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Asthma

Clinical Subject Page

Asthma

Asthma is a chronic inflammatory disorder of the airways characterized by variable respiratory symptoms, variable expiratory airflow limitation, and airway hyperresponsiveness.

Also called

Bronchial Asthma

ICD-10

J45.909

Specialty

Pulmonology

Onset

Chronic

Reviewed

July 2026

On This Page

Overview

Asthma causes recurrent episodes of:

  • Wheezing
  • Shortness of breath
  • Chest tightness
  • Cough

Symptoms and airflow obstruction typically vary over time and in intensity. Airflow limitation is often reversible spontaneously or with treatment.

Etiology & Risk Factors

Etiology

it develops through a complex interaction between:

  • Genetic susceptibility
  • Environmental exposures
  • Airway inflammation
  • Immune system dysregulation

Risk Factors

  • Personal history of atopy
  • Allergic rhinitis
  • Atopic dermatitis
  • Family history of asthma
  • Exposure to tobacco smoke
  • Air pollution
  • Occupational exposures
  • Obesity
  • Viral respiratory infections
  • Exposure to allergens

Common Triggers

  • Viral respiratory infections
  • Exercise
  • Cold air
  • Allergens
  • Smoke
  • Air pollution
  • Strong odors
  • Occupational irritants
  • Emotional stress
  • Aspirin and NSAIDs in susceptible patients
  • Beta blockers

Pathophysiology

Flow Chart

Trigger exposure
⬇
Activation of inflammatory cells
⬇
Release of inflammatory mediators
⬇
Airway inflammation
⬇
Bronchial smooth muscle contraction
⬇
Mucosal edema + Increased mucus production
⬇
Airway narrowing
⬇
↑ Airway resistance
⬇
Variable expiratory airflow limitation
⬇
Wheezing + Dyspnea + Cough + Chest tightness

Chronic Disease

Persistent airway inflammation
⬇
Repeated airway injury
⬇
Airway remodeling
⬇
Structural changes and less reversible airflow limitation

Clinical Presentation

  1. Symptoms

    • Wheezing
    • Shortness of breath
    • Cough
    • Chest tightness

    Symptoms are often:

    • Episodic
    • Worse at night or early morning
    • Triggered by exercise
    • Triggered by allergens or irritants
    • Worse during viral respiratory infections

    Signs

    • Expiratory wheezing
    • Prolonged expiration
    • Tachypnea
    • Tachycardia
    • Accessory muscle use during severe attacks
    • Reduced air entry in severe obstruction

    Severe or Life-Threatening Features

    • Difficulty speaking
    • Severe respiratory distress
    • Altered mental status
    • Exhaustion
    • Cyanosis
    • Silent chest
    • Markedly reduced peak expiratory flow

History Taking

  • Ask about:

    • Wheezing?
    • Shortness of breath?
    • Cough?
    • Chest tightness?
    • When did symptoms start?
    • Are symptoms episodic?
    • Worse at night or early morning?
    • Exercise-related symptoms?
    • Known triggers?
    • Allergies or allergic rhinitis?
    • Atopic dermatitis?
    • Family history?
    • Smoking or vaping?
    • Occupational exposures?
    • Previous hospital admissions?
    • Previous ICU admission or intubation?
    • Current inhalers?
    • Frequency of reliever use?
    • Adherence to treatment?

Important Terms

  • 1. SABA Overreliance

    Frequent or excessive use of a short-acting beta₂-agonist (SABA), suggesting poor asthma control and increased risk of severe exacerbations and asthma-related death.

    2. Controller Medication

    Medication used to control airway inflammation and prevent future exacerbations. Inhaled corticosteroids (ICS) are the main controller treatment.

    3. Reliever Medication

    Medication used for rapid relief of asthma symptoms when needed. Examples include ICS–formoterol and, in appropriate regimens, SABA.

    4. Asthma Control

    Describes how well asthma is currently controlled based on daytime symptoms, night waking, reliever use, and activity limitation.

    5. Asthma Exacerbation

    An acute or subacute worsening of asthma symptoms and lung function that requires additional treatment.

    6. Difficult-to-Treat Asthma

    Asthma that remains uncontrolled because of potentially correctable factors such as poor adherence, incorrect inhaler technique, triggers, or comorbidities.

    7. Severe Asthma

    Asthma that remains uncontrolled despite optimized high-dose ICS–LABA therapy, or requires this treatment to remain controlled.

    8. MART / SMART Therapy

    Using a single ICS–formoterol inhaler for both maintenance treatment and symptom relief, helping reduce severe exacerbations.

Investigations

  • Spirometry

    Look for:

    • Obstructive airflow pattern
    • Reduced FEV₁/FVC ratio
    • Improvement after bronchodilator administration

    Bronchodilator Response

    Improvement in airflow after an inhaled bronchodilator supports the diagnosis of asthma.

