Acute Cough

Acute cough is cough lasting less than 3 weeks. It is one of the commonest reasons for consultation in primary care, with most episodes being self-limiting viral respiratory tract infection (the common cold, acute bronchitis, influenza, COVID-19, parainfluenza, respiratory syncytial virus).

• The cough reflex protects the airway through vagal afferents (from the larynx, trachea, bronchi and, less often, the ear, oesophagus and stomach), a brainstem cough centre, and the respiratory muscles. A forceful expiration clears secretions and inhaled material.
• Common causes:
  • Viral upper and lower respiratory tract infection (about 80 to 90% of cases).
  • Acute bacterial bronchitis, pneumonia, pertussis (whooping cough), mycoplasma and chlamydial infection.
  • Exacerbation of asthma and chronic obstructive pulmonary disease.
  • Aspiration or inhalation of a foreign body, smoke, fumes or irritants.
  • Allergic rhinitis, postnasal drip, and acute sinusitis.
  • Heart failure, pulmonary embolism, pneumothorax and lung cancer (presenting acutely).
  • Medicines: angiotensin converting enzyme inhibitors (cough in 5 to 20% of patients, which can start days to months after beginning treatment).
• Acute bronchitis usually follows a viral illness, with a cough for 1 to 3 weeks (average 18 days), and about 25% still coughing at 4 weeks. The patient usually expects an antibiotic, but antibiotics add little and are not routinely needed.
• Risk factors for a complicated course: age above 65, smoking, chronic lung disease, heart disease, diabetes, immunosuppression, pregnancy, residential care.

• A dry or productive cough, often with nasal symptoms, sore throat, hoarseness, headache, fever and myalgia. Sputum colour (white, yellow or green) reflects inflammatory cells and does not reliably indicate bacterial infection.
• Acute bronchitis: retrosternal soreness, wheeze, sputum, and mild fever, with normal vital signs and no focal chest signs (coarse crackles or wheeze may be present).
• Pneumonia: fever above 38 C, respiratory rate above 24 breaths per minute, heart rate above 100 per minute, pleuritic chest pain, breathlessness, focal crackles or bronchial breathing, and confusion in older adults.
• Pertussis: paroxysmal cough with whoop, post-tussive vomiting and apnoea (in infants), lasting 6 to 12 weeks, and without fever.
• Asthma or COPD exacerbation: wheeze, breathlessness, chest tightness, and an increased inhaler need.
• Foreign body: abrupt onset of cough or choking, especially in young children and those with a swallowing disorder, with unilateral wheeze or reduced air entry.
• Heart failure or pulmonary embolism: breathlessness, orthopnoea, oedema, pleuritic pain, haemoptysis, and risk factors for thrombosis.
• Differential diagnosis: pneumonia, tuberculosis, lung cancer, pulmonary embolism, pneumothorax, heart failure, pulmonary oedema, aspiration, gastro oesophageal reflux, ACE inhibitor cough, pertussis, whooping-cough-like illness, laryngeal disease and vocal cord dysfunction.
• Red flags: haemoptysis, breathlessness at rest, respiratory rate above 30 breaths per minute, oxygen saturation below 92%, confusion, hypotension, stridor, chest pain, weight loss, night sweats, a history of cancer, immunosuppression, and age above 65 with fever.
• Complications: pneumonia, respiratory failure, rib fracture and chest wall pain, urinary incontinence, syncope, pneumothorax, subconjunctival haemorrhage, sleep loss and persistent cough beyond 3 weeks.

• Clinical. Record onset, duration, sputum, exposure to sick contacts and travel, smoking, medicines (especially ACE inhibitors), occupation, and pertussis or tuberculosis contact.
• Examine: temperature, pulse, respiratory rate, oxygen saturation on room air, blood pressure and mental state, with chest, ear, nose and throat examination.
• Pulse oximetry in all patients with breathlessness or suspected pneumonia. Measure peak expiratory flow when asthma is suspected.
• A chest X-ray is not required for a typical self-limiting acute cough with normal vital signs and examination. Perform it when pneumonia is suspected (abnormal vital signs, focal chest signs, age above 65 with fever), when red flags are present, or when symptoms persist beyond 3 weeks.
• For suspected pneumonia in primary care, use a severity score: confusion, urea above 7 mmol/L, respiratory rate 30 or more, low blood pressure (systolic below 90 or diastolic 60 or less) and age 65 or older (one point each). A score of 0 or 1 permits home treatment, 2 needs hospital assessment, and 3 or more suggests severe pneumonia.
• C-reactive protein point-of-care testing helps decide on antibiotics: below 20 mg/L makes pneumonia unlikely (no antibiotic), 20 to 100 mg/L suggests a delayed antibiotic strategy, and above 100 mg/L suggests antibiotics are indicated.
• Pertussis: nasopharyngeal swab for polymerase chain reaction within 3 weeks of onset, with serology later in the course. Treat on clinical suspicion, without waiting for results.
• Test for influenza and COVID-19 in appropriate settings. Sputum culture and sputum acid fast bacilli or a molecular test for tuberculosis (Xpert) when cough lasts more than 2 weeks with risk factors or weight loss.
• D-dimer, ECG and further tests for suspected pulmonary embolism or cardiac cause. B-type natriuretic peptide for suspected heart failure.

