Cough — Frequently asked questions (FAQ)
1) What does this algorithm cover?
The algorithm guides the diagnostic assessment of cough in adults and adolescents, organising the evaluation according to the duration of symptoms—acute, subacute or chronic cough. It includes the identification of severity criteria, features suggestive of structural disease or malignancy, the main differential diagnoses, and guidance on complementary tests and further investigation.
2) How is cough classified according to its duration?
Cough is generally classified as:
acute (< 3 weeks),
subacute (3–8 weeks), and
chronic (> 8 weeks).
This classification helps identify the most likely diagnoses and determine the need for further investigation.
3) Which severity criteria require urgent assessment?
Urgent assessment is warranted in the presence of significant breathlessness, hypoxaemia, severe chest pain, haemoptysis, altered mental status, hypotension, suspected severe pneumonia, a severe asthma exacerbation or signs of airway obstruction. These findings may indicate potentially serious disease and the need for urgent referral.
4) When should lung cancer be suspected?
Suspicion should increase in patients over 40 years of age, with a significant smoking history, a recent change in the cough pattern, unexplained weight loss, persistent hoarseness, supraclavicular lymphadenopathy, progressive breathlessness or a previous history of malignancy. In these cases, a priority chest X-ray and possible chest CT should be considered.
5) What is the most common cause of acute cough?
Most cases are caused by viral upper respiratory tract infections, including nasopharyngitis, influenza, COVID-19 or acute tracheobronchitis. In the absence of severity criteria, treatment is generally symptomatic and antibiotics are not required.
6) What characterises a post-infectious cough?
Post-infectious cough typically develops after an acute respiratory infection and may persist for several weeks. There is usually progressive clinical improvement, with no systemic features or relevant abnormalities on physical examination. In most cases, it resolves spontaneously with monitoring and symptomatic treatment.
7) What are the main causes of chronic cough?
The main causes include upper airway cough syndrome (UACS), asthma, non-asthmatic eosinophilic bronchitis, gastro-oesophageal reflux disease (GORD), smoking and cough induced by ACE inhibitors. The algorithm helps guide investigation and targeted empirical treatment.
8) Which complementary tests should be performed?
For chronic cough, a chest X-ray and spirometry with bronchodilator testing are generally recommended. Additional tests—such as chest CT, bronchoscopy, oesophageal pH monitoring or cardiac investigation—should be reserved for selected cases, lack of response to treatment or suspected structural disease.
9) Can ACE inhibitors cause cough?
Yes. Angiotensin-converting enzyme inhibitors (ACE inhibitors) are a common cause of dry chronic cough. The cough may develop weeks or months after treatment is started and tends to improve after the medicine is discontinued, although complete resolution may take several weeks.
10) When should further investigation be considered?
Further investigation should be considered when there is no response to targeted treatment, prolonged persistence of the cough, abnormal initial test results or the presence of red flags. Depending on the clinical context, this may include chest CT, bronchoscopy, ENT assessment, cardiac investigation or gastroenterological evaluation.
11) What is the role of empirical treatment?
In the absence of severity criteria, a targeted empirical approach to the most common causes of chronic cough may be appropriate, such as antihistamines and intranasal corticosteroids for UACS, bronchodilators and inhaled corticosteroids for asthma, or proton pump inhibitors for GORD. Clinical response should be reassessed after 4–6 weeks.
