Definition¹

Cough in children may arise from causes anywhere along the airway, from the nose to the alveoli. Cough is a nonspecific reaction to irritation anywhere from the pharynx to the lungs. Childhood coughing is a common problem that can cause anxiety in parents. There are important differences from adult cough in terms of likely causes and management guidelines.

Chronic cough in children is generally defined as a cough lasting longer than eight weeks. This timeframe is used because most simple infective causes of cough will resolve in 3-4 weeks, and the eight-week definition identifies those who may need further investigations.

The timeframe between acute and chronic cough (3-8 weeks) is sometimes called 'subacute cough' or 'prolonged acute cough' (e.g. a slowly resolving post-viral cough). If a cough is starting to resolve after three weeks, further time may be allowed before investigating further. However, if the cough is not improving by the third week or is increasing in severity, earlier investigations may be indicated.

Epidemiology

Surveys show that parent-reported cough (as an isolated symptom) is common.¹

Aetiology¹

There is a wide range of possible causes. Awareness of 'red flag' symptoms is important (see 'Presentation', below).¹

Common causes in primary care

• Infections (or recurrent infections) - including respiratory syncytial virus (RSV), adenovirus, Mycoplasma pneumoniae, chlamydial pneumonia, whooping cough (pertussis) and tuberculosis.
• Asthma.
• Postnasal drip syndrome.
• Environmental agents - tobacco smoke, possibly charcoal or kerosene heaters.
• Gastro-oesophageal reflux.

Less common causes

• Inhaled foreign body.
• Cystic fibrosis.
• Immune deficiency.
• Congenital lesions, e.g. tracheo-oesophageal fistula, tracheomalacia.
• Ciliary dyskinesia.
• Neurological, e.g. tics,² psychogenic cough. Psychogenic cough may be bizarre, honking and decrease with sleep or attention to other activities.
• For a full list of other causes, see the British Thoracic Society's (BTS) guidelines.¹

Pointers to particular causes of chronic cough

Onset:

• Neonatal onset of cough - consider congenital malformations, aspiration, lung infections, cystic fibrosis.
• Very acute onset - inhaled foreign body.

• Child well, no other symptoms - consider nonspecific isolated cough, recurrent viral bronchitis, psychogenic cough, habit cough (dry repetitive cough which disappears with sleep).
• Systemic ill health or recurrent pneumonia - consider tuberculosis, inhaled foreign body, cystic fibrosis, immune disorders, persistent bronchitis, recurrent aspiration.

• Associated with wheezing or breathlessness - consider asthma, inhaled foreign body, recurrent pulmonary aspiration, cardiac disease, airways compression, tracheobronchomalacia, bronchiolitis.
• Associated shortness of breath and restrictive lung defect - interstitial lung disease.
• Cough occurs in paroxysmal spasms with an inspiratory 'whoop' - whooping cough.
• Cough is brassy, croupy or bizarre and honking - consider tracheal or glottic irritation and psychogenic causes.
• 'Wet' or productive cough (most young children do not expectorate sputum but tend to swallow it) - consider bronchiectasis or any suppurative lung condition, e.g. cystic fibrosis.
• Relentlessly progressive cough - consider inhaled foreign body, lobar collapse, tuberculosis, rapidly expanding intrathoracic lesion.
• True haemoptysis (apparent haemoptysis may be related to nose bleeds, cheek biting or haematemesis) - consider pneumonia, lung abscess, bronchiectasis, retained inhaled foreign body, tuberculosis, pulmonary hypertension.
• Triggers:
  • Exercise/excitement/cold air/nocturnal cough/change in environment, e.g. pets - consider asthma.
  • Swallowing/meals - recurrent aspiration.
  • Lying down - postnasal drip, gastro-oesophageal reflux.
  • Attention - psychogenic.
  • Angiotensin-converting enzyme (ACE) medication - ACE inhibitor-induced cough.
• Mannerisms associated with unusual stereotypical coughs - suggest Tourette's syndrome (although the diagnosis of Tourette's syndrome cannot be made on a single tic, including isolated cough).

