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Chronic cough
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In one pass Coughing is a protective reflex.
Educational content, not medical advice — consult a clinician.
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Chapter 1
Why a cough won't stop
Coughing is a protective reflex. Endings of the vagus nerve sit in the lining of the throat and windpipe; when something irritates them, they signal the brainstem, which orders a forceful breath out that blasts out foreign material and mucus. The reflex is there to protect you: people with a weak cough reflex are the ones who keep inhaling things into their lungs.
The trouble is that it can be turned up. By duration, a cough under 3 weeks is acute and usually a cold; 3 to 8 weeks is often the tail end of a cold; only beyond 8 weeks in adults (4 weeks in children) is it called chronic cough. In most people with chronic cough, a little cold air, perfume or smoke sets off a bout. It is not that something stays in the airway; the alarm threshold has dropped.
So when a cough has gone on for a long time, the question is what turned the reflex up, not how to keep pushing the cough down.
Coughing up blood or labored breathing: see a doctor soon. If you cough up a lot of blood, can't get your breath or have chest pain, go to the emergency department now.
The trouble is that it can be turned up. By duration, a cough under 3 weeks is acute and usually a cold; 3 to 8 weeks is often the tail end of a cold; only beyond 8 weeks in adults (4 weeks in children) is it called chronic cough. In most people with chronic cough, a little cold air, perfume or smoke sets off a bout. It is not that something stays in the airway; the alarm threshold has dropped.
So when a cough has gone on for a long time, the question is what turned the reflex up, not how to keep pushing the cough down.
Coughing up blood or labored breathing: see a doctor soon. If you cough up a lot of blood, can't get your breath or have chest pain, go to the emergency department now.
Mechanism · How a single cough happens
The vagal nerve endings in the airway lining carry several kinds of sensors (ion channels such as TRPV1, TRPA1 and P2X3). Fluid coming up from the stomach, acid, cigarette smoke, particles, and liquids that are too concentrated or too dilute can all trigger them. These nerves are generalists: the same ending responds to both chemical and mechanical stimuli. released by stressed cells is another important trigger.The signal travels up the vagus nerve to the brainstem, which then organizes a cough, and the cerebral cortex can turn the reflex up or down. The sensing areas are not only in the throat and windpipe: the depths of the lung, the throat, the esophagus and even the ear canal have vagal branches, which is why some people cough when they clean their ears.
The system has a lot of redundancy and plasticity: it adapts, and so it can be turned up. That is the foundation of chronic cough.
Numbers · How long is long, and how common
The American College of Chest Physicians (CHEST) sorts cough into three groups by duration, each with different common causes:Under 3 weeks: mostly viral respiratory infections, followed by flare-ups of asthma or , and pneumonia.3 to 8 weeks: most often a post-cold cough, followed by flare-ups of asthma or COPD and nasal problems.Over 8 weeks: problems of the nose and sinuses, asthma, gastroesophageal reflux, eosinophilic bronchitis without asthma, or several of these at once; less commonly, a range of other conditions and, in Asian countries, a type called atopic cough.
The studies behind this are all of low quality, but the scheme has held up on every continent.
A cited by the European Respiratory Society (ERS) 2020 guideline estimates that about 10% of adults worldwide have chronic cough. In specialist cough clinics, two-thirds of patients are women, and the most common age at presentation is the fifties.
Chapter 2
Still coughing after a cold
Still coughing a week or two after a cold is common. The cause is usually not that the virus is still there; the cold made the cough reflex more sensitive. In challenge tests with capsaicin (the irritant in chili peppers), a lower concentration sets off a cough during a cold, and it takes 4 to 8 weeks after the infection to return to where it was.
This post-cold cough comes with a normal chest X-ray, usually stops on its own, and generally lasts no more than 8 weeks. Antibiotics do not help, because it is not a bacterial infection; the exceptions are bacterial sinusitis and early whooping cough.
A few practical points:
For children over 1, honey may mean a little less coughing at night, with the benefit concentrated in the first three days. Do not give honey under age 1: it can carry the bacteria that cause botulism.Pharmacy cough suppressants and expectorants have trials that contradict each other; nobody can say whether they work.Bouts of coughing until you can't breathe, vomiting after coughing, or a whooping sound on breathing in should make you think of whooping cough (pertussis). It is highly contagious, adults get it too, and antibiotics help if started early: see a doctor.