• Reassure that most coughs are viral and settle in 1 to 3 weeks (up to 4 weeks for acute bronchitis). Give safety netting advice: return if breathless, coughing blood, high fever, chest pain, worsening after initial improvement, or no improvement after 3 weeks.
• Supportive care:
  • Drink fluids to avoid dehydration, and rest. Humidified air and steam have little evidence of benefit, and hot water carries a risk of scalds.
  • Stop smoking and avoid irritants.
  • Honey: 2.5 mL (half a teaspoon) for children aged 1 to 5 years, 5 mL (one teaspoon) for 6 to 11 years, and 10 mL (two teaspoons) for 12 years and over, taken at bedtime or as needed. Do not give to infants under 1 year because of botulism risk.
• Symptomatic therapy (limited evidence, short courses):
  • Dextromethorphan 10 to 20 mg orally every 4 to 6 hours, or 30 mg every 6 to 8 hours (maximum 120 mg per day) for dry cough at night, for up to 5 to 7 days. Avoid with monoamine oxidase inhibitors and serotonergic antidepressants. Not recommended in children under 6 years.
  • Simple linctus or a lozenge for a dry irritating cough.
  • Guaifenesin 200 to 400 mg orally every 4 hours (maximum 2.4 g per day) as an expectorant, with limited evidence.
  • Paracetamol 1 g orally 6 hourly (maximum 4 g per day), or ibuprofen 400 mg orally 8 hourly with food, for fever and pain.
  • Avoid codeine and other opioid cough suppressants in children under 12 years, in pregnancy and in breastfeeding, and in respiratory depression.
  • Avoid over-the-counter cough and cold products in children under 6 years.
• Antibiotics are not indicated for acute bronchitis with normal vital signs, regardless of sputum colour. Consider them only for pneumonia, pertussis, an exacerbation of COPD with purulent sputum and breathlessness, or a patient at high risk (age above 65 with comorbidity, immunosuppression, cystic fibrosis).
• Community acquired pneumonia (mild, low severity score):
  • Amoxicillin 500 mg to 1 g orally 8 hourly for 5 days (child 1 month to 11 years 25 to 50 mg/kg 8 hourly, maximum 1 g per dose).
  • Penicillin allergy: doxycycline 200 mg orally on day 1, then 100 mg once daily for 4 days (children over 8 years), or clarithromycin 500 mg orally 12 hourly for 5 days.
  • Add clarithromycin 500 mg orally 12 hourly for 5 days when atypical pathogens are suspected.
  • Moderate to severe (score 2 or more): admit, with IV co-amoxiclav 1.2 g 8 hourly plus clarithromycin 500 mg 12 hourly, adjusted by local resistance patterns.
  • Review at 48 hours, and arrange a chest X-ray at 6 weeks in smokers and patients over 50 years to confirm resolution.
• Pertussis:
  • Azithromycin 500 mg orally once on day 1, then 250 mg once daily on days 2 to 5 (child 10 mg/kg once daily for 5 days). Or clarithromycin 500 mg orally 12 hourly for 7 days (child 7.5 mg/kg 12 hourly). Or co-trimoxazole 960 mg 12 hourly for 14 days when macrolides are contraindicated (not in the first 2 months of life).
  • Treatment within 3 weeks of onset reduces transmission, and has little effect on the cough itself. Offer prophylaxis to household contacts, especially infants, pregnant women in the third trimester, and immunocompromised patients.
  • Admit infants under 6 months and any patient with apnoea, cyanosis or feeding difficulty.
• Influenza: oseltamivir 75 mg orally 12 hourly for 5 days (child by weight) within 48 hours of onset in those at high risk or severely ill.
• COVID-19 and other viral diagnoses: supportive care, and consider antiviral therapy for patients at high risk when available.
• Asthma or COPD exacerbation: salbutamol 100 micrograms (2 to 4 puffs via spacer, repeat up to 10 puffs as needed), and prednisolone 30 to 40 mg orally once daily for 5 days (child 1 to 2 mg/kg, maximum 40 mg). Add antibiotics for COPD only when sputum is purulent and breathlessness has increased.
• ACE inhibitor cough: stop the ACE inhibitor and replace it with an angiotensin receptor blocker (for example losartan 50 mg once daily). The cough usually settles in 1 to 4 weeks, and up to 3 months in some patients.
• Foreign body suspicion: urgent paediatric or ENT referral for bronchoscopy.
• Special groups:
  • Children: oral rehydration, honey (over 1 year), nasal saline, and early review for fever, fast breathing (above 60 per minute for infants under 2 months, above 50 for 2 to 11 months, above 40 for 1 to 5 years), chest indrawing, stridor or poor feeding.
  • Pregnancy: paracetamol, honey, saline and steam inhalation. Amoxicillin and cefalexin are safe, and doxycycline is avoided. Azithromycin and erythromycin are options for atypical infections. Give influenza treatment.
  • Elderly: lower threshold for chest X-ray and admission, because pneumonia can present with confusion and no fever.
  • Immunosuppressed: low threshold for investigation and early antibiotics. Consider tuberculosis, Pneumocystis jirovecii and fungal infection.
  • Renal impairment: adjust doses of antibiotics (for example amoxicillin and co-trimoxazole), and avoid NSAIDs.
  • Hepatic impairment: reduce paracetamol to a maximum of 2 g per day.
• Follow up: review in 48 hours if there is concern about pneumonia. If cough persists beyond 3 weeks, arrange a chest X-ray and further assessment. Refer to a chest physician for haemoptysis, suspected cancer or tuberculosis, a persistent abnormal X-ray, or recurrent pneumonia.