Clinical Guides
Approach to Cough
A clinically focused clinical approach to acute and chronic cough in adults, integrating urgent triage, tuberculosis case-finding, targeted respiratory investigation, treatment limits and the realities of Indian referral and diagnostic access.
MedNext Academy | 13 min read
Approach to Cough
A clinically focused clinical approach to acute and chronic cough in adults, integrating urgent triage, tuberculosis case-finding, targeted respiratory investigation, treatment limits and the realities of Indian referral and diagnostic access.
Summary
Cough is a protective respiratory reflex and a symptom rather than a diagnosis. The first task is to decide whether the patient is physiologically unstable or has a time-critical cause such as severe pneumonia, pulmonary embolism, acute heart failure, major haemoptysis, airway compromise or tuberculosis with public-health implications. Once immediate danger is excluded, duration helps organise reasoning: acute cough usually lasts less than three weeks, subacute cough three to eight weeks, and chronic cough more than eight weeks in adults. These intervals guide probability but must never override severity, trajectory or context.
A focused assessment asks what the cough sounds and feels like, when it began, whether it is dry or productive, and what accompanies it. Fever, breathlessness, chest pain, wheeze, haemoptysis, weight loss, aspiration, exposure to tuberculosis, smoking, occupational dust, medicines and immune status change the differential. Examination includes respiratory rate, oxygen saturation, work of breathing, haemodynamic state, chest findings and relevant cardiac, ear-nose-throat and systemic signs.
Most uncomplicated acute coughs are viral and improve without antibiotics. Chronic cough requires a structured rather than indiscriminate work-up: chest radiography and spirometry are core tests, with full blood count and fractional exhaled nitric oxide where available, followed by tests directed by findings. Asthma or eosinophilic airway disease, smoking-related disease, upper-airway symptoms, reflux, an ACE-inhibitor effect and cough hypersensitivity are common considerations, but tuberculosis must remain visible in India. Safety-netting is part of management, not an afterthought.
How Common Is It?
Cough is among the commonest reasons for ambulatory clinical contact, but a single prevalence figure is misleading because surveys use different durations, age groups and definitions. Acute cough clusters with viral respiratory infections and seasonal exposures. Chronic cough is less common, disproportionately affects middle-aged women in specialist cohorts, and can cause urinary leakage, sleep disruption, rib pain, voice change, social embarrassment and impaired work. The burden is therefore greater than a symptom count suggests.
Population frequency does not identify the cause in an individual. In primary care, a short cough without red flags is often self-limited infection. In a respiratory clinic, referral selection increases the proportion of asthma, eosinophilic bronchitis, reflux-associated symptoms, bronchiectasis and cough hypersensitivity. In people who smoke or have substantial biomass exposure, chronic bronchitis and chronic obstructive pulmonary disease become more likely. In a child, the differential, duration thresholds and safeguarding issues differ, so this adult guide should not be applied mechanically.
India adds a high-consequence tuberculosis background and major variation in air quality, household smoke, occupational exposure and access to radiography or spirometry. National or global TB estimates describe programme burden, not the probability that any single cough represents tuberculosis. Conversely, the frequency of viral cough must not be used to dismiss prolonged symptoms, haemoptysis, weight loss, fever, night sweats or a relevant contact. Pre-test probability should be recalculated at every review when symptoms persist or evolve.
Risk Factors
Risk assessment should be cause-specific. For severe acute infection, consider older age, frailty, pregnancy, cardiopulmonary disease, chronic kidney or liver disease, diabetes, immunosuppression and recent hospital care. Aspiration risk rises with impaired consciousness, dysphagia, neurological disease, vomiting and poor airway protection. Venous thromboembolism risk, recent surgery, immobility, malignancy and oestrogen exposure matter when cough accompanies unexplained dyspnoea or pleuritic pain.
