About This Page
This is a clinician-written, evidence-based guide aligned to the MCC Examination Objectives. It is structured by clinical presentation — the way the MCCQE tests and the way patients actually present. Management reflects current Canadian guidelines (CMA, CFPC, CPS). Always cross-reference with institutional protocols and clinical judgment.
The Bottom Line
- Classify by duration: acute <3 weeks, subacute 3-8 weeks, chronic >8 weeks; this single step dramatically narrows the differential
- Acute cough is usually viral upper respiratory infection or acute bronchitis; antibiotics are not indicated unless pneumonia, pertussis, COPD exacerbation with bacterial features, or another bacterial syndrome is suspected
- Chronic cough with normal CXR is most often upper airway cough syndrome, asthma/cough-variant asthma, GERD, ACE inhibitor use, or non-asthmatic eosinophilic bronchitis
- Red flags requiring CXR or urgent workup: haemoptysis, dyspnoea, fever, hypoxia, weight loss, night sweats, recurrent pneumonia, smoking history, immunocompromise, or TB exposure
- For MCCQE1, management is not just medication: smoking cessation, occupational history, vaccination, antibiotic stewardship, and safety-netting are core Canadian primary care actions
Approach to the Presentation
The cough presentation is explicitly listed in the MCC objectives and is commonly tested through primary care vignettes. The safest approach begins with duration, severity, infectious symptoms, sputum, haemoptysis, dyspnoea, medication review, smoking/vaping exposure, occupational exposure, TB risk, and systemic features. In acute cough, the key decision is whether pneumonia or another serious condition is present. In chronic cough, perform CXR and spirometry where indicated, then pursue a stepwise empiric approach to common causes while investigating red flags. Choosing Wisely Canada strongly supports antibiotic stewardship for viral respiratory infections.
Differential Diagnosis
| diagnosis | likelihood | key features | distinguishing test |
|---|---|---|---|
| Pneumonia | must-not-miss | Cough with fever, rigors, dyspnoea, pleuritic pain, tachypnoea, hypoxia, focal crackles or bronchial breath sounds. Older adults may present with delirium or falls | CXR showing infiltrate; severity assessment and oxygenation guide site of care |
| Tuberculosis | must-not-miss | Cough >2-3 weeks, haemoptysis, weight loss, night sweats, fever, TB contact, travel or birth in high-incidence setting, shelter/incarceration exposure, immunocompromise | CXR + sputum AFB smear/culture and NAAT; notify public health if suspected |
| Lung Cancer | must-not-miss | New or changed chronic cough, haemoptysis, weight loss, hoarseness, recurrent pneumonia, smoking/asbestos exposure, clubbing, lymphadenopathy | CXR then CT chest and tissue diagnosis via bronchoscopy/CT-guided biopsy as appropriate |
| Pulmonary Embolism | must-not-miss | Cough may be dry or haemoptysis with sudden dyspnoea, pleuritic chest pain, tachycardia, hypoxia, VTE risk factors | Pre-test probability pathway + D-dimer or CTPA |
| Viral URI / Acute Bronchitis | common | Acute cough with rhinorrhoea, sore throat, hoarseness, low-grade fever, diffuse wheeze/rhonchi; cough can persist 2-4 weeks after viral infection | Clinical diagnosis; CXR not needed if vitals and lung exam are reassuring |
| Asthma / Cough-Variant Asthma | common | Episodic cough worse at night/early morning, triggers (cold air, exercise, allergens), wheeze or chest tightness may be absent | Spirometry with bronchodilator reversibility; methacholine challenge if spirometry normal and suspicion remains |
| Upper Airway Cough Syndrome | common | Postnasal drip sensation, throat clearing, nasal congestion, allergic rhinitis or sinus symptoms. Cobblestoning may be present | Clinical; response to intranasal corticosteroid, antihistamine, saline irrigation; sinus imaging only if complicated or refractory |
| GERD / Laryngopharyngeal Reflux | common | Chronic cough worse after meals or lying flat, heartburn, sour taste, hoarseness; cough may occur without classic reflux symptoms | Empiric lifestyle/PPI trial if reflux symptoms; pH monitoring/endoscopy if alarm features or refractory |
| ACE Inhibitor Cough | common | Dry persistent cough starting days to months after ACE inhibitor initiation; more common in women and non-smokers | Stop ACE inhibitor; cough typically improves within 1-4 weeks but can take up to 3 months. Switch to ARB if needed |
| Pertussis | less common | Paroxysmal cough, inspiratory whoop, post-tussive vomiting, prolonged cough; vaccinated adults may have atypical symptoms | Nasopharyngeal PCR early; serology later where available. Public health considerations and prophylaxis for contacts |
| Heart Failure | less common | Nocturnal cough, orthopnoea, PND, dyspnoea, crackles, oedema, elevated JVP. May be mislabelled as bronchitis | BNP/NT-proBNP, CXR, ECG, echocardiography |
Red Flags & Key History
Symptoms
Haemoptysis, weight loss, night sweats, fever, or persistent cough >8 weeks
Dyspnoea, hypoxia, pleuritic chest pain, or tachycardia — pneumonia, PE, pneumothorax, or HF
Immunocompromise, HIV risk, biologic therapy, transplant, or chronic corticosteroid use
TB contact, shelter exposure, incarceration, travel or birth in high-incidence country, Indigenous community outbreak context
Smoking/vaping history, asbestos/silica exposure, radon exposure, or occupational irritants
