Cough
Exam Tips
- Classify by duration first (<3, 3-8, >8 weeks) and then actively screen for red flags before symptomatic treatment.
- In OSCE history, always ask smoking exposure, ACE-inhibitor use, reflux/upper-airway symptoms, occupational triggers, and cancer alarm symptoms.
- For urgent escalation, remember severe features: suspected PE/pneumothorax, SpO2 <92% (without chronic baseline hypoxia), exhaustion/accessory muscle use, or haemodynamic instability.
- CRB-65 helps decide admission risk in community-acquired pneumonia (confusion, respiratory rate >=30, low BP, age >=65).
- Do not routinely prescribe antibiotics, oral steroids, bronchodilators, or inhaled steroids for uncomplicated acute viral cough without underlying airway disease.
- Chronic cough is often multifactorial; exam answers score well when you propose parallel treatment of more than one likely cause plus follow-up of response.
Definition
Cough is a protective respiratory reflex caused by stimulation of airway sensory receptors and coordinated brainstem motor output to clear secretions, irritants, or aspirated material. In adults, it is classified by duration as acute (<3 weeks), subacute (3-8 weeks), and chronic (>8 weeks), and this timeline helps structure differential diagnosis and management in UK practice.
Pathophysiology
Airway epithelial irritants, inflammation, mucus, refluxate, or mechanical distortion activate vagal afferents (including rapidly adapting receptors and C-fibre pathways) from larynx to distal bronchi. Signals are integrated in the medullary cough network, then an efferent sequence (deep inspiration, glottic closure, high intrathoracic pressure, explosive expiration) generates cough. In chronic cough, peripheral and central neural sensitisation (cough hypersensitivity syndrome) lowers the trigger threshold, so thermal, chemical, or mechanical stimuli provoke disproportionate coughing even when structural disease is limited. Common mechanistic drivers are upper airway inflammation/post-nasal drip, eosinophilic airway inflammation (asthma/eosinophilic bronchitis), gastro-oesophageal reflux (microaspiration and vagal reflex), tobacco smoke exposure, and ACE-inhibitor bradykinin/substance P effects. See figure reference: cough reflex arc and vagal pathways in standard respiratory physiology diagrams.
Risk Factors
- Current or passive cigarette smoke exposure
- Female sex (chronic cough more common in women)
- Age in the fifth to sixth decade
- ACE inhibitor therapy (higher risk also reported in people of Chinese ethnicity)
- Recent viral upper respiratory tract infection
- Underlying asthma, COPD, bronchiectasis, or interstitial lung disease
- Upper airway disease (rhinitis/sinusitis/post-nasal drip)
- Gastro-oesophageal reflux disease
- Occupational or environmental inhaled irritants
Clinical Features
Symptoms
- Dry or productive cough (timing and duration are diagnostically important)
- Throat irritation, frequent throat clearing, globus/post-nasal drip sensation
- Wheeze, breathlessness, chest tightness (suggesting asthma/COPD)
- Pleuritic chest pain or sudden dyspnoea (consider PE or pneumothorax)
- Cough worse after meals, talking, or bending (suggesting reflux-related cough)
- Morning cough in smokers
- Systemic symptoms: fever, myalgia, weight loss, malaise
- Red flags: haemoptysis, persistent hoarseness, dysphagia, vomiting, severe breathlessness
Signs
- Fever, tachycardia, tachypnoea, hypoxia, or central cyanosis in severe illness
- Focal chest signs (dull percussion, bronchial breathing, coarse crackles) suggesting pneumonia
- Wheeze/prolonged expiratory phase in obstructive airways disease
- Reduced unilateral breath sounds/chest expansion (pneumothorax)
- Tracheal deviation, hypotension, collapse in tension pneumothorax
- Nasal inflammation, visible posterior pharyngeal mucus, cobblestoning in upper airway cough syndrome
- Peripheral oedema with weight gain (possible heart failure)
Investigations
Management
Lifestyle Modifications
- Explain expected illness course: many acute coughs are self-limiting and may last up to 3-4 weeks
- Smoking cessation support (behavioural support plus pharmacotherapy where appropriate)
- Hydration, rest, and trigger avoidance (cold air, aerosols, workplace irritants)
- Safety-netting: seek urgent review for red flags (haemoptysis, worsening dyspnoea, chest pain, confusion, persistent fever, hypoxia)
- Review current medicines and stop likely culprits (notably ACE inhibitors) when clinically appropriate
Pharmacological Treatment
Simple analgesic/antipyretic for associated viral URTI symptoms
- Paracetamol 1 g orally every 4-6 hours as needed (maximum 4 g in 24 hours)
Use lower maximum doses in low body weight/frailty or liver impairment; avoid unintentional overdose from combination cold remedies.