For tuberculosis, ask about household or close contact, previous TB treatment, residence or work in congregate settings, undernutrition, HIV, diabetes, smoking, silicosis, immunosuppressive therapy and barriers that delay care. These factors modify suspicion; none alone diagnoses or excludes disease. Lung cancer risk rises with age, tobacco exposure, radon or occupational carcinogens and previous malignancy. Bronchiectasis is more likely after recurrent infections, childhood lung disease, tuberculosis, immune deficiency or chronic daily purulent sputum.
Chronic cough can be promoted by active or passive smoking, vaping, biomass fuel, traffic pollution and workplace irritants. Asthma may be associated with atopy, variable wheeze, nocturnal symptoms and triggers, yet cough can be its dominant symptom. Angiotensin-converting-enzyme inhibitors cause cough independently of dose or timing and can remain responsible even after long exposure. Reflux symptoms, rhinitis, obesity and obstructive sleep apnoea may coexist, but association is not proof of causation. A careful exposure and medicine timeline often produces more value than a broad unselected test panel.
Diagnosis
History
Record duration, onset, progression, bouts, triggers, nocturnal pattern, sputum volume or blood, fever, breathlessness, wheeze, chest pain, choking, nasal symptoms, heartburn, voice change and systemic features. Ask about TB contact, previous TB, smoking or vaping, biomass and occupational exposure, travel, infection contacts, vaccination, immune status and current medicines, especially an ACE inhibitor. Clarify whether the patient means coughing blood, vomiting blood or nasopharyngeal bleeding. Explore sleep, continence, work and psychological impact without implying that unexplained cough is imaginary.
Examination
Measure temperature, pulse, blood pressure, respiratory rate and oxygen saturation, and assess speech, mental state, cyanosis and work of breathing. Look for cachexia, pallor, clubbing, lymph nodes and signs of dehydration. Examine the nose, pharynx and voice when relevant. Chest examination should note focal crackles, bronchial breathing, wheeze, stridor, asymmetry and signs of effusion. Assess cardiac failure, calf asymmetry and aspiration risk when suggested. A normal examination does not exclude asthma, tuberculosis, pulmonary embolism or early malignancy.
Investigations
Uncomplicated acute cough may need no test. Obtain chest radiography for chronic cough and earlier when pneumonia, TB, malignancy, heart failure or another structural process is suspected. Chronic assessment generally includes spirometry with bronchodilator testing, full blood count, and FeNO where available. Tuberculosis evaluation uses appropriate respiratory sampling and a WHO-recommended rapid molecular test within the NTEP pathway; smear microscopy alone is less informative for resistance. Further CT, cultures, eosinophil assessment, ECG, cardiac testing, bronchoscopy or specialist tests must answer a defined question. A normal chest radiograph does not end evaluation when red flags persist.
Differential Diagnosis
For acute cough, common viral upper-respiratory infection and acute bronchitis sit alongside pneumonia, asthma exacerbation, COPD exacerbation, COVID-19 or influenza according to circulation, and aspiration. Do not miss pulmonary embolism, pneumothorax, acute pulmonary oedema, anaphylaxis, foreign body or epiglottic and upper-airway obstruction. Pleuritic pain, hypoxaemia, haemodynamic change, unilateral signs or a disproportionate respiratory rate should pull reasoning away from a routine infection label.
A subacute cough may be post-infectious, including after pertussis, but it may also be an evolving presentation of asthma, tuberculosis or another chronic disorder. Chronic cough is approached through identifiable disease and treatable traits. Possibilities include asthma, non-asthmatic eosinophilic bronchitis, COPD, bronchiectasis, tuberculosis, interstitial lung disease, lung cancer and chronic infection. Upper-airway disease may produce rhinitis, congestion or throat clearing. Reflux can contribute when typical symptoms or a convincing temporal relation exists, but empiric acid suppression is not a universal diagnostic test. ACE-inhibitor cough can occur without a close start-date relation.
If imaging and spirometry are normal and targeted trials fail, consider cough hypersensitivity, inducible laryngeal obstruction and less common airway or neurological causes. Habitual throat clearing and heightened laryngeal sensation are real phenomena, not permission to stop assessing danger. Cardiac failure, dysphagia with microaspiration and medicine effects should remain in the cross-system differential. In children, persistent wet cough, congenital lesions and foreign body have different pathways and require paediatric guidance.