Cough worse at night/early morning or triggered by cold/exercise — asthma pattern
Postnasal drip, throat clearing, nasal congestion — upper airway cough syndrome
Signs
Focal crackles, bronchial breath sounds, dullness to percussion — pneumonia or effusion
Clubbing, supraclavicular lymphadenopathy, hoarseness — malignancy or chronic suppurative lung disease
Wheeze — asthma/COPD, but also consider heart failure, anaphylaxis, foreign body, or airway lesion
Tachypnoea, SpO2 <92%, hypotension, or confusion
Nasal mucosal oedema/cobblestoning — rhinitis/postnasal drip
Approach to Investigation
First-line
No routine tests for uncomplicated acute viral coughIf normal vitals, no dyspnoea/hypoxia, and no focal chest signs, supportive care is appropriate; avoid low-value antibiotics and imaging
CXRIndicated for red flags, abnormal vitals, focal lung findings, suspected pneumonia, haemoptysis, chronic cough, immunocompromise, or malignancy/TB risk
Pulse oximetryUseful in acute cough with dyspnoea, abnormal vitals, pneumonia, COPD/asthma, or frailty
Medication and exposure reviewACE inhibitors, vaping/cannabis, occupational irritants, allergens, animals/birds, mould, dust, silica, asbestos
Second-line
Spirometry with bronchodilator responseFor chronic cough, suspected asthma/COPD, recurrent bronchitis, exertional symptoms, or wheeze
Sputum testingSputum culture if severe pneumonia, recurrent infection, bronchiectasis, immunocompromise, or treatment failure. AFB smear/culture/NAAT if TB suspected
CBC +/- inflammatory markersNot required for simple viral cough; useful if pneumonia, malignancy, systemic disease, anaemia, or immunocompromise suspected
Pertussis PCREarly in illness if paroxysmal cough, post-tussive vomiting, outbreak exposure, infant/pregnancy contact risk, or public health relevance
Specialist
CT chestPersistent abnormal CXR, suspected malignancy, bronchiectasis, ILD, unexplained haemoptysis, or chronic cough refractory to usual pathway
BronchoscopySuspected endobronchial lesion, foreign body, persistent haemoptysis, or unexplained focal radiographic abnormality
Methacholine challenge / FeNO where availableIf cough-variant asthma suspected but baseline spirometry is normal
Management Principles
MCC Cough Objective + Choosing Wisely Canada antibiotic stewardship + Canadian Thoracic Society asthma/COPD guidance1
Acute uncomplicated cough / viral bronchitis
- Reassure: cough commonly persists 2-4 weeks after viral infection
- Supportive care: fluids, honey for adults/children >1 year, analgesics/antipyretics, saline, humidification if helpful
- Avoid antibiotics unless bacterial pneumonia, pertussis, COPD exacerbation with bacterial features, or another bacterial syndrome is suspected
- Safety-net: return for dyspnoea, persistent fever, haemoptysis, chest pain, worsening after initial improvement, dehydration, or symptoms beyond expected course
2
Chronic cough with normal CXR
- Stop ACE inhibitor if present and switch to ARB if clinically appropriate
- Treat upper airway cough syndrome: intranasal corticosteroid, antihistamine strategy depending on allergic vs non-allergic rhinitis, saline irrigation
- Assess/treat asthma: spirometry; inhaled corticosteroid-containing therapy if asthma confirmed or highly suspected
- Treat reflux symptoms: lifestyle measures, weight management, avoid late meals; PPI trial if typical GERD symptoms or high suspicion
3
Specific serious causes
- Pneumonia: site-of-care decision, empiric antibiotics based on severity/comorbidity/local resistance, follow-up imaging if risk factors or incomplete resolution
- TB: airborne precautions if infectious, sputum AFB/NAAT/culture, notify public health, specialist/public health-directed multidrug therapy
- Suspected malignancy: urgent CT chest and referral through provincial lung cancer diagnostic pathway where available
Complications & Pitfalls
- Antibiotic reflex: Acute bronchitis is usually viral; unnecessary antibiotics cause adverse effects and antimicrobial resistance.
- Missing TB: Chronic cough with night sweats, weight loss, haemoptysis, or exposure risk requires TB testing and public health involvement.
- No CXR in chronic cough: Chronic cough >8 weeks generally warrants CXR before empiric cycling through therapies.
- ACE inhibitor delay: ACE inhibitor cough may begin months after starting therapy and may take weeks to resolve after stopping.
- Assuming wheeze equals asthma: Wheeze with cough can occur in COPD, heart failure, anaphylaxis, foreign body, or central airway obstruction.
MCCQE1 Exam Tips
- 1The MCC cough objective specifically expects duration classification: acute, subacute, chronic. Start there
- 2Uncomplicated acute bronchitis = no antibiotics. Choosing Wisely Canada-style antibiotic stewardship is highly testable
- 3Chronic cough + normal CXR + non-smoker = think upper airway cough syndrome, asthma, GERD, ACE inhibitor
- 4Cough + haemoptysis + weight loss/night sweats = TB or malignancy until proven otherwise
- 5Pertussis clue: paroxysms, whoop, post-tussive vomiting, prolonged cough, outbreak or infant contact risk
- 6A normal lung exam does not exclude pneumonia in older adults, but abnormal vitals increase the need for CXR
- 7CanMEDS health advocate: ask about occupational exposures and work-related cough; advising on workplace exposure is part of the MCC objective
practicetest your knowledge on coughApply what you've learnt with MCCQE1-style questions from the iatroX Q-Bank — respiratory and beyond.
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