Why a persistent cough may be more than just a cold

The Hindu

a day ago

A lingering cough is often dismissed as a minor inconvenience or a symptom that will clear up on its own. But when it persists for weeks, it can signal a more complex underlying issue. Pulmonologists and ENT specialists call for greater awareness around chronic cough -- not merely as a post-infection remnant, but as a potential marker of deeper respiratory or systemic concerns.
The prevalence of chronic cough in India varies across studies, but generally falls within the range of 5-10% of the adult population. This makes it a common symptom, particularly among those seeking primary care. While some studies suggest a prevalence of less than 5%, others show a higher range of 2% to 18%
When duration becomes a diagnostic clue
Doctors classify cough based on its duration into three main types. Acute cough lasts less than three weeks, subacute falls between three to eight weeks, and chronic cough refers to any that continues beyond eight weeks. But beyond time, the cause -- whether infectious or non-infectious -- shapes clinical understanding.
Acute cough is usually the result of viral upper respiratory tract infections or bacterial pneumonia. In the elderly or those with heart conditions, even bronchitis can be complicated by heart failure. Subacute cough often follows a resolved infection and may point to post-viral bronchitis. Chronic cough, however, opens up a broader diagnostic window, requiring evaluation for conditions like asthma, GERD (gastroesophageal reflux disease), chronic bronchitis, postnasal drip, COPD, or in more serious cases, pulmonary tuberculosis.
According to Shachi Dave, consultant pulmonologist at Narayana Hospital, Ahmedabad, 'If a cough lasts less than three weeks, it is usually benign. But if it continues beyond that-- especially with warning signs like fever, weight loss, coloured sputum, or blood -- it's vital to get it assessed by a physician.'
Symptoms like sore throat and fever typically point toward an upper respiratory tract infection in the early stages. If these fade but the cough persists, post-viral inflammation may be the cause. A night-time cough with nasal symptoms may indicate postnasal drip. Persistent reflux symptoms such as burning in the chest could signal GERD as the underlying issue. The nature of the cough -- dry, mucous-filled, or purulent -- also helps guide diagnosis.
The often-missed diagnosis of chronic cough
Misdiagnosis is common, with some studies showing that up to 60 percent of chronic cough cases are either mislabelled or inadequately treated. Frequently missed conditions include silent reflux, cough-variant asthma, eosinophilic bronchitis, and even obstructive sleep apnea.
'We often see patients labelled as allergic or asthmatic without adequate workup. Any cough that isn't resolving with primary care after a month should be evaluated by a pulmonologist,' says Ammaiyappan Palaniswamy, senior consultant at MGM Malar Hospital in Chennai.
Karthik Madesh Ratnavelu, ENT specialist at SIMS Hospital, adds that habit coughs, especially in children, and psychogenic coughs related to stress are often overlooked. In his view, early referrals and multidisciplinary approaches help avoid delayed diagnosis.
When the nerves are too sensitive
A significant body of research now recognises that many chronic coughs are driven not just by physical irritants, but by nerve hypersensitivity. This mechanism, much like that seen in chronic pain, involves both peripheral and central sensitisation of the nervous system.
Peripheral sensitisation occurs when airway receptors -- triggered by infections, allergens, or acid reflux -- become overly reactive. 'These receptors, once sensitised, begin responding strongly to even minor irritants,' explains Dr. Dave. Central sensitisation follows repeated stimulation, where the brainstem and higher centres of the brain become hyperexcitable, lowering the threshold for triggering a cough. As a result, stimuli like speaking, cold air, or even laughing can provoke coughing.
ATP, a chemical released during inflammation, plays a critical role by activating purinergic receptors like P2X3 on the vagus nerve, further enhancing this sensitivity. This understanding marks a shift in viewing chronic cough not just as a symptom, but sometimes as a disorder in itself.
Invisible triggers in everyday environments
Beyond infections and reflux, environmental triggers can also sustain or aggravate chronic cough. Common caused include hidden mold on walls, poorly ventilated homes or office spaces and exposure to scented products like air fresheners, incense and perfumes. Even the use of mosquito coils or chemical-based hair dyes has been implicated.
'Dust mites in bedsheets, furry blankets, or upholstery can set off coughing in allergic or asthmatic patients,' says Dr. Dave. 'Overcrowded living conditions and lack of sunlight or airflow also create ideal settings for infection spread, including tuberculosis.'
Lifestyle patterns also play a role. Skipping meals or relying heavily on outside food can increase gastric reflux. Stress, irregular sleep, dehydration, and overuse of the voice are other under-recognised contributors. Dr. Karthik warns that those in vocally demanding jobs -- teachers, speakers, and singers -- often present with coughs rooted in vocal strain rather than infection.
Making living and working spaces more cough-friendly
The idea of a 'cough-friendly' environment may seem abstract, but experts say small interventions can make a big difference. These include improving air circulation, maintaining moderate humidity, using air purifiers and reducing the use of strong-smelling products.
According to Pankaj Chhabra, clinical director at Marengo Asia Hospitals in Faridabad, 'Creating awareness is key. Homes, schools, and offices can all benefit from scent-free policies, periodic ventilation, and attention to allergens. It's more feasible than people think.'
He also emphasises hydration and vocal rest, particularly for those with existing airway sensitivity. Public understanding can reduce the stigma associated with chronic coughing -- especially post the worst phases of Covid-19 pandemic -- where a persistent cough carry social discomfort as well as physical toll.
Therefore, experts emphasis that a cough that persists for more than three weeks -- especially if accompanied by other symptoms like fever, night sweats, hoarseness, or weight loss -- should not be ignored. Early evaluation can help identify treatable conditions and prevent unnecessary suffering.
Chronic cough is not just an irritant. It's a clinical clue that deserves careful attention. Recognising its nuances, triggers, and neural underpinnings can pave the way for better outcomes and healthier indoor environments.