This post-cold cough comes with a normal chest X-ray, usually stops on its own, and generally lasts no more than 8 weeks. Antibiotics do not help, because it is not a bacterial infection; the exceptions are bacterial sinusitis and early whooping cough.
A few practical points:
For children over 1, honey may mean a little less coughing at night, with the benefit concentrated in the first three days. Do not give honey under age 1: it can carry the bacteria that cause botulism.Pharmacy cough suppressants and expectorants have trials that contradict each other; nobody can say whether they work.Bouts of coughing until you can't breathe, vomiting after coughing, or a whooping sound on breathing in should make you think of whooping cough (pertussis). It is highly contagious, adults get it too, and antibiotics help if started early: see a doctor.
Mechanism · How a cold turns the cough up
A cold leaves more than a runny nose in the airway. Researchers have proposed several threads: more release of inflammatory signals, neurotransmitters and leukotrienes; more sensors on the nerve endings; lower activity of an enzyme that clears irritating small molecules (neutral endopeptidase); and too much mucus. The surface layer of the airway is also disrupted by the inflammation and takes time to heal.The result has two sides: a weaker stimulus is enough to trigger a cough, and the urge to cough you feel in your throat beforehand gets stronger too. Both usually return to normal within 4 to 8 weeks.
In a few people they don't. The idea of cough hypersensitivity offers an explanation: an ordinary cold can be the starting point of chronic refractory cough in some people. So a cough that has not stopped 8 weeks after a cold is no longer treated as the tail of the cold; it needs looking into.
Evidence · How much backs honey and cough syrups
Honey: a Cochrane systematic review pooled 6 randomized trials of 899 children aged 1 to 18. Compared with no treatment or placebo, honey probably reduces how often children cough (moderate certainty); it is about the same as dextromethorphan (a common cough-medicine ingredient), and may be a little better than diphenhydramine (low certainty). The benefit is concentrated in the first three days; beyond that no advantage shows. Most children took it for only one night, which is the weak point of this evidence, and the authors' own conclusion is that there is no strong evidence for or against it.Do not give honey to babies under 1: the US Centers for Disease Control and Prevention (CDC) warns that honey can contain the bacteria that cause botulism.
Over-the-counter cough medicines: another Cochrane review looked at 29 placebo-controlled trials in 4,835 people. Cough suppressants, expectorants, mucus thinners and antihistamine-decongestant combinations all gave conflicting results; there is no good evidence that they work, and no good evidence that they don't.
Chapter 3
A cough reflex set too sensitive
Chronic cough is now understood as cough hypersensitivity: the vagal nerve endings that raise the alarm fire too easily, so a little cold air, perfume, smoke or bleach sets off a bout. Many people describe a constant tickle or urge to cough in the throat; that is what a lowered threshold feels like.
What lowers the threshold is often something that can be found and treated:
The asthma family: about a quarter of people have airway inflammation involving eosinophils, including cough-variant asthma (cough with no wheeze) and eosinophilic bronchitis without asthma.Inflammation of the nose and sinuses.Reflux: not only stomach acid; gas and non-acid fluid coming up may also play a part, and among people with chronic cough, an esophagus that moves food poorly is common (see gerd).
Some people still have no cause after a full workup. Then the problem lies mainly in the nerves themselves; this is called chronic refractory cough, and it can be treated too.
What lowers the threshold is often something that can be found and treated:
The asthma family: about a quarter of people have airway inflammation involving eosinophils, including cough-variant asthma (cough with no wheeze) and eosinophilic bronchitis without asthma.Inflammation of the nose and sinuses.Reflux: not only stomach acid; gas and non-acid fluid coming up may also play a part, and among people with chronic cough, an esophagus that moves food poorly is common (see gerd).
Some people still have no cause after a full workup. Then the problem lies mainly in the nerves themselves; this is called chronic refractory cough, and it can be treated too.
Numbers · The usual causes of chronic cough in China
A multicenter study prospectively examined 704 adults with chronic cough in five regions of China and found a cause in 90.9%:Cough-variant asthma 32.6%Nose and sinus problems (upper airway cough syndrome) 18.6%Eosinophilic bronchitis 17.2%Atopic cough 13.2%Reflux-related cough only 4.6%
The first four together made up 75.2% to 87.6% in the different regions; season, sex and age did not change the picture.