Presentation

Make an initial assessment, looking for pointers towards a specific cause, and for any 'red flags' (see box).

History¹

• Nature of cough:
  • The sound - e.g. brassy or seal-like (suggests tracheal/glottic irritation); bizarre or honking (suggests psychogenic).
  • Wet or dry (productive or not) - NB: young children don't expectorate sputum but may vomit it.
  • Haemoptysis or sputum.
• Onset, duration, time course of cough.
• Triggers.
• Does the cough disappear when sleeping?
• Other symptoms - including fever, weight loss, night sweats.
• Family history - especially atopy or respiratory disease.
• Medication.
• Cigarette smoke exposure or other environmental pollutants, e.g. heating fuel.

Examination

• General features - fever, height/weight and any failure to thrive, clubbing, lymphadenopathy, signs of atopy.
• Upper airway - abnormal voice or crying, inspiratory stridor, ENT examination.
• Respiratory signs - dyspnoea, respiratory rate, chest auscultation.
• Observation of the cough if possible.

Investigations

Which children need investigating in primary care?³

Belgian primary care guidelines suggest the following strategy:

• 'Red flags' present - require specific investigations depending on the clinical picture.
• No 'red flags':
  • If fever - exclude pneumonia.
  • For immigrants - exclude tuberculosis.
  • If there are pointers to a specific cause - investigate appropriately (e.g. spirometry, serology, oesophageal pH monitoring).
  • If there are no specific pointers - consider CXR.

Which investigations?¹

BTS guidelines suggest the following strategy when investigating chronic cough:

Initial investigations:

• CXR.
• Spirometry (or peak flow monitoring in older children³) ± tests of bronchodilator responsiveness or bronchial hyper-reactivity.

Further investigations:

• Obtain a sputum sample if possible - for microbiology and cytology.
• Allergy testing (skin prick or radioallergosorbent test (RAST) specific testing) may help if atopy/asthma are likely diagnoses.
• Other tests will depend on the clinical picture and differential diagnosis.

Trial of treatment:¹

• BTS guidelines suggest that in contrast with adults, for children with a dry cough who are well and have no specific disease pointers, empirical trials of treatment (for asthma, allergic rhinitis or gastro-oesophageal reflux) are unlikely to be beneficial and are generally not recommended.
• However, in young children, BTS suggests that, as it may be difficult to rule out asthma as a cause of coughing in young children, a trial of anti-asthma therapy may be used (e.g. inhaled corticosteroids). Ensure effective delivery, adequate doses and clear recording of outcomes.
• Set a time (e.g. 8-12 weeks) after which the trial of anti-asthma medication should be stopped. If the child has responded to anti-asthma therapy and the treatment has subsequently been stopped, an early relapse that again responds to treatment is suggestive of cough-variant asthma. If there is no response, asthma is unlikely.

Differential diagnosis

It is important to differentiate between a nonspecific, isolated, dry cough in an otherwise well child, and a child who is unwell or has 'red flag' symptoms and signs (see box, above).

Management

• This depends on any specific cause found.
• In a well child with no 'red flags', aim to avoid invasive investigations and to explore the expectations and anxieties of parents.
• Remove environmental contributions if possible, e.g. tobacco smoke.
• Antitussive drugs, other than simple cough linctus, are not generally recommended.³

Document references

1. Recommendations for the assessment and management of cough in children, British Thoracic Society (Sept 2007)
2. Tan H, Buyukavci M, Arik A; Tourette's syndrome manifests as chronic persistent cough. Yonsei Med J. 2004 Feb 29;45(1):145-9. [abstract]
3. Leconte S, Paulus D, Degryse J; Prolonged cough in children: a summary of the Belgian primary care clinical Prim Care Respir J. 2008 Dec;17(4):206-11. [abstract]