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Last updated: April 21, 2020


A cough is a forceful expulsion of air from the lungs that helps to clear secretions, foreign bodies, and irritants from the airway. It may be classified as acute (< 3 weeks), subacute (3–8 weeks), or chronic (> 8 weeks), as well as productive (with sputum/mucus expectoration) or dry. Upper respiratory tract infections (URI) and acute bronchitis are the most common causes of acute cough. Subacute cough is often a sequela of a URI (postinfectious cough) but can also be due to chronic bronchitis or pneumonia. Chronic cough is often caused by rhinitis/sinusitis (upper airway cough syndrome), asthma, GERD, and ACE inhibitors. A thorough medical history and physical examination often suffice to diagnose the etiology of cough. Chronic cough or the presence of associated red flag symptoms (dyspnea, fever, hemoptysis, weight loss) are indications for further investigation. Sputum culture, chest x-ray/CT scan, and pulmonary function tests are useful diagnostic tests in the evaluation of cough, but are not routinely indicated. Treatment of cough depends on the underlying etiology.


  • Definition: a forceful expulsion of air from the lungs that helps to clear secretions, foreign bodies, and irritants from the airway
  • May be voluntary or a reflex to airway irritants/triggers
  • Cough reflex arc
    1. Irritation of cough receptors in the nose, sinuses, and upper and lower respiratory tracts (see the triggers above)
    2. Transmission along the afferent pathway via the vagus nerve (CN X) to the cough center in the medulla
    3. Generation of efferent signal in the medulla and initiation of cough via the vagus, phrenic, and spinal motor nerves
  • Mechanism of cough reflex
    • Irritation of cough receptors → initiation of the cough reflex arc, which leads to:
      • Rapid inspiration, closure of the epiglottis and vocal cords (which traps inhaled air in the lungs), and contraction of the diaphragm, expiratory, and abdominal muscles → rapid increase of intrathoracic pressure
      • A sudden opening of the vocal cords and forceful expulsion of air from the lungs




Differential diagnosis of acute cough

(< 3 weeks)

Non-life-threatening causes
Life-threatening causes
In children

Subacute cough

(3–8 weeks)

Differential diagnosis of chronic cough

In adults

(> 8 weeks)

In children

(> 4 weeks)




Clinical examination:



  • An acute cough is often a clinical diagnosis (diagnostic tests are not routinely indicated in this case).
  • Patients with chronic cough and/or red flag symptoms (see “Approach” above) require further assessment.

Laboratory tests


Pulmonary function tests


Close history taking and physical examination are sufficient to diagnose the cause of an acute cough without red flag symptoms! In chronic cough and cough with red flag symptoms, thoracic x-ray and pulmonary function testing should be considered at an early stageReferences:[12][17][18][19][20]


Acute cough

Subacute cough

Chronic cough

Symptomatic treatment of a cough

Antitussive medications decrease coughing, which is important for the expectoration of mucus! They are not usually indicated if an infection is the cause of cough.