    Peak Expiratory Flow (PEF)

    Useful for:

    • Demonstrating variable airflow limitation
    • Monitoring asthma
    • Detecting exacerbations

    Bronchoprovocation Testing

    Consider when:

    • Symptoms suggest asthma
    • Spirometry is normal
    • Diagnosis remains uncertain

    Additional Tests

    • Fractional exhaled nitric oxide (FeNO)
    • Blood eosinophil count
    • Allergy testing
    • Total or specific IgE when indicated

    Chest X-ray

    Not routinely required.

    Consider when:

    • Alternative diagnosis is suspected
    • Symptoms are atypical
    • Complications are suspected

Diagnosis

Asthma · Stepwise Diagnostic Approach — GINA 2023

1
Clinical history
Symptoms & pattern
2
Physical examination
Signs & triggers
3
Spirometry
Confirm obstruction
4
Reversibility testing
Bronchodilator / challenge
5
Exclude differentials
Rule out mimics
Step 1 — Clinical History
Cardinal symptoms — variable & episodic
Wheeze — high-pitched, expiratory; typically bilateral
Dyspnea — episodic shortness of breath, often at night or early morning
Chest tightness — recurrent, often described as a band around the chest
Cough — dry, often nocturnal; may be sole symptom (cough-variant asthma)
GINA diagnostic probability — more likely asthma if:
Symptoms vary over time and in intensity
Symptoms worse at night or early morning
Symptoms triggered by exercise, allergens, cold air, viral infections
Symptoms improve spontaneously or with bronchodilator
Risk factors & atopic history
Personal or family history of atopy — eczema, allergic rhinitis, food allergy
Occupational exposures — isocyanates, flour dust, latex (occupational asthma)
Drug history — NSAIDs (aspirin-exacerbated respiratory disease), β-blockers
Smoking history — may coexist with COPD (asthma-COPD overlap)
Age of onset — childhood onset favours atopic asthma; adult-onset may be non-atopic
Symptom-free intervals between episodes — important distinguishing feature from COPD
Step 2 — Physical Examination
During an episode
Bilateral expiratory wheeze on auscultation
Prolonged expiratory phase
Hyperinflated chest — increased AP diameter
Use of accessory muscles (scalene, sternocleidomastoid) in severe exacerbations
Tachypnoea and tachycardia during acute attacks
Silent chest — absence of wheeze in severe asthma = life-threatening; reduced air entry
Between episodes
Often completely normal — supports diagnosis of asthma over COPD
Signs of atopy: eczema, allergic rhinitis, nasal polyps
Nasal examination — polyps (aspirin-sensitive asthma)
Exercise challenge may provoke wheeze in exercise-induced asthma
Digital clubbing is NOT a feature of asthma — if present, investigate for alternative diagnosis
Step 3 — Spirometry
FEV₁/FVC ratio
<0.70
Obstructive pattern — FEV₁ reduced more than FVC. Required for diagnosis. <LLN (lower limit of normal) preferred in adults.
FEV₁ % predicted
<80%
Reflects degree of airflow limitation. Mild ≥70%, Moderate 50–69%, Severe <50%. May be normal between episodes — normal spirometry does not rule out asthma.
Peak expiratory flow (PEF)
≥20% variability
Diurnal variation ≥20% over 2+ weeks = supports asthma. Twice-daily measurements (AM lowest, PM highest). Useful when spirometry unavailable.
Important: Normal spirometry does not exclude asthma
If spirometry is normal but clinical suspicion is high — proceed to bronchial challenge testing (Step 4). Spirometry should ideally be performed when the patient is symptomatic.
Step 4 — Reversibility Testing
Bronchodilator reversibility test (BDR)
Give 400 mcg salbutamol (4 puffs via spacer) — repeat spirometry after 15–20 min
Positive (significant reversibility):
FEV₁ increase ≥12% AND ≥200 mL from baseline
Strongly supports asthma — distinguishes from fixed obstruction in COPD
Negative BDR does not exclude asthma — airway inflammation may prevent full reversibility during testing
Bronchial provocation / challenge testing
Used when spirometry is normal but asthma is suspected
Methacholine / histamine challenge — most sensitive; PC₂₀ ≤8 mg/mL = positive
Mannitol challenge — more specific; useful to detect exercise-induced bronchoconstriction
Exercise challenge — >10% fall in FEV₁ after 6–8 min standardised exercise = positive
Trial of ICS therapy — significant improvement in symptoms and lung function over 4–8 weeks supports diagnosis
FeNO (fractional exhaled NO) — ≥40 ppb supports eosinophilic airway inflammation; <25 ppb makes eosinophilic asthma less likely
Step 5 — Exclude Differential Diagnoses
Key differentials to exclude
COPD — older patient, heavy smoker, fixed obstruction, no reversibility, symptoms not variable
Vocal cord dysfunction (VCD) — inspiratory stridor, normal spirometry, responds to speech therapy not bronchodilators
Heart failure — bilateral crackles, orthopnea, elevated BNP, CXR shows cardiomegaly
Bronchiectasis — productive cough, recurrent infections, CT shows dilated airways
Foreign body aspiration — unilateral wheeze, onset after choking episode, especially in children
GERD-induced cough — cough without wheeze, worse after meals, responds to PPI
Hyperventilation syndrome — dyspnea + dizziness + paraesthesia; normal spirometry and O₂
Additional investigations when needed
CXR — hyperinflation in acute; exclude pneumonia, pneumothorax, malignancy
Full blood count — eosinophilia (>300 cells/μL) supports eosinophilic asthma
Total IgE + specific allergen IgE (RAST) — identifies atopic sensitisation
Skin prick testing — identifies allergen triggers (house dust mite, pollen, pet dander)
CT thorax (HRCT) — if bronchiectasis or interstitial lung disease suspected
Sputum eosinophils — ≥3% supports eosinophilic asthma; guides steroid response
Alpha-1 antitrypsin — if early-onset emphysema / COPD suspected in young non-smoker
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Related Topics

