Cough suppression as a radical but effective therapeutic strategy

Lady Windermere gave cough suppression a bad name. Being born into polite society she famously declined to cough resulting in lung disease with mucus plugging and bronchiectasis. Radical as the idea may seem, it may be time to revisit the belief that cough suppression is always bad and that it is essential to always ‘get the stuff out’ to quote the sentiment expressed by many of my patients. Cough is a natural protective response to achieve lung clearance of noxious inhaled material, especially particulates. It is also essential to clear excess mucus production associated with various pathologies to promote tissue healing and to prevent infection. However, there are several situations where cough suppression could be invaluable if applied, albeit without strong research evidence to support this idea—as yet Source: Freepik (Xiongwu, AI generated). In a general population the commonest reason for cough is virus infections. Viruses are highly effective pathogens and their success is due to an ability to make the human host cough early, often and for as long as possible to ensure spread to other potential hosts. The stimulus for cough is airway inflammation and a degree of hyperresponsiveness induced by the virus infection. There are seldom airway secretions to be cleared but that may sometimes be needed later if secondary bacterial infection complicates the picture. Given that sputum clearance is a low priority during the initial infection and there is no benefit to the host organism, why not consider cough suppression as a stratagem in this circumstance? Cough suppression as a therapeutic strategy can have persuasive advantages. First, virus infections are extremely common, and if cough suppression is successful curbing spread of infection will have a large overall community benefit on absenteeism and productivity. Next, although virus infections are omnipresent and impossible to fully eliminate, more gradual dissemination through the community can reduce pathogenicity with smooth development of herd immunity necessary to curtail and stop most virus infections at a community level. Finally, a key advantage could be to restrict prolonged airway hyperresponsiveness in many people, particularly if they have asthma or an allergic background. It may just avert bothersome post-viral cough. Is there a scientific rationale for cough suppression? Recent research has demonstrated that cough has both forward (afferent) and backward (efferent) feedback loops that are processed through brainstem pathways. Once activated the loops can become self-perpetuating leading to ongoing cough for weeks, months and rarely life-long as ‘chronic cough’. The irritating effects of cough also prolong airway hyperresponsiveness keeping the forward cough loop active. Interruption of a vicious circle of cough—and more cough—by disregarding cough impulses could help to mitigate this very common, and troublesome scenario. It may be particularly efficacious at early stages of virus infection before hyperresponsiveness and a ‘doom loop’ of cough becomes established. The biggest obstacle to this radical (but arguably rational) idea will be the almost universal belief in society that any stimulus to cough must be obeyed. This stems from the idea that cough is good since it ‘clears out the lung’, a collective societal conviction that can be difficult to counter. However, if people were to be convinced of the benefit of this strategy, most will be able to suppress cough, at least partially. At the level of community general practice encouraging people to try not to cough as a part of waiting for cold symptoms to subside can have few downsides and large overall societal, and personal, benefit. Imagine the considerable benefits to health if general practitioners told everyone with a cold to try to suppress cough—leading to reductions in viral spread and post-viral cough. Are there any potential dangers? Clearly uninfected sputum production does not need expectoration and cough can be consciously suppressed since lung macrophages and other innate mechanisms will clear mucus rapidly and effectively. Copious purulent sputum may require review, antibiotics and encouraging cough to treat secondary bacterial infections. Finally, evidence for efficacy may be difficult to obtain and for many researchers the idea may sound just too simple to be good and true. In the context of a ‘natural therapy’ so straightforward and ‘simple’, perhaps we should remember Isaac Newton who said: ‘Nature is pleased with simplicity’ and Leonardo da Vinci who added: ‘Simplicity is the ultimate sophistication’.