  1. Walker HK, Hall WD, Hurst WJ, Silverman ME, Morrison G. Clinical Methods: The History, Physical, and Laboratory Examinations. Butterworths ; 1990
  2. Silvestri RC, Weinberger SE. Evaluation of Subacute and Chronic Cough in Adults. In: Post TW, ed. UpToDate. Waltham, MA: UpToDate. https://www.uptodate.com/contents/evaluation-of-subacute-and-chronic-cough-in-adults.Last updated: July 11, 2014. Accessed: May 22, 2017.
  3. Benich JJ, Carek PJ. Evaluation of the patient with chronic cough. Am Fam Physician. 2011; 84 (8): p.887-892.
  4. Mosenifar Z. Viral Pneumonia. In: Byrd RP, Viral Pneumonia. New York, NY: WebMD. http://emedicine.medscape.com/article/300455. Updated: July 11, 2016. Accessed: May 22, 2017.
  5. Kryger MH, Roth T, Dement WC. Principles and Practice of Sleep Medicine. Elsevier ; 2010
  6. Cough in Adults. https://www.msdmanuals.com/professional/pulmonary-disorders/symptoms-of-pulmonary-disorders/cough-in-adults. Updated: July 1, 2016. Accessed: May 22, 2017.
  7. Coughlin L. Cough: diagnosis and management. Am Fam Physician. 2007; 75 (4): p.567-575.
  8. Pratter MR. Chronic upper airway cough syndrome secondary to rhinosinus diseases (previously referred to as postnasal drip syndrome): ACCP evidence-based clinical practice guidelines. Chest. 2006; 129 (1 Suppl): p.63S-71S. doi: 10.1378/chest.129.1_suppl.63S . | Open in Read by QxMD
  9. Gorguner M, Akgun M. Acute inhalation injury. Eurasian J Med. 2010; 42 (1): p.28-35. doi: 10.5152/eajm.2010.09 . | Open in Read by QxMD
  10. Braman SS. Postinfectious cough: ACCP evidence-based clinical practice guidelines. Chest. 2006; 129 (1 Suppl): p.138S-146S. doi: 10.1378/chest.129.1_suppl.138S . | Open in Read by QxMD
  11. Le T, Bhushan V. First Aid for the USMLE Step 1 2015. McGraw-Hill Education ; 2014
  12. Tatar M, Hanacek J, Widdicombe J. The expiration reflex from the trachea and bronchi. Eur Respir J. 2008; 31 (2): p.385-390. doi: 10.1183/09031936.00063507 . | Open in Read by QxMD
  13. Spina D, Page CP, Metzger WJ, O'Connor BJ. Drugs for the Treatment of Respiratory Diseases. Cambridge University Press ; 2003
  14. Ternesten-Hasséus E, Larsson S, Millqvist E. Symptoms induced by environmental irritants and health-related quality of life in patients with chronic cough - A cross-sectional study. Cough. 2011; 7 : p.6. doi: 10.1186/1745-9974-7-6 . | Open in Read by QxMD
  15. Belvisi MG, Geppetti P. Cough. 7: Current and future drugs for the treatment of chronic cough. Thorax. 2004; 59 (5): p.438-440.
  16. Guyton AC. Textbook of Medical Physiology. Elsevier ; 2006
  17. George L, Brightling CE. Eosinophilic airway inflammation: role in asthma and chronic obstructive pulmonary disease. Ther Adv Chronic Dis. 2016; 7 (1): p.34-51. doi: 10.1177/2040622315609251 . | Open in Read by QxMD
  18. Priftis KN, Anthracopoulos MB, Eber E, Koumbourlis AC, Wood RE. Paediatric bronchoscopy. Prog Respir Res. 2010; 38 : p.30-41. doi: 10.1159/000314382 . | Open in Read by QxMD
  19. Bronchoalveolar Lavage. https://www.thoracic.org/professionals/clinical-resources/critical-care/clinical-education/critical-care-procedures/bronchoalveolar-lavage.php. Updated: May 1, 2004. Accessed: May 22, 2017.
  20. Islam S. Flexible Bronchoscopy in Adults: Indications and Contraindications. In: Post TW, ed. UpToDate. Waltham, MA: UpToDate. https://www.uptodate.com/contents/flexible-bronchoscopy-in-adults-indications-and-contraindications.Last updated: February 1, 2017. Accessed: May 22, 2017.
  21. Simon RH. Cystic Fibrosis: Overview of the Treatment of Lung Disease. In: Post TW, ed. UpToDate. Waltham, MA: UpToDate. https://www.uptodate.com/contents/cystic-fibrosis-overview-of-the-treatment-of-lung-disease.Last updated: February 13, 2017. Accessed: February 16, 2017.
  22. Weinberger SE, Silvestri RC. Treatment of Subacute and Chronic Cough in Adults. In: Post TW, ed. UpToDate. Waltham, MA: UpToDate. https://www.uptodate.com/contents/treatment-of-subacute-and-chronic-cough-in-adults.Last updated: March 29, 2016. Accessed: March 23, 2017.
  23. Irwin RS. Guidelines for treating adults with acute cough. Am Fam Physician. 2007; 75 (4): p.476-482.
  24. Cox N, Hinkle R. Infant botulism. Am Fam Physician. 2002; 65 (7): p.1388-1392.
  25. Van Amburgh JA. Do Cough Remedies Work?. Do Cough Remedies Work?. New York, NY: WebMD. http://www.medscape.com/viewarticle/803288. Updated: May 3, 2013. Accessed: May 22, 2017.
  26. Townley RG, Suliaman F. The mechanism of corticosteroids in treating asthma. Ann Allergy. 1987; 58 (1): p.1-6.
  27. Sylvester DC, Karkos PD, Vaughan C, et al. Chronic cough, reflux, postnasal drip syndrome, and the otolaryngologist. Int J Otolaryngol. 2012 . doi: 10.1155/2012/564852 . | Open in Read by QxMD
  28. Vaezi MF. Atypical manifestations of gastroesophageal reflux disease. MedGenMed. 2005; 7 (4): p.25.
  29. Badillo R, Francis D. Diagnosis and treatment of gastroesophageal reflux disease. World J Gastrointest Pharmacol Ther. 2014; 5 (3): p.105-112. doi: 10.4292/wjgpt.v5.i3.105 . | Open in Read by QxMD
  30. Chest Physiotherapy. http://www.msdmanuals.com/professional/pulmonary-disorders/pulmonary-rehabilitation/chest-physiotherapy. Updated: March 1, 2017. Accessed: May 22, 2017.
  31. Padma L. Current drugs for the treatment of dry cough. J Assoc Physicians India. 2013; 61 (5 Suppl): p.9-13.
  32. Herold G. Internal Medicine. Herold G ; 2014