Cough is one of the most common complaints presenting to any emergency physician or primary care practitioner – whether it is the chief complaint or an associated symptom. An acute cough is one that has been present for less than three weeks. In the era of COVID-19, a patient presenting with an acute cough can be alarming and scary. So, now more than ever, it is important to develop a strong diagnostic approach to the acute cough, which is largely a clinical diagnosis.
Differential Diagnosis of Acute Cough*Indicates the most common causes of acute cough.
|Cause||Example||Symptoms / warning signs|
|Infectious (viral/bacterial)||Upper respiratory tract infection aka common cold*||Rhinorrhea, nasal obstruction, sneezing, scratchy/sore throat, malaise, headache, and no signs of consolidation|
|Acute bronchitis*||Recent upper respiratory tract infection, and absence of COPD, and absence of high fever or other systemic signs|
|Influenza||Fever, sore throat, nasal congestion, myalgia, headache, and no signs of consolidation|
|Pneumonia*||Fever, tachycardia, tachypnea, consolidation signs on respiratory exam, and mental status change in patients >75y old|
|Pertussis||Whooping cough and cough-emesis|
|COVID-19||Fever, non-productive cough, fatigue, dyspnea, and/or other less common symptoms such as sore throat, diarrhea, headache, skin rash, and anosmia|
|Post-nasal drip aka upper airway cough syndrome||Post-nasal drainage sensation, need to clear throat, and rhinorrhea|
|Allergic rhinitis aka hay fever||Itching and watering of eyes, rhinorrhea, pruritis|
|Exacerbation of a pre-existing chronic disease||Exacerbation of Asthma||History of episodic wheezing, non-productive cough, dyspnea, reversible air-flow obstruction, allergen exposure or triggered by exercise|
|Exacerbation of COPD||Smoking history, dyspnea, signs of obstruction on respiratory exam i.e. decreased breath sounds, and irreversible air-flow obstruction|
|Exacerbation of CHF||Dyspnea, orthopnea, peripheral edema, gallop rhythm on cardiac exam, and elevated JVP|
|Drug-induced||ACE inhibitor use||Non-productive cough, tickling or scratchy sensation in throat typically arising within 1 week of starting medication|
reflux disorder (GERD)
|Heartburn, regurgitation, dysphagia, and cough is more prominent at night|
|Other pulmonary causes||Pulmonary embolism||Clinical signs and symptoms of DVT, dyspnea, tachypnea, tachycardia, pleuritic chest pain, immobilization for 3 or more days, surgery in the past 4 weeks, history of DVT/PE, hemoptysis, and malignancy with active treatment in the past 6 months|
|Lung cancer||Smoking history, new change in cough, hemoptysis, dyspnea, night sweats, weight loss, and signs of focal obstruction on respiratory exam i.e. decreased breath sounds|
|Foreign body aspiration||Dyspnea, inspiratory stridor, choking, and elevated risk in children|
|Acute inhalation injury||History of exposure to smoke (e.g. in firefighters, thermal burn victims) or chemicals (e.g. chlorine, ammonia)|
|Bronchiectasis||Large volumes of purulent sputum, dyspnea, wheezing, and chest pain|
|Interstitial lung disease||Non-productive cough, dyspnea, fatigue, weight loss|
Picture the scene: A 23-year-old female presents to the emergency department with a cough that has been ongoing for one week. What are your next steps?
- Confirm the duration and timing of cough
- Nature of cough, i.e. whooping, hemoptysis, and productive vs non-productive?
- Presence of the following associated symptoms: fever, dyspnea, sore throat, headache, chest pain, heartburn, rhinorrhea, facial pressure/pain, nasal congestion, or weight loss
- History of any chronic lung disease (i.e. asthma, COPD), allergies, CHF, or immunosuppression?
- Smoking history?
- Medication history, i.e. ACE inhibitor use?
- HEENT exam (head, eyes, ears, nose, and throat)
- Respiratory exam
- Cardiac exam, including JVP
- Send for COVID-19 swab according to your hospital’s guidelines
- Order CBC if suspecting infection
- Order ABG if dyspnea present or life-threatening cause of acute cough suspected
- Order sputum culture if suspecting bacterial pneumonia
- Spirometry if need to differentiate between obstructive lung disease (e.g., asthma, COPD) and restrictive lung disease (e.g., interstitial lung disease)
- Consider starting with a Chest X-ray if red flags for serious pathology are present >> dyspnea, hemoptysis, chest pain, weight loss, immunosuppression, significant smoking history, elderly or at risk of aspiration, tachypnea or hypoxemia, abnormal cardiac or respiratory exam, or sepsis.
- If suspecting foreign body aspiration, need to order bronchoscopy
Please note that treatment of the conditions that may cause acute cough are not discussed in this blog post, but can be found through medical resources such as those in the references section. Treatment for acute cough often requires treating the underlying cause.
- Boujaoude ZC, Pratter MR. Clinical approach to acute cough. Lung. 2010;188 Suppl 1(Suppl 1):S41-S46. doi:10.1007/s00408-009-9170-6
- Holzinger F, Beck S, Dini L, Stöter C, Heintze C. The diagnosis and treatment of acute cough in adults. Dtsch Arztebl Int. 2014;111(20):356-363. doi:10.3238/arztebl.2014.0356
- Madison JM, Irwin RS. Cough: A worldwide problem. Otolarynogol Clin North Am. 2010 Feb;43(1):1-13, vii.
- Strong Medicine. An Approach to Cough. Published 25 March, 2018. https://www.youtube.com/watch?v=LDMEtNXik-A
- University of Toronto. Cough and Dyspnea. 2015. http://thehub.utoronto.ca/family/cough-and-dyspnea/ Accessed 17 August, 2020.