What this means for you: in China, someone who has coughed for over two months should first be checked for the asthma family and the nose, not the stomach. It fits the point made in How a doctor tests and tries treatment: without heartburn, starting with acid-suppressing drugs is often the wrong door.
Clinical · More common in women, often with leaks
In specialist cough clinics, two-thirds of patients are women, most often in their fifties. The guideline links this to sex differences in how the brain processes the sensation of cough: in women, a larger area of the cerebral cortex is devoted to it.Coughing brings its own chain of complications. The ones that hit daily life hardest are stress urinary incontinence (leaking urine when you cough), trouble speaking and low mood. Women who leak when they cough have a clearly worse quality of life, yet few bring it up.
So if you leak urine when you cough, say so at the appointment: it shows how much the cough is affecting you, and it is a problem that needs dealing with in its own right.
Chapter 4
Two causes: a blood pressure drug, and smoking
Two causes are especially easy to overlook, and you can check both yourself first.
ACE inhibitor blood pressure drugs (names usually end in -pril) let bradykinin and other irritants build up in the airway, turning the cough reflex up. About 15% of people on these drugs develop a dry cough; individual studies report 5% to 35%. The cough can start within hours of the first tablet or only months later, which is why so many people never suspect it. After stopping, it usually eases within 1 to 4 weeks, sometimes lingering up to 3 months. Don't stop the drug yourself: take the box to your doctor and discuss switching to another class. Angiotensin receptor blockers (names ending in -sartan) do not affect the cough reflex (see hypertension).
Smoking is the major cause of chronic cough that can be removed. The counterintuitive part: nicotine in smoke suppresses the cough reflex, so in the first month after quitting, the cough may temporarily get worse. The guideline tells doctors to warn patients about this in advance: it does not mean quitting went wrong; keep going.
ACE inhibitor blood pressure drugs (names usually end in -pril) let bradykinin and other irritants build up in the airway, turning the cough reflex up. About 15% of people on these drugs develop a dry cough; individual studies report 5% to 35%. The cough can start within hours of the first tablet or only months later, which is why so many people never suspect it. After stopping, it usually eases within 1 to 4 weeks, sometimes lingering up to 3 months. Don't stop the drug yourself: take the box to your doctor and discuss switching to another class. Angiotensin receptor blockers (names ending in -sartan) do not affect the cough reflex (see hypertension).
Smoking is the major cause of chronic cough that can be removed. The counterintuitive part: nicotine in smoke suppresses the cough reflex, so in the first month after quitting, the cough may temporarily get worse. The guideline tells doctors to warn patients about this in advance: it does not mean quitting went wrong; keep going.
Mechanism · Why ACE inhibitors cause a cough
ACE (angiotensin-converting enzyme) has two jobs in the body. One is to cut angiotensin into the form that tightens blood vessels, which is what the drug is meant to block. The other is to break down bradykinin and substance P, two molecules that irritate airway nerves. When the drug blocks the enzyme, these two molecules build up in the upper airway and lungs and also drive production of prostaglandins, so the cough reflex is turned up. Angiotensin receptor blockers block the receiving end for angiotensin and leave this enzyme alone, so cough with them is about as common as with placebo.The guidelines stress two points:
Once the reflex has been reset, the cough often does not line up in time with starting or stopping the drug. So in anyone with chronic cough, an ACE inhibitor should be treated as a possible cause whether or not the timing fits.The only reliably effective fix is to stop this class of drug. A minority can take it again without the cough returning, but the guideline advises that someone who is already coughing should not be given an ACE inhibitor.
Safety · Other drugs that can add to a cough
Besides ACE inhibitors, the guideline names a few drugs that can add to a cough indirectly:Bisphosphonates (common osteoporosis drugs) and calcium channel blockers (a common class of blood pressure drug, names often ending in -dipine) may worsen existing reflux, and the cough with it.Prostaglandin eye drops (such as latanoprost for glaucoma) can run down the tear duct into the throat and irritate it.
Each of these drugs treats something real, so again, don't stop them yourself. Giving your doctor a list of everything you take, eye drops included, is the cheapest step in a chronic cough workup.
