Acute cough is commonly defined as a cough that lasts less than 21 days (3 weeks). The average duration is 18 days, although it can sometimes last for up to 29 days (over 4 weeks). It is most commonly caused by an upper respiratory tract infection, such as a cold or flu, which are viral infections. It can also be caused by acute bronchitis, a lower respiratory tract infection, which is usually a viral infection but can be bacterial.
Other infective causes of cough include COVID-19, pneumonia, acute exacerbations of asthma, chronic obstructive pulmonary disease or bronchiectasis (which may also be non-infective exacerbations), and viral-induced wheeze, bronchiolitis, croup or whooping cough. Non-infective causes may include lung cancer, a foreign body, interstitial lung disease, pneumothorax, pulmonary embolism, heart failure, use of certain medicines (for example, an angiotensin-converting enzyme inhibitor), upper airway cough syndrome (post-nasal drip), or gastro-oesophageal reflux disease. (NICE clinical knowledge summaries on cough, chest infections – adult, cough – acute with chest signs in children and Ebell et al. 2013).
Acute bronchitis is a lower respiratory tract infection with temporary inflammation of the airways (the trachea and major bronchi) that causes cough and mucus production lasting for up to 3 weeks. It is usually caused by a viral infection, but may be caused by a bacterial infection. (NICE clinical knowledge summary on chest infections – adult).