Management
Stabilise emergencies first: provide supportive resuscitation within competence, isolate or use infection-control precautions when airborne disease is plausible, and arrange urgent transfer for respiratory compromise, major haemoptysis or another time-critical diagnosis. For an uncomplicated acute viral cough, explain the expected course, hydration and simple symptom measures, and give an explicit return plan. Antibiotics offer little benefit for most acute coughs and should not be prescribed because sputum is coloured. Consider them only when bacterial infection is clinically supported or the patient is systemically very unwell or at high complication risk, using local antimicrobial guidance.
Management of chronic cough should follow demonstrated disease or a testable trait. Support smoking cessation and reduce avoidable occupational, household or pollution exposure. Review an ACE inhibitor with the prescriber and substitute an appropriate alternative when clinically safe; improvement can take weeks. Use objective testing and guideline-based inhaled treatment for asthma or eosinophilic disease rather than indefinite unmonitored trials. Treat rhinitis when upper-airway inflammation is evident. Reserve reflux therapy for patients with compatible symptoms or evidence; lifestyle measures and weight management may be relevant, but acid suppression often fails when heartburn is absent.
Tuberculosis testing and treatment belong in the NTEP pathway with rapid diagnostics, drug-susceptibility information, notification, contact evaluation and adherence support. Persistent unexplained cough after core tests and targeted treatment warrants respiratory referral. Specialist cough-control therapy and selected neuromodulators may help refractory cough, but adverse effects and limited evidence demand supervision and shared decisions.
Prescribing Information
No medicine should be prescribed simply to suppress a cough before its cause and danger have been considered. For acute self-limited illness, medicine benefit is modest. Avoid routine antibiotics, and do not use sputum colour as a bacterial marker. Where pneumonia or another bacterial infection is established, select an agent, dose and duration from current local antimicrobial policy, allergies, renal and hepatic function, pregnancy status, recent antibiotics and microbiology. Tuberculosis must never be treated with an improvised single antibiotic or incomplete regimen; treatment is programme-based and requires resistance-aware combination therapy.
Bronchodilators and inhaled corticosteroids are not general cough remedies. They are appropriate when asthma, COPD or eosinophilic airway disease is supported and must include device selection, inhaler-technique teaching, adherence review and an outcome checkpoint. Inhaled corticosteroids can cause dysphonia and oral candidiasis; high exposure adds systemic risk. Oral corticosteroids carry hyperglycaemia, infection and other harms and should not substitute for diagnostic work.
If an ACE inhibitor is suspected, coordinate substitution rather than abruptly removing cardiovascular or renal protection without a plan. Empiric proton-pump inhibitors should not be continued indefinitely when there is no typical reflux or response. Sedating antihistamines, codeine-containing mixtures and other antitussives can impair driving, worsen constipation or cause dependence; product age restrictions and interactions matter. Specialist neuromodulators for refractory cough require discussion of sedation, dizziness and uncertain long-term benefit. Pregnancy, lactation, childhood and frailty require separate verification against an approved formulary.
When to Refer
Arrange emergency assessment for severe respiratory distress, stridor, inability to speak normally, cyanosis, altered consciousness, shock, rapidly falling oxygen saturation, suspected anaphylaxis, large or ongoing haemoptysis, tension pneumothorax, pulmonary embolism with instability or acute pulmonary oedema. The receiving service and transport level should match physiological risk. Do not send an unstable patient to routine radiology or outpatient clinic without support.
Refer urgently through a suspected-cancer or equivalent rapid pathway when cough is accompanied by concerning imaging, persistent haemoptysis, a neck or supraclavicular mass, unexplained weight loss or a high-risk clinical pattern. Suspected pulmonary tuberculosis requires prompt NTEP-linked diagnostic evaluation and infection-control advice; urgency rises with severe disease, HIV, pregnancy, young household contacts or drug-resistance risk. Recurrent pneumonia, persistent focal signs, significant hypoxaemia, unexplained clubbing or a foreign-body history also merit expedited specialist assessment.
