Upper Respiratory Tract Infection-Associated Acute Cough and the Urge to Cough: New Insights for Clinical Practice

Abstract

Upper respiratory tract infection (URTI)-associated acute cough is the most common symptom both in children and adults worldwide and causes economic and social problems with significant implications for the patient, the patient's family, and the health care system. New pathogenic mechanisms in acute cough, including the urge to cough (UTC) mechanisms, have been recently identified. The brainstem neural network, pharyngeal sensory innervation, airway mechanical stimulation, inflammatory mediators, and postnasal drip actively participate in the onset and maintenance of acute cough and the urge to cough phenomenon. However, there is still no effective pharmacological treatment capable of interfering with the pathophysiologic mechanisms involved in URTI-associated acute cough. Moreover, severe adverse events frequently occur in administering such cough medications, mainly in children. New evidence has been provided concerning polysaccharides, resins, and honey as potential cough relievers with high antitussive efficiency, effect on the UTC, and minimal side effects.

Keywords: acute cough; children; honey; pathophysiology; polysaccharides; treatment; upper respiratory tract infection; urge-to-cough.

FIG. 1.

The reflex of the cough.

FIG. 2.

The spectrum of the cough.

FIG. 3.

(A, B) The spectrum of the cough during URTI. (A) Urge to cough elicited by URTIs is probably situated in the intermediate area of the spectrum, mediated by the sense of irritation generated by mechanical and irritative stimuli caused by mucus, inflammatory mediators, and dryness. Oropharyngeal irritative sensory inputs travel to the brain cortex that elicits the urge to cough and actual cough. The urge to cough and cough may be initiated and inhibited by voluntary control from areas in the cerebral cortex. However, nearly two-thirds of the subjects with the urge to cough during common cold seem to be unable to control cough. That is what makes cough during URTIs so bothersome and long-lasting (image by Keller et al., modified). (B) The spectrum of cough during URTIs modulated by application of complex mixtures of natural substances on the pharynx. Polysaccharides and flavonoids exert a mechanical barrier effect, in addition to a demulcent effect, and indirect inflammatory activity that decrease the urge to cough and support the patient's ability to inhibit cough by voluntary control (Image by Keller et al., modified). URTI, upper respiratory tract infection.