Persistent cough

Coughs are often benign or self-limiting but can present a dilemma of how best to manage. A precise diagnosis can often be difficult and empirical treatment may be prescribed where a precise diagnosis cannot be made.

Carcinoma (red) is one of the many possible causes of persistent cough
Carcinoma (red) is one of the many possible causes of persistent cough

But with TB and whooping cough both reported to be on the increase in the UK, it is important to know what to look out for when presented with a persistent cough.

In 2006, a study in the BMJ highlighted that 37 per cent of school-age children with cough lasting [s40]14 days had serological evidence of a Bordetella pertussis infection. Most of the children in the study were fully immunised.

Aside from a respiratory tract infection, asthma and cystic fibrosis are possible diagnoses in children with persistent cough. Inhaled foreign bodies should be considered, particularly in children.

Signs and symptoms
In adults, a persistent cough coupled with any of the red flag symptoms should prompt further investigation. Neoplastic disease, pulmonary embolism, pulmonary oedema, asthma and COPD are all serious underlying conditions that may present with a cough.

Have a lower threshold for arranging a chest X-ray in middle-aged and elderly smokers, especially if the patient has experienced unexplained weight loss or noticed a change in voice.

Early detection and diagnosis are crucial when managing lung cancer. The NICE guidelines for lung cancer recommend immediate referral for patients with swelling of both the face and neck caused by an obstruction in the jugular veins, or stridor.

Urgent referral is recommended for patients with persistent haemoptysis who are smokers or ex-smokers aged 40 years and older.

A robust medication and travel history should be taken. The contraceptive Pill increases the risk of pulmonary embolism whereas ACE inhibitors may cause cough by elevating pulmonary bradykinin levels.

Atypical pneumonia or TB should be considered in travellers or immunocompromised patients.

Possible causes

  • Lung cancer
  • Pulmonary embolism
  • Pulmonary oedema
  • Cystic fibrosis
  • Asthma
  • COPD
  • GORD
  • Post-nasal drip
  • Allergy

Resources

  • NICE guidance on COPD, lung cancer and TB.

Reference

  • BMJ 2006; 333: 174-7.

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