biologically inert until activated by esterases in the lung; usually dosed once daily in the evening.^[2]
Fluticasone furoate	Low dose: 100 mcg/day High dose: 200 mcg/day, maximum daily dose	Oral/throat irritation, dysphonia, oral candidiasis	Once-daily dosing; no approved medium-dose option for this molecule.^[2]
Fluticasone propionate	Low dose: ≤250 mcg/day Medium dose: 251-500 mcg/day High dose: >500 mcg/day, maximum 2000 mcg/day	Oral/throat irritation, dysphonia, oral candidiasis	Available as both a pMDI (Flovent HFA) and a DPI (Flovent Diskus); also the ICS component of fluticasone propionate/salmeterol.^[2]
Mometasone furoate	Low dose: 100-200 mcg/day Medium dose: >200-400 mcg/day High dose: >400 mcg/day, maximum 800 mcg/day	Oral/throat irritation, dysphonia, oral candidiasis	Once- or twice-daily dosing depending on total dose; also the ICS component of formoterol/mometasone and indacaterol/mometasone.^[2]

ICS-formoterol (Track 1 anti-inflammatory reliever and MART)

The only ICS-LABA combination approved in Canada for reliever use; the same inhaler is used across every Track 1 step.

Drug	Dosage	Adverse effects	Comments
Budesonide/formoterol	Steps 1-2, AIR-only: 1 inhalation PRN symptom relief, may repeat after a few minutes if needed; maximum 8 inhalations/day Step 3, MART: 1 inhalation once or twice daily maintenance, plus 1 inhalation PRN; maximum 8 inhalations/day Steps 4-5, MART: 2 inhalations twice daily maintenance, plus 1 inhalation PRN; maximum 8 inhalations/day	Oral/throat irritation, oral candidiasis, tremor, tachycardia, palpitations	Do not substitute a different ICS-LABA product into a MART regimen — only budesonide/formoterol carries this indication in Canada.

ICS-LABA (Track 2 maintenance only — not for reliever use)

Drug	Dosage	Adverse effects	Comments
Fluticasone furoate/vilanterol	Maintenance: 1 inhalation once daily	Oral/throat irritation, oral candidiasis, tremor, tachycardia, palpitations	Once-daily dosing. Not approved for reliever use.
Fluticasone propionate/salmeterol	Diskus: 1 inhalation BID (100/50, 250/50, or 500/50 mcg strengths) pMDI: 2 puffs BID (125/25 or 250/25 mcg strengths)	Same class effects	Twice-daily dosing. Not approved for reliever use.
Formoterol/mometasone furoate	Maintenance: 2 puffs BID (100/5 or 200/5 mcg strengths)	Same class effects	Twice-daily dosing. Not approved for reliever use.
Indacaterol/mometasone furoate	Low-dose ICS: 1 capsule (150/80 mcg) inhaled once daily Medium/high-dose ICS: 1 capsule (150/160 or 150/320 mcg) inhaled once daily	Same class effects	Once-daily dosing; capsule strength selected by required ICS potency. Not approved for reliever use.

Long-acting muscarinic antagonist (LAMA) add-on

Drug	Dosage	Adverse effects	Comments
Tiotropium (Respimat)	Maintenance: 2 inhalations (2.5 mcg/actuation) once daily = 5 mcg/day	Dry mouth, cough, mydriasis and acute angle-closure glaucoma if sprayed into the eye, urinary retention	Add-on to ICS-containing therapy at Step 5 (or Step 4 in some patients). Confirm the Respimat soft-mist formulation — the HandiHaler capsule formulation is COPD-only and not approved for asthma.

Triple therapy (ICS/LABA/LAMA)

Indicated when asthma remains uncontrolled on ICS-LABA alone.

Drug	Dosage	Adverse effects	Comments
Fluticasone furoate/umeclidinium/vilanterol	Maintenance: 1 inhalation once daily (100/62.5/25 or 200/62.5/25 mcg strengths)	ICS, LABA, and LAMA class effects combined	Once-daily dosing.
Indacaterol/glycopyrronium/mometasone furoate	Maintenance: 1 capsule (150/50/160 mcg) inhaled once daily	Same class effects	Once-daily dosing.

Leukotriene receptor antagonist

Drug	Dosage	Adverse effects	Comments
Montelukast	Adults and adolescents: 10 mg PO once daily at bedtime	Headache, abdominal pain; neuropsychiatric effects including agitation, aggression, hallucinations, and suicidal ideation have been reported	Second-line to daily ICS or as-needed ICS-formoterol — less effective at preventing exacerbations. Consider as add-on therapy in patients with concomitant allergic rhinitis. Counsel specifically on the neuropsychiatric warning.