Chapter 5
How a doctor tests and tries treatment
The first step in a chronic cough workup is ruling things out: lung tumors, infection (tuberculosis included), something inhaled into the airway, and ACE inhibitor blood pressure drugs. The basic tests are lung function (spirometry) and a chest X-ray. When the X-ray and examination are normal, the guideline advises against routinely adding a chest CT; its radiation has to be weighed against what it might find.
After that, treatment is usually tried in sequence: one thing at a time. If it works, it continues for several months to let the oversensitive nerves settle, then stops to see whether the cough comes back; if it doesn't work, it stops and the next thing is tried. If the asthma family is suspected, for example, a 2- to 4-week trial of an inhaled steroid may come first.
A common mistake: for chronic cough without heartburn, don't take acid-suppressing drugs long term on your own. The guideline advises against routine use: in people without acid reflux, they do no better than placebo.
If the cough persists after all that, doctors have drugs that act directly on the nerves, such as low-dose morphine-type drugs or gabapentin. Their side effects need weighing, so a doctor prescribes and adjusts them.
After that, treatment is usually tried in sequence: one thing at a time. If it works, it continues for several months to let the oversensitive nerves settle, then stops to see whether the cough comes back; if it doesn't work, it stops and the next thing is tried. If the asthma family is suspected, for example, a 2- to 4-week trial of an inhaled steroid may come first.
A common mistake: for chronic cough without heartburn, don't take acid-suppressing drugs long term on your own. The guideline advises against routine use: in people without acid reflux, they do no better than placebo.
If the cough persists after all that, doctors have drugs that act directly on the nerves, such as low-dose morphine-type drugs or gabapentin. Their side effects need weighing, so a doctor prescribes and adjusts them.
Evidence · Inhaled steroids and acid drugs
The European Respiratory Society 2020 guideline gives a strength for each recommendation:Short trial of an inhaled steroid (2 to 4 weeks): conditional recommendation, low-quality evidence. Ten randomized trials gave mixed results: two found a benefit in unselected chronic cough patients, while in people without airway hyperresponsiveness it did no better than placebo.Short trial of a leukotriene receptor antagonist (such as montelukast): conditional recommendation, mainly for asthma-type cough.Acid-suppressing drugs (proton pump inhibitors and H2 blockers): a conditional recommendation not to use them routinely. In systematic reviews they did no better than placebo in people without acid reflux, and gave only a small benefit in those with it; one trial of 12 weeks at high dose in people with little or no heartburn found no improvement either.Low-dose slow-release morphine: for refractory cough, strong recommendation, moderate-quality evidence. Gabapentin or pregabalin: conditional recommendation, low-quality evidence; side effects such as dizziness and fatigue often limit them.
Doses and durations are set by a doctor, and the nerve-acting drugs are not used in children.
Chapter 6
Cough control you can learn
For people whose cough has no cause found, or who still cough after treatment, there is a drug-free approach that worked in randomized trials: cough control therapy, led by a speech and language therapist or a respiratory physiotherapist. You can learn what it teaches ahead of time:
Repeated dry coughing does the body no good; it only irritates the throat further, and coughing is something you can learn to control.Catch the signal before the cough: the moment your throat tickles and you're about to cough, meet it with a substitute action, such as a hard swallow, breathing out slowly through pursed lips, or relaxing your throat and breathing gently.Cut down irritation of the throat: drink enough to keep it moist, and avoid the smoke and smells that set you off.
In one trial of 87 people, 88% of those who had the training were judged to have succeeded, compared with 14% in the control group. In a multicenter trial, coughing fell 41% relative to the control group, and the effect lasted to 3 months. It takes a few sessions with an experienced therapist; reading about it once is not enough.
Repeated dry coughing does the body no good; it only irritates the throat further, and coughing is something you can learn to control.Catch the signal before the cough: the moment your throat tickles and you're about to cough, meet it with a substitute action, such as a hard swallow, breathing out slowly through pursed lips, or relaxing your throat and breathing gently.Cut down irritation of the throat: drink enough to keep it moist, and avoid the smoke and smells that set you off.
In one trial of 87 people, 88% of those who had the training were judged to have succeeded, compared with 14% in the control group. In a multicenter trial, coughing fell 41% relative to the control group, and the effect lasted to 3 months. It takes a few sessions with an experienced therapist; reading about it once is not enough.