Management

Asthma · Stepwise Treatment — GINA 2023

Step 1
Intermittent
›
Step 2
Mild persistent
›
Step 3
Moderate persistent
›
Step 4
Severe persistent
›
Step 5
Very severe
›
Step 6
Refractory / add-on
1
Intermittent Asthma Mild intermittent
Symptoms <2 days/week • Nighttime awakenings <2/month • No limitation of activity • FEV₁ ≥80%
Preferred controller
No daily controller needed at this step
As-needed low-dose ICS-formoterol AIR / SYGMA approach
Budesonide-formoterol as needed — preferred over SABA alone (reduces exacerbation risk)
Reliever (as needed)
SABA — Salbutamol (albuterol) 100–200 mcg as needed
OR ICS-formoterol as needed — preferred in GINA 2023 (anti-inflammatory reliever)
SABA-only without ICS is no longer recommended as monotherapy — always pair with ICS
2
Mild Persistent Asthma Mild persistent
Symptoms >2 days/week but not daily • Nighttime awakenings 3–4/month • Minor activity limitation • FEV₁ ≥80%
Preferred controller (daily)
Low-dose ICS daily — first-line
Budesonide 200–400 mcg/day • Beclomethasone 100–200 mcg/day • Fluticasone 100–200 mcg/day
Alternative: LTRA (montelukast) — less effective than ICS; useful if ICS not tolerated
Reliever (as needed)
Low-dose ICS-formoterol as needed — preferred reliever (GINA 2023 Track 1)
OR SABA as needed (if ICS controller is already given separately)
3
Moderate Persistent Asthma Moderate persistent
Daily symptoms • Nighttime awakenings >1/week • Some activity limitation • FEV₁ 60–79%
Preferred controller
Low-dose ICS + LABA — first-line combination
Budesonide/formoterol • Fluticasone/salmeterol • Beclomethasone/formoterol
Alternative: Medium-dose ICS alone
Budesonide 400–800 mcg/day • Fluticasone 200–500 mcg/day
Alternative: Low-dose ICS + LTRA (montelukast)
Reliever (as needed)
Low-dose ICS-formoterol as needed — anti-inflammatory reliever (MART regimen)
OR SABA as needed if on separate ICS controller
MART (Maintenance And Reliever Therapy) = single inhaler ICS-formoterol for both maintenance and relief — reduces exacerbations significantly
4
Severe Persistent Asthma Severe persistent
Continual symptoms throughout day • Frequent nighttime awakenings • Extreme activity limitation • FEV₁ <60%
Preferred controller
Medium-to-high dose ICS + LABA — first-line
Budesonide 800–1600 mcg + formoterol • Fluticasone 500–1000 mcg + salmeterol
Add-on: LAMA (tiotropium) — improves FEV₁ and reduces exacerbations
Tiotropium 2.5 mcg via Respimat once daily — approved for adults with uncontrolled asthma
Consider: LTRA add-on (montelukast)
Reliever + additional
ICS-formoterol as needed — MART regimen preferred
Reassess adherence, inhaler technique, and triggers before escalating
Referral to specialist — rule out difficult-to-treat or severe asthma
Consider short course oral corticosteroids if severely uncontrolled
5
Very Severe / Specialist-referred Asthma Severe uncontrolled
Uncontrolled on Step 4 • Specialist evaluation essential • Biologic therapy considered • Phenotyping required
Preferred controller
High-dose ICS + LABA — maximise inhaled therapy
Add LAMA (tiotropium) — triple therapy
Biologic / targeted therapy — based on asthma phenotype:
Anti-IgE: Omalizumab — allergic asthma, elevated IgE
Anti-IL-5: Mepolizumab, Reslizumab — eosinophilic asthma (≥300/μL)
Anti-IL-5R: Benralizumab — eosinophilic asthma; depletes eosinophils rapidly
Anti-IL-4R: Dupilumab — eosinophilic & type 2 asthma; also for atopic dermatitis
Anti-TSLP: Tezepelumab — broadest biologic; effective across multiple phenotypes
Criteria for biologic therapy
Confirmed severe asthma diagnosis
Good adherence and correct inhaler technique documented
Triggers identified and managed (allergens, smoking cessation)
≥2 severe exacerbations in past year requiring OCS
Phenotyping: blood eosinophils, total IgE, FeNO, allergen sensitisation
Reassess response to biologic every 4 months — discontinue if no clear benefit after 12 months
6
Refractory / Add-on Therapies Last resort
Uncontrolled despite Steps 1–5 • All reversible causes excluded • Specialist centre mandatory
Oral corticosteroids (OCS)
Prednisolone 5–10 mg/day — lowest effective dose
Significant systemic side effects — osteoporosis, diabetes, adrenal suppression; use only after all other options exhausted
Always add bone protection (calcium + vitamin D, bisphosphonate)
Bronchial thermoplasty
Radiofrequency energy delivered via bronchoscope → reduces airway smooth muscle mass
For adults with severe uncontrolled asthma not responding to Step 5
3 sessions over 3 weeks; reduces exacerbations and ED visits
Other add-on options
Azithromycin 500 mg 3x/week — reduces exacerbations in non-eosinophilic severe asthma; monitor QTc
Theophylline (low-dose) — anti-inflammatory; narrow therapeutic window; rarely used now
Allergen immunotherapy (AIT) — subcutaneous or sublingual; selected allergic asthma; reduces sensitisation over time
Key principles — GINA 2023
Step up if asthma is uncontrolled after 1–3 months on current therapy. Confirm adherence and inhaler technique first before escalating.
Step down once asthma is well-controlled for ≥3 months. Reduce the last added medication first. Do not step down in pregnancy or before winter.
SABA-only monotherapy is no longer recommended by GINA 2023 — always pair reliever with ICS to reduce exacerbation risk and inflammation.
Treatment goal: minimal/no symptoms, no limitations, no exacerbations, normal FEV₁, and no side effects from medication.