For chronic cough, refer when the chest radiograph is abnormal, spirometry shows significant disease, the diagnosis remains uncertain, or cough continues despite removal of obvious triggers and properly conducted targeted trials. BTS guidance supports secondary-care review for chronic cough with a normal radiograph that does not respond to treatment. Refer earlier for immunosuppression, previous cancer, occupational disease, complex bronchiectasis, interstitial lung disease or disabling cough-related syncope. Ear-nose-throat, speech and language, gastroenterology or cardiology input should be chosen for a defined clinical question, not used as serial exclusion by default.
Red Flags
Red flags begin with physiology: respiratory rate rising, oxygen saturation low or falling, exhaustion, silent chest, stridor, cyanosis, altered mental state, hypotension and inability to maintain hydration require immediate escalation. Sudden pleuritic pain, unilateral absent breath sounds, new hypoxaemia or syncope suggests pneumothorax or pulmonary embolism. Frothy sputum with orthopnoea and widespread crackles may reflect pulmonary oedema. Choking onset raises foreign-body or aspiration concern. A normal temperature does not make these presentations safe.
Haemoptysis must be quantified and distinguished from other bleeding. Large-volume, recurrent or physiologically significant bleeding is an emergency; even small recurrent haemoptysis needs timely investigation. Persistent fever, night sweats, weight loss, loss of appetite, TB exposure or previous TB should trigger rapid tuberculosis assessment, especially with HIV, diabetes or immunosuppression. Persistent hoarseness, clubbing, focal chest signs, supraclavicular nodes or an abnormal radiograph raise concern for malignancy or structural lung disease.
Additional warning patterns include cough lasting beyond the expected acute course with deterioration, repeated presentations, recurrent pneumonia in one lobe, aspiration symptoms, immunosuppression and new cough in a person with cancer. Severe coughing can itself cause syncope, rib fracture, vomiting or urinary incontinence; syncope while driving or operating machinery creates immediate safety risk. Safety-net instructions should specify which symptoms require emergency care, which require same-day review and when persistence alone should prompt reassessment, with a route the patient can realistically access.
Indian Clinical Context
In India, tuberculosis must be actively considered without turning every cough into a TB diagnosis. Prolonged cough, fever, night sweats, weight loss, haemoptysis, contact, previous TB or high-risk immune status should lead to NTEP-linked evaluation. WHO's 2025 diagnostic guidance supports rapid molecular assays as initial tests in appropriate people; the exact locally available platform and sampling pathway vary. A negative result reduces probability but may not exclude paucibacillary or extrapulmonary disease, so discordant clinical and radiographic findings need review. Notification, resistance testing, contact evaluation and treatment support are programme responsibilities, not optional extras.
Primary-care access to pulse oximetry and chest radiography is broader than access to quality-assured spirometry, FeNO, CT or bronchoscopy. A safe plan can therefore be staged: triage danger, obtain the highest-yield available test, initiate indicated infection control, and define where and when unavailable testing will occur. Biomass smoke, tobacco, construction or mining dust, traffic pollution and poorly ventilated work may be central to the history. Advice should be feasible and should not blame patients who cannot immediately change housing or employment.
Antibiotic overuse for undifferentiated cough drives harm and resistance. Public and private clinicians should document the indication, review point and stop date rather than issuing repeated short courses. Multilingual counselling, cost, travel, wage loss and stigma affect TB testing and follow-up. The NTEP helpline and local programme contacts may support navigation, but availability should be verified. Imported UK referral rules inform principles; they are not Indian legal or service protocols.
NMC Competency Mapping
This symptom approach integrates NMC respiratory-medicine, infectious-disease, pharmacology, microbiology, community-medicine and communication outcomes. A learner should explain the cough reflex, classify cough by duration without treating cutoffs as diagnoses, construct an acute and chronic differential, and recognise respiratory failure, major haemoptysis, pneumothorax, pulmonary embolism and severe airway obstruction. Respiratory examination must be linked to respiratory rate, oxygenation and functional severity rather than a recital of auscultatory signs.