Evidence · What the two trials actually did
The Australian trial (Vertigan 2006): 87 people still coughing despite medication were randomly assigned to speech therapy or a placebo program, four sessions each. In the training group, the cough score fell from 8.9 to 4.6; by clinical judgment, 88% of the training group were rated successful versus 14% with placebo. The program had four parts: explaining that coughing has no physiological benefit and can be brought under voluntary control; recognizing the warning sign before a cough and replacing it with a modified swallow, pursed-lip breathing or relaxed-throat breathing; reducing throat irritation by drinking more and avoiding irritants; and psychological education, including accepting that it takes work and setting realistic goals.The UK multicenter trial (Chamberlain Mitchell 2017): 75 people with refractory cough had four weekly one-to-one sessions (education, throat hydration and hygiene, cough suppression techniques, breathing exercises, counseling), while the control group got healthy-lifestyle advice only. Cough-related quality of life improved by 1.53 points more, objectively recorded 24-hour cough frequency fell 41% relative to control, and the effect lasted to 3 months. Notably, capsaicin cough sensitivity did not change. One reading is that the training changes how a person responds to the urge to cough, not the nerve endings themselves.
Chapter 7
When to see a doctor
Most coughs are not serious, but don't wait at home with any of these:
Coughing up blood, even streaks in your phlegm: see a doctor soon. If you cough up a lot of blood, can't get your breath or have chest pain, go to the emergency department now.Over 40, especially if you smoke, with a cough plus weight loss, poor appetite, breathlessness or chest pain: get checked soon.A cough that drags on with fever, night sweats, weight loss or exhaustion needs a tuberculosis test. TB spreads through the air by coughing, so wear a mask where you can until it is ruled out.Bouts of coughing, vomiting afterward, or a whoop on breathing in may be whooping cough: see a doctor.
Children are different:
A toddler who was fine and suddenly starts choking and coughing may have inhaled something: seek care now, and go to the emergency department now if breathing is labored or the lips turn blue.A wet cough with phlegm lasting more than 4 weeks needs a doctor; bacterial bronchitis can be cured with the right antibiotic.No honey under age 1.
Coughing up blood, even streaks in your phlegm: see a doctor soon. If you cough up a lot of blood, can't get your breath or have chest pain, go to the emergency department now.Over 40, especially if you smoke, with a cough plus weight loss, poor appetite, breathlessness or chest pain: get checked soon.A cough that drags on with fever, night sweats, weight loss or exhaustion needs a tuberculosis test. TB spreads through the air by coughing, so wear a mask where you can until it is ruled out.Bouts of coughing, vomiting afterward, or a whoop on breathing in may be whooping cough: see a doctor.
Children are different:
A toddler who was fine and suddenly starts choking and coughing may have inhaled something: seek care now, and go to the emergency department now if breathing is labored or the lips turn blue.A wet cough with phlegm lasting more than 4 weeks needs a doctor; bacterial bronchitis can be cured with the right antibiotic.No honey under age 1.
Red flag · Why blood and weight loss matter
A study in Exeter, UK, went through two years of primary-care records before diagnosis for 247 people over 40 with lung cancer and compared them with 1,235 people of the same age and sex. Seven symptoms were independently linked to lung cancer: coughing up blood, weight loss, loss of appetite, breathlessness, chest pain, fatigue and cough; so were finger clubbing (thickened fingertips with curved nails), a high platelet count, abnormal lung function, and smoking. With the last six months before diagnosis removed, coughing up blood, breathlessness and abnormal lung function were still linked to lung cancer, meaning these signals can appear early.Tuberculosis gives different clues: the World Health Organization lists a long-lasting cough (sometimes with blood), chest pain, weakness, weight loss, fever and night sweats as common symptoms.
Most of the time these symptoms are neither cancer nor TB, but they are a reason to have a doctor examine you in person, the sooner the better.
