Patients complaining of a persistent cough that lasts for >3 weeks after suffering the acute symptoms of an upper respiratory tract infection might have a post-infectious cough. These patients are considered to have a subacute cough as the condition mostly lasts for no >8 weeks. Chest radiograph findings are normal, ruling out pneumonia, and the cough eventually resolves on its own. The objective of this review is to evaluate the evidence for the diagnosis and treatment of post-infectious cough. This includes the most virulent form which is caused by Bordetella pertussis infection.

The search was restricted to human studies only by using the search terms "cough," "post-infectious cough," "Bordetella pertussis," "postviral cough," "pertussis infection," and "whooping cough."

The pathogenesis of the post-infectious cough is unknown; however, it is assumed to be due to the widespread inflammation and disruption of upper and lower airway epithelial integrity. When the post-infectious cough arises from the lower airway, this is frequently associated with the build-up of an excessive amount of mucus hyper-secretion or transient airway and cough receptor hyper-responsiveness. All these might contribute to the subacute cough. In such patients, the optimal treatment is also not known. Excluding bacterial sinusitis or early B pertussis infection, treatment with antibiotics has no role because the cause is not bacterial infection.

The use of inhaled ipratropium could be helpful. The other known causes of post-infectious cough are persistent inflammation of the nose and paranasal sinuses. These can lead to an upper airway cough syndrome (earlier it was referred as postnasal drip syndrome), and gastroesophageal reflux disease, which could be a complication of the forceful coughing. Another type of post-infectious cough is particularly virulent caused by B pertussis infection.

The diagnosis of a B pertussis infection should be made if another diagnosis is proven, when the cough is with paroxysms of coughing, post-tussive vomiting, or an inspiratory whooping sound. The B pertussis infection is highly contagious but it responds to antibiotic treatment with an oral macrolide when administered in the early course of the disease. A safe and an effective vaccine is now available for adults and children to prevent B pertussis. It is also recommended as per the CDC guidelines.

The review concluded that in patients having a cough that is lasting from 3 - 8 weeks with normal chest radiograph findings, consider the diagnosis of post-infectious cough. In most patients, a specific cause won’t be identified, and empiric treatment would be helpful. High degree of suspicion for cough because of B pertussis infection might help in earlier diagnosis, patient isolation as well as antibiotic treatment.

Source: Braman SS. Postinfectious cough: ACCP evidence-based clinical practice guidelines. Chest. 2006 Jan;129(1 Suppl):138S-146S. doi: 10.1378/chest.129.1_suppl.138S. PMID: 16428703.