Tuberculosis learning should include risk assessment, respiratory sampling, interpretation of rapid molecular testing, basic drug-resistance implications, airborne infection control, notification and the NTEP care pathway. For obstructive airway disease, the learner should obtain exposure and variability histories, perform supervised peak-flow or spirometry technique, interpret obstruction and bronchodilator response, and demonstrate inhaler teaching. Pharmacology integration includes antibiotic stewardship, adverse effects of corticosteroids and sedating antitussives, and safe review of an ACE inhibitor.
Competence can be assessed through a station in which the candidate first identifies instability, then presents a prioritised differential and a proportionate investigation plan. A second station can test counselling for a person referred for TB testing without stigma or false reassurance. Exact institutional competency codes should be checked against the authorised NMC 2024 ledger rather than guessed from older summaries. Reading this draft does not certify independent diagnosis, prescribing, spirometry quality assurance or management of a respiratory emergency, and it does not indicate completed organizational clinical review.
Key Exam Pearls for NEET PG
Acute, subacute and chronic cough are conventionally separated at three and eight weeks, but an emergency diagnosis is determined by physiology and associated features, not duration. A barking cough or stridor suggests an upper-airway process; a paroxysmal cough with post-tussive vomiting suggests pertussis; daily large-volume purulent sputum suggests bronchiectasis. Asthma may present with cough and normal examination between episodes. COPD requires persistent airflow obstruction in an appropriate exposure context, not smoking history alone.
ACE-inhibitor cough is typically dry and can begin long after treatment starts; resolution after withdrawal may take several weeks. Upper-airway disease and reflux can coexist with cough, but empiric treatment without a matching trait is weak reasoning. A normal radiograph does not exclude asthma, early tuberculosis, pulmonary embolism or endobronchial disease. Chronic cough core assessment includes chest radiography and spirometry, with full blood count and FeNO where available. CT is not the automatic first test after every normal radiograph.
Coloured sputum alone does not establish bacterial infection, and most uncomplicated acute bronchitis does not benefit from antibiotics. Haemoptysis plus weight loss, persistent fever, TB exposure, clubbing or focal signs changes urgency. In India, suspected pulmonary TB should enter a rapid molecular diagnostic pathway with resistance information rather than rely on an empiric fluoroquinolone course. In an examination stem, first stabilise a hypoxaemic or shocked patient, isolate when airborne infection is plausible, and then investigate. The highest-scoring answer is often the one that names both the likely cause and the dangerous alternative that must be excluded.
Frequently Asked Questions
How long can an uncomplicated acute cough reasonably last before it needs reassessment?
Many viral coughs improve over two to three weeks, and some persist longer, but duration is only one safety signal. Reassessment is needed sooner for breathlessness, chest pain, haemoptysis, fever with deterioration, low oxygen saturation, weight loss, TB exposure or other red flags. A cough that is not following the expected trajectory should not receive repeated blind antibiotic courses.
Does green or yellow sputum mean that an antibiotic is required?
No. Sputum colour reflects inflammatory cells and does not by itself distinguish viral from bacterial infection. Antibiotic decisions should use the complete presentation, physiological severity, pneumonia evidence, comorbidity, microbiology when indicated and current local guidance. Systemically very unwell or high-risk patients require clinical review rather than colour-based prescribing.
When should tuberculosis be considered in a patient presenting with cough in India?
Consider TB when cough is prolonged or accompanied by fever, night sweats, weight loss, haemoptysis, a relevant contact, previous TB, abnormal imaging or vulnerability such as HIV, diabetes or immunosuppression. Suspicion should lead to an NTEP-linked rapid diagnostic pathway and infection-control advice. No single symptom duration or negative screening question safely excludes TB.
What are the minimum useful tests for an adult with otherwise unexplained chronic cough?
A chest radiograph and quality-assured spirometry are core tests; a full blood count and FeNO are also recommended where available. Further testing should follow history, examination and those results. Persistent cough despite a normal radiograph and targeted treatment deserves specialist assessment, because normal initial tests do not exclude every important airway or structural cause.
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