Red flag · Why children's coughs are different
In children, chronic cough is counted from 4 weeks, not 8. Their airways are built differently and are more easily irritated, and both the control of the cough reflex and the immune system are still maturing, so a cough is more often a symptom of another illness that needs to be found.A few ways children differ from adults:
When a previously healthy preschool child suddenly starts coughing, the guideline says to think of an inhaled object, which often needs a bronchoscopy to remove.Protracted bacterial bronchitis is a common cause of wet cough in children and used to be missed: a wet cough lasting more than 4 weeks, no signs pointing to another cause, and recovery after 2 to 4 weeks of a suitable oral antibiotic. It may be a forerunner of bronchiectasis, so it is worth pinning down.The nerve-acting cough drugs used in adults are not used in children.
References · 14
- Morice, A. H., Millqvist, E., Bieksiene, K., Birring, S. S., Dicpinigaitis, P., Domingo Ribas, C., Hilton Boon, M., Kantar, A., Lai, K., McGarvey, L., Rigau, D., Satia, I., Smith, J., Song, W.-J., Tonia, T., van den Berg, J. W. K., van Manen, M. J. G., & Zacharasiewicz, A. (2020). ERS guidelines on the diagnosis and treatment of chronic cough in adults and children. European Respiratory Journal, 55(1), 1901136. Chronic cough: over 8 weeks in adults, 4 weeks in children; global adult prevalence about 10% (meta-analysis). Cough is a vagal reflex; a poor cough reflex leads to recurrent aspiration; polymodal receptors such as TRPV1, TRPA1 and P2X3 on airway nerve endings respond to gastric fluid, acid, smoke, particulates and hyper- or hypotonicity, and ATP from stressed cells is an important stimulus; receptive fields also in lung parenchyma, pharynx, oesophagus and the ear canal (Arnold's reflex); cortical influences modulate the reflex and women have a greater somatosensory cortical area devoted to cough; the system shows redundancy, plasticity and adaptation; most patients show cough reflex hypersensitivity, triggered by low-level stimuli such as cold air, perfumes, smoke and bleach; specialist-clinic patients two-thirds female, most often in their sixth decade. T2 (eosinophilic) inflammation in about a quarter (cough variant asthma, eosinophilic bronchitis). Non-acid and gaseous reflux may contribute and oesophageal dysmotility is highly prevalent in chronic cough. ACE inhibitor cough in about 15%; ACE inhibitors reset the reflex so timing may not match; angiotensin II antagonists do not affect the cough reflex; no patient with cough should be given an ACE inhibitor; bisphosphonates and calcium channel antagonists may worsen reflux and cough; prostanoid eye drops such as latanoprost may descend the lacrimal duct and irritate the pharynx. Smoking is the major remediable cause; smokers have suppressed capsaicin cough sensitivity and cough may transiently increase in the first month after quitting. Stress urinary incontinence, interference with speech and depression are the most impactful complications; women with cough and incontinence have worse quality of life, and incontinence is rarely discussed, so it should be asked about. Initial assessment excludes malignancy, infection, foreign body and ACE inhibitor use; spirometry and chest X-ray; routine chest CT not suggested when X-ray and examination are normal (conditional, very low). Treatment is by sequential therapeutic trials, one agent at a time, stopped if no response; morphine responds within a week, ICS may take a month; if successful continue several months to let neuronal hypersensitivity resolve, then withdraw to test for remission. Short ICS trial 2-4 weeks (conditional, low): of ten RCTs, two in unselected chronic cough found benefit, while in non-asthmatic cough (negative methacholine) ICS was not superior to placebo. Short anti-leukotriene trial 2-4 weeks, particularly in asthmatic cough (conditional, low). Anti-acid drugs not routinely (conditional, low): no benefit over placebo without acid reflux, modest at most with it; high-dose esomeprazole for 12 weeks in patients with rare or no heartburn gave no benefit. Low-dose morphine in refractory cough (strong, moderate); gabapentin or pregabalin (conditional, low), limited by side effects such as dizziness, fatigue, cognitive changes, nausea and blurred vision; cough control therapy (physiotherapy, speech and language therapy) suggested (conditional, moderate). Children: differences in airway morphology, vulnerability, cough-reflex control and immune maturation make cough a symptom of an underlying disease; sudden cough in a healthy preschool child may be foreign-body aspiration requiring bronchoscopy; protracted bacterial bronchitis, a previously unrecognised common cause of wet cough, is defined by continuous wet cough over 4 weeks, no other pointers, and resolution after 2-4 weeks of an appropriate oral antibiotic, and may precede bronchiectasis; neuromodulators not used in children (full text PMC6942543; PMID 31515408). 