Methylxanthines

Uncommon in current North American practice given a narrow therapeutic index and multiple drug interactions.

Drug	Dosage	Adverse effects	Comments
Theophylline	Initial: 400-600 mg/day PO in 1-3 divided doses depending on the formulation used	Nausea, vomiting, abdominal cramps, headache, palpitations, CNS stimulation, arrhythmia at excess levels	Requires serum level monitoring. Titrate slowly in theophylline-naive patients. Levels are reduced by phenytoin, carbamazepine, and rifampin, and increased by macrolides, oral contraceptives, and quinolones; levels may rise if the patient stops smoking.

Systemic corticosteroids

Drug	Dosage	Adverse effects	Comments
Prednisone	Exacerbation: 25-50 mg PO once daily for 7-14 days Yellow-zone self-management (2nd choice, ≥16 years with a severe exacerbation in the past year): 30-50 mg PO once daily for at least 5 days	Fluid retention, hyperglycemia, increased blood pressure, increased appetite, mood changes, insomnia (short-term); adrenal suppression, osteoporosis, cataracts, myopathy (long-term)	Give within 1 hour of presentation for a moderate-to-severe exacerbation. Courses of 2 weeks or less generally do not require tapering. Long-term daily use should be a last resort at the lowest effective dose, with specialist referral.

Biologics — Anti-IgE

Initiate only with significant expertise in asthma management, and administer under supervision of a professional experienced in managing anaphylaxis.

Drug	Dosage	Adverse effects	Comments
Omalizumab	Maintenance: 150-375 mg SC every 2-4 weeks, individualized by body weight and pretreatment serum IgE level per the product monograph dosing table	Injection-site reactions, headache, sinusitis, viral upper respiratory infections; rare anaphylaxis	For moderate-to-severe persistent allergic asthma with a positive skin test or in vitro reactivity to a perennial aeroallergen, inadequately controlled on high-dose ICS-containing therapy.

Biologics — Anti-interleukin-5 / anti-IL-5 receptor

Drug	Dosage	Adverse effects	Comments
Mepolizumab	Maintenance: 100 mg SC every 4 weeks	Headache, injection-site reactions, nasal congestion, pharyngitis; rare hypersensitivity	For severe eosinophilic asthma uncontrolled on high-dose ICS-containing therapy, with a blood eosinophil count generally above 150 cells/mcL. Can allow significant reduction in maintenance oral corticosteroid dose.
Benralizumab	Loading: 30 mg SC every 4 weeks for the first 3 doses Maintenance: 30 mg SC every 8 weeks thereafter	Headache, injection-site reactions, nasal congestion, pharyngitis; rare hypersensitivity	For severe eosinophilic asthma uncontrolled on high-dose ICS-containing therapy, with a blood eosinophil count generally above 300 cells/mcL. Can allow significant reduction in maintenance oral corticosteroid dose.
Reslizumab	Maintenance: 3 mg/kg IV infusion every 4 weeks	Headache, injection-site reactions, nasal congestion, pharyngitis; rare hypersensitivity	For severe eosinophilic asthma uncontrolled on high-dose ICS-containing therapy, with a blood eosinophil count generally at or above 400 cells/mcL. Administered by IV infusion rather than subcutaneous injection.

Biologics — Anti-interleukin-4 receptor alpha

Drug	Dosage	Adverse effects	Comments
Dupilumab	Loading: 400 mg SC (600 mg if oral-corticosteroid-dependent) as a single dose, split across 2 injection sites Maintenance: 200 mg SC (300 mg if oral-corticosteroid-dependent) every 2 weeks	Injection-site reactions, oropharyngeal pain, transient blood eosinophilia, arthralgia	For moderate-to-severe eosinophilic or Type 2 asthma uncontrolled on ICS-LABA, or for patients requiring maintenance oral corticosteroids. Also approved for atopic dermatitis and chronic rhinosinusitis with nasal polyps in eligible patients. Not advised with a current or past blood eosinophil count of 1500 cells/mcL or above.

Biologics — Anti-thymic stromal lymphopoietin (anti-TSLP)

Drug	Dosage	Adverse effects	Comments
Tezepelumab	Maintenance: 210 mg SC every 4 weeks	Pharyngitis, arthralgia, injection-site reactions, headache	For severe asthma uncontrolled on high-dose ICS-containing therapy, regardless of eosinophil count or allergic phenotype — the broadest eligibility of the currently available biologics.

References

Global Strategy for Asthma Management and Prevention, 2025 update — Global Initiative for Asthma (GINA). GINA, 2025 update (updated November 2025)
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
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

Professional reference only. Apply clinical judgment and verify patient-specific decisions against current authoritative guidance and product information.