Cough is one of the most common chief complaints in primary care. The exam tests it heavily. And the candidates who struggle aren't lacking knowledge — they're lacking a systematic approach to sort the dozen possibilities into the right working diagnosis.
Here's the workup that has carried my students through the FNP exam and through real clinic days.
Every cough is a story. The history tells you the diagnosis before any test does.
The First Question: Acute or Chronic?
- Acute: <3 weeks. Usually infectious.
- Subacute: 3–8 weeks. Often post-infectious or early chronic process.
- Chronic: >8 weeks. Top causes: upper airway cough syndrome (post-nasal drip), asthma, GERD. Always check for ACE inhibitor use.
Pneumonia
Clinical clues
Fever, productive cough, pleuritic chest pain, dyspnea, focal exam findings (crackles, decreased breath sounds, dullness to percussion).
Outpatient management
If healthy, no comorbidities, no recent antibiotics:
- Amoxicillin 1g TID, OR doxycycline 100 mg BID, OR azithromycin (if local resistance <25%)
If comorbidities (heart, lung, liver, kidney disease, diabetes, alcohol use, immunosuppression):
- Respiratory fluoroquinolone (levofloxacin, moxifloxacin) OR combination beta-lactam (amoxicillin-clavulanate, cefpodoxime) + macrolide
CURB-65 to decide hospital admission
- C: Confusion
- U: Urea (BUN >19)
- R: Respiratory rate ≥30
- B: BP <90 systolic or ≤60 diastolic
- 65: Age ≥65
Score 0–1 = outpatient. 2 = consider admission. ≥3 = admit, possibly ICU.
Test Pearl: Don't get the chest X-ray for a routine outpatient pneumonia diagnosis unless symptoms are atypical or severity uncertain. Clinical diagnosis is acceptable in most outpatient cases.
Asthma
Diagnostic clues
Episodic wheezing, dyspnea, chest tightness, cough — often nocturnal or with triggers (cold air, exercise, allergens). Family history of atopy.
Diagnostic testing
Spirometry showing FEV1/FVC reduced with bronchodilator reversibility (≥12% improvement in FEV1).
Stepwise treatment (current GINA guidelines)
- Step 1–2: As-needed low-dose ICS-formoterol (current GINA preference). Or as-needed SABA + low-dose ICS.
- Step 3: Daily low-dose ICS-formoterol + as-needed ICS-formoterol (MART regimen).
- Step 4: Medium-dose ICS-LABA daily + as-needed.
- Step 5: Add-on therapies (LAMA, biologics — refer).
Asthma exacerbation
SABA (albuterol) — first action. Oral corticosteroids (prednisone 40–60 mg x 5–7 days). Consider hospitalization if PEF <50% predicted, severe symptoms, or no response to initial treatment.
COPD
Clinical clues
Progressive dyspnea, chronic cough, sputum production, history of smoking (or environmental/occupational exposure). Older patient typically.
Diagnostic criteria
Post-bronchodilator FEV1/FVC <0.70.
GOLD staging
- GOLD 1: FEV1 ≥80% predicted (mild)
- GOLD 2: FEV1 50–79% (moderate)
- GOLD 3: FEV1 30–49% (severe)
- GOLD 4: FEV1 <30% (very severe)
Management
- All patients: Smoking cessation, vaccinations (influenza, pneumococcal, COVID, Tdap, Shingrix), rescue SABA.
- Stable maintenance: LAMA (tiotropium) ± LABA. Add ICS if frequent exacerbations or asthma overlap, but be cautious — long-term ICS in pure COPD increases pneumonia risk.
- Pulmonary rehab for moderate to severe.
- Long-term oxygen if resting SpO2 ≤88% or PaO2 ≤55.
Acute exacerbation
SABA + SAMA, oral corticosteroids x 5 days, antibiotics if increased sputum purulence (azithromycin, doxycycline, amoxicillin-clavulanate).
Acute Bronchitis
Self-limited viral illness. Cough >5 days, sometimes purulent sputum (color is not a marker of bacterial infection). Treatment: supportive only. No antibiotics in healthy adults. The exam loves to test this — many candidates pick antibiotics when supportive is correct.
Upper Airway Cough Syndrome (Post-Nasal Drip)
Most common cause of chronic cough. Treatment: first-generation antihistamine-decongestant trial (chlorpheniramine, brompheniramine + pseudoephedrine) or intranasal steroid for allergic component.
GERD as a Cause of Cough
Especially in patients with reflux symptoms, hoarseness, or worsening cough lying down. Trial PPI for 8 weeks.
When to Refer or Order Advanced Workup
- Hemoptysis
- Cough >8 weeks with smoking history (consider lung cancer; CT chest if smoking 50–80, 20+ pack-years)
- Unexplained weight loss
- Failure to respond to empiric therapy
- Severe or progressive dyspnea
- Suspected interstitial lung disease, pulmonary embolism
The Strategy
For every cough question, ask: acute or chronic? Risk factors? Vital signs? Exam findings? Then narrow to 2 or 3 diagnoses. The exam rewards the candidate who systematically eliminates possibilities.