10.1183/13993003.01136-2019
- Irwin, R. S., French, C. L., Chang, A. B., Altman, K. W., & CHEST Expert Cough Panel. (2018). Classification of cough as a symptom in adults and management algorithms: CHEST guideline and expert panel report. Chest, 153(1), 196-209. Acute cough under 3 weeks (mostly viral respiratory infection), subacute 3-8 weeks (mostly postinfectious cough, exacerbations of asthma or COPD, upper airway cough syndrome), chronic over 8 weeks (upper airway cough syndrome, asthma, GERD, nonasthmatic eosinophilic bronchitis, combinations; less commonly miscellaneous conditions and atopic cough in Asian countries). Evidence quality low (abstract, PMID 29080708). 10.1016/j.chest.2017.10.016
- Hamilton, W., Peters, T. J., Round, A., & Sharp, D. (2005). What are the clinical features of lung cancer before the diagnosis is made? A population based case-control study. Thorax, 60(12), 1059-1065. 247 lung cancers in people over 40 and 1,235 controls matched by age, sex and practice in all 21 Exeter general practices; the whole primary care record for 2 years before diagnosis was coded. Haemoptysis, weight loss, loss of appetite, dyspnoea, chest pain, fatigue and cough, finger clubbing, thrombocytosis and abnormal spirometry were independently associated with lung cancer, as was smoking; excluding the final 180 days before diagnosis, haemoptysis, dyspnoea and abnormal spirometry remained associated (abstract, PMID 16227326). 10.1136/thx.2005.045880
- Dicpinigaitis, P. V. (2014). Effect of viral upper respiratory tract infection on cough reflex sensitivity. Journal of Thoracic Disease, 6(Suppl 7), S708-S711. Capsaicin challenge studies show a transient cough hyperresponsiveness during a cold that reverts to normal by 4-8 weeks after infection; proposed mechanisms include cytokines, neurotransmitters, leukotrienes, increased neural receptors, reduced neutral endopeptidase activity and mucus hypersecretion; the urge to cough is also transiently enhanced; a cold may trigger chronic refractory cough in a subgroup (abstract, PMID 25383204). 10.3978/j.issn.2072-1439.2013.12.02
- Braman, S. S. (2006). Postinfectious cough: ACCP evidence-based clinical practice guidelines. Chest, 129(1 Suppl), 138S-146S. Cough persisting over 3 weeks after a cold, lasting no more than 8 weeks (subacute), normal chest radiograph, usually resolves on its own; thought due to airway inflammation and epithelial disruption, mucus hypersecretion and transient airway and cough receptor hyperresponsiveness. Antibiotics have no role except bacterial sinusitis or early pertussis; inhaled ipratropium may help. Paroxysms, posttussive vomiting or an inspiratory whoop: diagnose pertussis unless proven otherwise; highly contagious, macrolide early; vaccine available for adults and children (abstract, PMID 16428703). 10.1378/chest.129.1_suppl.138S
- Oduwole, O., Udoh, E. E., Oyo-Ita, A., & Meremikwu, M. M. (2018). Honey for acute cough in children. Cochrane Database of Systematic Reviews, 4, CD007094. 6 RCTs, 899 children aged 12 months to 18 years. Honey probably reduces cough frequency more than no treatment or placebo (moderate certainty), may be similar to dextromethorphan, may be better than diphenhydramine (low certainty); probably more effective than placebo or salbutamol for up to three days, no advantage beyond three days. Most children received treatment for one night; no strong evidence for or against honey (abstract, PMID 29633783). 10.1002/14651858.CD007094.pub5
- Centers for Disease Control and Prevention. (2026). Botulism prevention. Honey can contain the bacteria that cause botulism; do not feed honey to a child who is younger than 1 year old. www.cdc.gov/botulism/prevention/index.html
