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Wheeze: Differential Diagnosis

Wheeze is a continuous, musical, high-pitched sound, typically louder on expiration, though it may occur during inspiration. It results from airflow through narrowed intrathoracic small-to-medium airways, caused by:

  • Bronchoconstriction

  • Mucosal edema/inflammation

  • Luminal obstruction (e.g., mucus, foreign body)

  • Occasionally, dynamic airway collapse during exhalation


Stridor, in contrast, is a predominantly inspiratory sound from upper airway obstruction (e.g., larynx, trachea).


While asthma and COPD are the most common causes in adults, wheeze is not pathognomonic of either. The differential diagnosis is broader in children due to congenital and infective causes.


Adult Wheeze: Differential Diagnosis


Category Condition Key Features & Diagnostic Clues
Airway Diseases Asthma Variable wheeze, triggers (cold, allergens), normal between attacks; ↑FeNO, +BDR, PEF variability

COPD Chronic cough, dyspnoea, smoking Hx, irreversible obstruction (↓FEV₁/FVC <0.7)

Bronchiectasis Chronic wet cough, recurrent infections, coarse crackles; HRCT: bronchial dilatation

ABPA Asthma + eosinophilia + central bronchiectasis; ↑IgE, Aspergillus IgG/IgE
Cardiac & Vascular Heart Failure (Cardiac Asthma)


 Wheeze + orthopnoea, oedema, crackles; ↑BNP, echo changes; improves with diuretics

PE Acute SOB, pleuritic pain, tachycardia; ↑D-dimer, CTPA confirms
Reflux/Upper Airway GORD-related Wheeze Worse after meals, lying flat; coexists with asthma; may respond to PPIs

Vocal Cord Dysfunction / ILO Inspiratory wheeze/stridor; exercise/emotion triggers; laryngoscopy diagnostic
Infective Causes Acute Bronchitis Transient wheeze with viral URTI; resolves spontaneously

LRTI / Pneumonia Fever, cough, wheeze; more in smokers, chronic lung disease; CXR shows consolidation

Pertussis Paroxysmal cough >2 wks, inspiratory whoop; PCR/culture +

TB Chronic cough, wt loss, night sweats; apical changes on CXR, AFB+
Functional Dysfunctional Breathing Dizziness, perioral tingling, sighing; normal spirometry; improves with retraining

Anxiety/Panic Hyperventilation, SOB, chest tightness; normal tests
Occupational/Environmental Occupational Asthma Work-related wheeze; better off-duty; PEF variability by exposure

Hypersensitivity Pneumonitis Bird/farmer’s lung; cough, SOB post-exposure; BAL: ↑lymphocytes
Systemic/Autoimmune EGPA Asthma + eosinophilia + vasculitis; ↑IgE, p-ANCA+
Structural/Obstructive Central Airway Obstruction Localised/fixed wheeze; flat flow-volume loop; CXR/CT diagnostic

Foreign Body Aspiration Sudden unilateral wheeze; choking Hx; bronchoscopy needed


Children wheeze more frequently than adults due to narrower, more compliant airways, making them more susceptible to obstruction during inflammation or infection.


“Approximately half of children have had at least one wheezing episode by age 6, depending on the cohort; for example, in the Tucson Children's Respiratory Study, 51.5% had never wheezed at age 6 (i.e., 48.5% had wheezed)


History Is Key


A detailed history helps distinguish between self-limiting viral wheeze, asthma, and structural or congenital causes:

  • Age of onset

  • Pattern (episodic vs persistent)

  • Triggering events (e.g., infections, exercise)

  • Sudden onset (suggests aspiration)

  • Feeding issues (suggests aspiration or reflux)

  • Family history (asthma, atopy)

  • Seasonality (viral vs allergic patterns


Age Group Condition Key Features & Diagnostic Clues
Children <5 Years Viral‑Induced Wheeze / Bronchiolitis RSV common; fever → cough, tachypnoea, expiratory wheeze ± crackles; improves in 7–10 days; recurrent episodes ↑asthma risk
Asthma (Young Children) ≥4 wheeze episodes/year, multi‑trigger symptoms; atopy/FHx; good response to SABA/ICS
Laryngomalacia Inspiratory stridor from birth; worse supine/feeding; resolves by 6–24 months
Tracheomalacia Inspiratory/expiratory noise; barking cough; recurrent infections; worsens crying/exertion
Vascular Ring / Sling Stridor, wheeze, dysphagia; positional change of symptoms; imaging diagnostic
Croup Barking cough, inspiratory stridor, low‑grade fever
Cystic Fibrosis Wet cough, steatorrhea, FTT, recurrent infections; sweat chloride ↑
Primary Ciliary Dyskinesia Neonatal distress, year‑round wet cough & nasal congestion, ±situs inversus
Foreign Body Aspiration Sudden unilateral wheeze; choking Hx; unilateral hyperinflation on CXR
Children 5–16 Years Asthma Polyphonic expiratory wheeze; variable symptoms; ↑FeNO ≥35 ppb; BDR ≥12%+200 ml; PEF variability ≥15%
Exercise‑Induced Bronchoconstriction Wheeze/SOB during or after exercise; normal baseline spirometry
Allergic Rhinitis Nasal congestion, sneezing, postnasal drip triggering cough/wheeze
Vocal Cord Dysfunction / ILO Inspiratory noise, throat tightness; triggered by exercise/stress; normal spirometry at rest
Persisting Laryngomalacia/Tracheomalacia Stridor ± wheeze; may persist into school age
Pertussis Paroxysmal cough >2 weeks + inspiratory whoop
Pneumonia Fever, cough, focal chest signs; wheeze in some
Cystic Fibrosis Chronic productive cough, FTT, recurrent infections; sweat test diagnostic
ABPA Poorly controlled asthma; ↑IgE (>1000 IU/ml), Aspergillus IgE/IgG+, central bronchiectasis


Key Exam Points: Wheeze Differential Diagnosis

  • History is key: Always ask about

    • Onset (sudden vs gradual)

    • Triggers (exercise, allergens, cold air, infection)

    • Associated features (e.g. urticaria, hypotension, feeding issues, night-time cough)


  • Critical clinical patterns:

    • Acute wheeze with urticaria or hypotension → Think anaphylaxis

    • Sudden unilateral wheeze in previously well child → Suggests foreign body aspiration

    • Chronic wheeze with nocturnal cough and reflux → Consider aspiration or GERD


  • Differentiate stridor vs wheeze:

    • Stridor = Inspiratory, upper airway (e.g. epiglottitis, croup)

    • Wheeze = Expiratory, lower airway (e.g. asthma, bronchiolitis)


  • Adults: Prioritise

    • Asthma

    • COPD

    • Cardiac causes (e.g. heart failure)

    • Airway obstruction (e.g. malignancy, vocal cord dysfunction)


  • Children: Consider

    • Asthma or viral-induced wheeze

    • Allergic or atopic triggers

    • Congenital anomalies (e.g. laryngomalacia)

    • Foreign body aspiration


  • Use age to guide your differential:

    • Under 5 years: Bronchiolitis, congenital airway abnormalities, cystic fibrosis

    • 5–16 years: Asthma, vocal cord dysfunction, allergic rhinitis

    • Adults/elderly: COPD, heart failure, PE, malignancy

  • Clinical tip: Not all wheeze is asthma – avoid over-treatment and consider structural, infective, and cardiac causes.


References

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