NSAID option for pain/fever (if suitable)
- Ibuprofen 200-400 mg orally three times daily with food (usual OTC maximum 1.2 g/day)
Avoid/caution in peptic ulcer disease, CKD, heart failure, anticoagulant use, NSAID-sensitive asthma, and pregnancy (especially 3rd trimester).
Over-the-counter antitussive/expectorant (limited evidence; selected patients)
- Dextromethorphan 15-30 mg every 6-8 hours (maximum 120 mg/day)
- Guaifenesin 200 mg every 4 hours as needed (maximum 2.4 g/day)
Use short term only; avoid dextromethorphan with MAOIs and use caution with serotonergic drugs (serotonin toxicity risk). Counsel on sedation/misuse potential.
Cause-directed treatment: ACE inhibitor cough
- Stop ACE inhibitor and switch to an ARB, e. g, losartan 50 mg once daily (titrate by BP/renal function)
Cough usually improves over days to weeks after withdrawal; monitor renal function and potassium after RAAS drug changes.
Cause-directed treatment: suspected asthma/eosinophilic airway disease
- Salbutamol 100-200 micrograms inhaled as needed
- Budesonide 200-400 micrograms inhaled twice daily (or equivalent ICS regimen)
Confirm diagnosis with objective testing where possible; step treatment per asthma guidance; check inhaler technique and adherence.
Cause-directed treatment: reflux-associated cough (when clinically likely)
- Omeprazole 20 mg orally once daily for 4-8 weeks
Best in patients with reflux symptoms; review ongoing need to reduce long-term PPI adverse effects (fracture, hypomagnesaemia, C. difficile risk).
When bacterial community-acquired pneumonia is diagnosed
- Amoxicillin 500 mg orally three times daily for 5 days
- If penicillin allergy: doxycycline 200 mg on day 1 then 100 mg once daily to complete 5 days
Antibiotic stewardship is essential; reassess if no improvement; use local antimicrobial guidance and severity tools (e. g, CRB-65).
Surgical / Interventional
- Emergency needle decompression followed by chest drain for tension pneumothorax
- Intercostal chest drain for significant non-tension pneumothorax when indicated
- Rigid/flexible bronchoscopy for suspected foreign body aspiration
- No routine surgical role for uncomplicated acute viral cough
Complications
- Cough syncope
- Sleep disturbance and fatigue
- Stress urinary incontinence (especially in women with chronic cough)
- Dysphonia
- Anxiety, low mood, frustration, and social isolation
- Reduced quality of life and relationship strain
Prognosis
Most acute coughs are self-limiting and improve within 3-4 weeks. Subacute post-infectious cough often resolves gradually, but chronic cough frequently has multifactorial causes and may relapse unless each driver (e. g, smoking, upper airway disease, asthma/eosinophilic inflammation, reflux, ACE inhibitor use) is addressed. Prognosis worsens when red-flag pathology (malignancy, PE, ILD, TB, heart failure) is missed or treatment is delayed.
Sources & References
💊BNF Drug References(2)
- Citric acid[management.pharmacological]
- Clarithromycin[management.pharmacological]
✅NICE Guidelines(1)
- Cough[overview]
📖Textbook References(5)
- David Randall PhD MRCP (Editor), John Booth PhD MRCP (Editor), K - Kumar and Clark's Clinical Medicine (2025, American Elsevier Publishing Co.) - libgen.li.pdf(pp. 1784)[context]
- David Randall PhD MRCP (Editor), John Booth PhD MRCP (Editor), K - Kumar and Clark's Clinical Medicine (2025, American Elsevier Publishing Co.) - libgen.li.pdf(pp. 579, 580)[context]
- David Randall PhD MRCP (Editor), John Booth PhD MRCP (Editor), K - Kumar and Clark's Clinical Medicine (2025, American Elsevier Publishing Co.) - libgen.li.pdf(pp. 569, 570)[context]
- Oxford Handbook of Clinical Diagnosis (Huw Llewelyn, Hock Aun Ang, Keir Lewis etc.) (Z-Library).pdf(pp. 189, 190)[context]
- Oxford Handbook of Clinical Diagnosis (Huw Llewelyn, Hock Aun Ang, Keir Lewis etc.) (Z-Library).pdf(pp. 189, 190)[context]