- Smith, S. M., Schroeder, K., & Fahey, T. (2014). Over-the-counter (OTC) medications for acute cough in children and adults in community settings. Cochrane Database of Systematic Reviews, 11, CD001831. 29 placebo-controlled trials, 4,835 people; antitussives, expectorants, mucolytics, antihistamine-decongestant combinations gave variable or conflicting results; no good evidence for or against OTC medicines in acute cough (abstract, PMID 25420096). 10.1002/14651858.CD001831.pub5
- Morice, A. H., Millqvist, E., Belvisi, M. G., Bieksiene, K., Birring, S. S., Chung, K. F., Dal Negro, R. W., Dicpinigaitis, P., Kantar, A., McGarvey, L. P., Pacheco, A., Sakalauskas, R., & Smith, J. A. (2014). Expert opinion on the cough hypersensitivity syndrome in respiratory medicine. European Respiratory Journal, 44(5), 1132-1148. ERS Task Force interview of 44 opinion leaders: cough hypersensitivity syndrome, troublesome coughing triggered by low levels of thermal, mechanical or chemical exposure, endorsed as a valid and useful concept; the role of acid suppression in reflux cough was questioned (abstract, PMID 25142479). 10.1183/09031936.00218613
- Lai, K., Chen, R., Lin, J., Huang, K., Shen, H., Kong, L., Zhou, X., Luo, Z., Yang, L., Wen, F., & Zhong, N. (2013). A prospective, multicenter survey on causes of chronic cough in China. Chest, 143(3), 613-620. 704 adults in five regions of China; cause found in 90.9%: cough variant asthma 32.6%, upper airway cough syndrome 18.6%, eosinophilic bronchitis 17.2%, atopic cough 13.2%, together 75.2-87.6% across regions; gastroesophageal reflux-related cough 4.6%; season, sex and age not associated with the spectrum (abstract, PMID 23238526). 10.1378/chest.12-0441
- Dicpinigaitis, P. V. (2006). Angiotensin-converting enzyme inhibitor-induced cough: ACCP evidence-based clinical practice guidelines. Chest, 129(1 Suppl), 169S-173S. Dry persistent cough is a class effect; likely bradykinin and substance P (degraded by ACE) and prostaglandins. Reported incidence 5-35%; onset within hours of the first dose to months later; resolution typically 1-4 weeks after stopping, may linger up to 3 months. The only uniformly effective treatment is stopping the drug; cough with angiotensin-receptor blockers similar to control; in a patient with chronic cough consider an ACE inhibitor causative regardless of timing (abstract, PMID 16428706). 10.1378/chest.129.1_suppl.169S
- World Health Organization. (2026). Tuberculosis [Fact sheet]. TB spreads through the air when people with TB cough, sneeze or spit. Common symptoms: prolonged cough (sometimes with blood), chest pain, weakness, fatigue, weight loss, fever and night sweats. www.who.int/news-room/fact-sheets/detail/tuberculosis
- Vertigan, A. E., Theodoros, D. G., Gibson, P. G., & Winkworth, A. L. (2006). Efficacy of speech pathology management for chronic cough: a randomised placebo controlled trial of treatment efficacy. Thorax, 61(12), 1065-1069. 87 patients with cough persisting despite medical treatment; four sessions with a speech pathologist. Cough score 8.9 to 4.6 in the treatment group; clinically successful in 88% versus 14% with placebo. Programme (Table 2): education that cough has no physiological benefit and can be brought under voluntary control; identifying the warning sign of a coming cough and replacing it with a modified swallow, pursed-lip breathing or relaxed throat breathing; reducing laryngeal irritation by increasing hydration and avoiding irritants; psycho-educational counselling (abstract, PMID 16844725; full text PMC2117063). 10.1136/thx.2006.064337
- Chamberlain Mitchell, S. A., Garrod, R., Clark, L., Douiri, A., Parker, S. M., Ellis, J., Fowler, S. J., Ludlow, S., Hull, J. H., Chung, K. F., Lee, K. K., Bellas, H., Pandyan, A., & Birring, S. S. (2017). Physiotherapy, and speech and language therapy intervention for patients with refractory chronic cough: a multicentre randomised control trial. Thorax, 72(2), 129-136. 75 patients; four weekly sessions of education, laryngeal hygiene and hydration, cough suppression techniques, breathing exercises and psychoeducational counselling versus healthy-lifestyle advice. Leicester Cough Questionnaire improved 1.53 points more; cough frequency fell 41% relative to control; gains sustained to 3 months; capsaicin cough sensitivity unchanged (abstract, PMID 27682331). 10.1136/thoraxjnl-2016-208843