Complications

-Asthma Excerbation :

  • Acute or subacute worsening of asthma symptoms and lung function.
  • Common symptoms: increasing dyspnea, wheezing, cough, and chest tightness.
  • Common triggers include viral respiratory infections, allergens, smoke, pollution, and poor treatment adherence.
  • Assess severity using:
    • Ability to speak
    • Respiratory rate
    • Heart rate
    • Oxygen saturation
    • Accessory muscle use
    • PEF or FEV₁ when possible
  • Initial treatment:
    • Repeated inhaled SABA
    • Oxygen if hypoxemic
    • Systemic corticosteroids
    • Ipratropium for severe exacerbations
  • Consider IV magnesium sulfate in severe cases with poor response to initial treatment.
  • Silent chest, exhaustion, altered consciousness, or worsening hypoxemia are life-threatening signs.
  • Severe deterioration may require ICU admission and ventilatory support.
  • Before discharge, review inhaler technique, adherence, controller treatment, triggers, and the asthma action plan.

-Other Complications :

  • Respiratory failure
  • Pneumothorax
  • Pneumomediastinum
  • Airway remodeling
  • Persistent airflow limitation
  • Reduced quality of life
  • Medication-related adverse effects
  • Death

Prognosis

  • Most patients can achieve good symptom control with appropriate treatment.
  • Prognosis depends on:
    • Disease severity
    • Frequency of exacerbations
    • Treatment adherence
    • Inhaler technique
    • Trigger exposure
    • Comorbidities
  • Severe asthma is associated with greater morbidity and risk of hospitalization.
  • Previous severe exacerbation, ICU admission, or intubation indicates increased future risk.

Key Points / Clinical Pearls

  • Asthma causes variable respiratory symptoms and variable expiratory airflow limitation.
  • Wheezing, dyspnea, cough, and chest tightness are the classic symptoms.
  • A normal examination does not exclude asthma.
  • Spirometry is the main objective test used in diagnosis.
  • Inhaled corticosteroid-containing therapy is central to long-term treatment.
  • Frequent reliever use suggests poor asthma control.
  • Always assess inhaler technique and treatment adherence before escalating therapy.