Mind & body, in brief

A cough is one movement in three parts: a deep breath in, a hard squeeze against a shut throat, then the throat snaps open and the air leaves fast. [1]

It guards the lungs. It clears food, drink, smoke and mucus out of a tube that has no other way to empty. [1][41]

Doctors call a cough chronic once it has lasted more than eight weeks. In children of fourteen and under the line is four weeks. [1]

About one adult in ten in the world has one. [2]

Many keep coughing long after the illness that started it has gone, because the reflex itself has become easier to set off. [8]

The nerves that carry the cough signal sit in the throat and airway and run to the brainstem. Touch is enough: a camera brushing the voice box set one woman coughing repeatedly. [8][36]

Those nerves carry a tiny gate called P2X3, which opens when a cell nearby leaks the fuel molecule ATP. [4]

The same gate sits on the nerves that carry taste, and on nerves that carry pain. [4]

So the first drug built to shut that gate, gefapixant, cut coughing in large trials and left many people unable to taste their food. [6]

The trade is now the main brake on the whole drug class. Reviews list taste loss as the reason a working treatment is hard to use. [3][6]

There is still no test that shows a stubborn cough is real. No blood marker, no scan, nothing to point at. [7]

Chemists are not trying to aim better. They are looking for a second doorway into the same gate, in the hope that cough closes and taste does not. [5][4]

Why it matters. The next test is whether a second doorway into the same gate quiets a cough and leaves taste alone. Until then the treatment that works is the one people cannot bear. [5][3]

Up to 75% of people whose cough comes from acid coming back up the gullet never feel heartburn or a sour taste. The signal runs by nerve, not by burn. [2]

Why it matters. It is the plainest example of a cause that shows up nowhere near where it starts.

In a 30-patient trial, mepolizumab cut blood eosinophils, a type of inflammatory white cell, by 237.7 cells per microlitre and changed 24-hour coughing by +18.0%, which is nothing. [15]

Why it matters. The inflammation everyone suspected turned out not to be what was driving the cough.

In 44 people with scarred lungs, 5 mg of controlled-release morphine twice a day cut daytime coughing by 39.4%. Nausea hit 14% and constipation 21%. [14]

Why it matters. An old, cheap drug beat everything designed for the job.

Sufentanil, a strong painkiller given at the start of an operation, made 42.66% of patients cough. A different opioid given first brought that to 0%. [16]

Why it matters. One family of drugs both stops coughing and starts it, depending on which nerve it reaches first.

Between 2.5% and 35% of people on ACE inhibitors report a dry cough. The enzyme those drugs block also clears bradykinin, an irritant, out of the airway. [17]

Why it matters. Blocking the enzyme is the treatment and the cough at the same time.

Cleveland Clinic, a US hospital group, lists a reduced or metallic taste among the less common effects of ACE inhibitors, alongside the dry cough. [18]

Why it matters. Cough and taste turn up together again, on a completely different drug.

Among 107 patients in the United Arab Emirates, those carrying one copy each of two versions of the ACE gene were 2.34 times more likely to cough on the drug. [19]

Why it matters. The same pill is a different drug depending on the body it lands in.

Across 72,534 people in the UK and 255,806 in China, five-year deaths were 3.45% on ACE inhibitors and 3.04% on the newer alternative. [20]

Why it matters. Two large databases suggest the substitute is not simply the same drug without the cough.

Codeine, cloperastine and gefapixant all cut coughing in guinea pigs given citric acid. Dextromethorphan and levodropropizine, both sold widely, did not. [21]

Why it matters. Two of the most common ingredients in a cough bottle failed the simplest test there is.

A 2025 review concluding that guaifenesin and dextromethorphan work lists Haleon as its funder. The review reports a high placebo response across the studies it covers. [22]

Why it matters. The review reaching the favourable verdict was paid for from inside the industry it judges.

Sixteen healthy people inhaled capsaicin, the heat chemical in chilli. After a placebo they wanted to cough less, and the brainstem sites where airway nerves land went quieter. [9]

Why it matters. Belief reaches the reflex itself, not just the report of it.

Dextromethorphan blocks the NMDA receptor and switches on the sigma-1 receptor. Paired with other drugs it is approved for depression and for uncontrollable crying. [23]

Why it matters. The ingredient in a cold remedy is doing several unrelated jobs at once.

The US National Library of Medicine lists dextromethorphan overdose as a recognised emergency, and notes the drug is sold under street names. [24]

Why it matters. The same molecule is a supermarket purchase, a psychiatric medicine and a drug of abuse.

Researchers in Texas assessed dextromethorphan combined with quinidine for irritability in Huntington's disease, an inherited condition that damages the brain. [25]

Why it matters. A cough ingredient keeps being tried on the brain, because that is where it acts.

Among 10,385 people with a cough of weeks or months, 42.7% were prescribed centrally acting cough drugs. Past 57 days, constipation odds rose 1.80 times and nausea 2.06. [26]

Why it matters. The gut pays for what the brainstem is given.

A multi-centre study across Indian hospitals followed patients with a dry cough who had failed non-opioid remedies, and gave them codeine with triprolidine. [27]

Why it matters. Where new drugs are out of reach, the old opioid is still the fallback.

Jacky Smith, a lung specialist in Manchester, England, says syrups soothe the throat and cannot touch the virus, and cheaper supermarket versions work as well as branded ones. [28]

Why it matters. The active part is the coating, and coating is not proprietary.

Cleveland Clinic describes honey as a reasonable option for a mild cough in adults and children over one, and warns it can cause infant botulism in babies under a year. [29]

Why it matters. The most-recommended home remedy carries an age limit most people have never heard.

A scoping review found 35 studies of honey, propolis and other bee products in children's infections, mostly small trials, and called the quality inconsistent. [30]

Why it matters. Widely used is not the same as well tested, in either direction.

A toxicology review catalogues the active compounds in honey, including ones that can be harmful, and calls the substance a liquid with a dark side. [31]

Why it matters. Natural does not mean nothing is happening.

Of 1,012 patients surveyed in primary care, most rated home remedies effective: 77% for onion syrup for a cough, 94% for thyme inhalation for a cold. [32]

Why it matters. Illnesses that end on their own hand credit to whatever was taken last.

A review finds zinc supplements consistently reduce how often children get chest and throat infections. As a treatment during an acute infection the evidence is much weaker. [33]

Why it matters. Preventing an illness and shortening one are separate questions, and the same supplement answers only the first.

Guinea pigs exposed to nitric oxide over a long period coughed far more readily at a chilli challenge. There was no airway inflammation to explain it. [34]

Why it matters. The nerve can be turned up without anything looking inflamed.

Researchers in Shanghai, China trace the shift from psychogenic cough to somatic cough syndrome. They note that neither term has ever had a clear definition or agreed diagnostic criteria. [35]

Why it matters. A label with no criteria behind it still decides how a patient is treated.

A 62-year-old woman coughed daily for two years. Scans found a widened jugular vein. Carbamazepine, an anti-seizure drug, with codeine nearly stopped it. [37]

Why it matters. It shows the range of things that can press on an airway nerve.

Of 231 patients at one cough clinic, 164 were women. Men were more often found to have a cough coming from the nose and throat, 75% against 53%, or sleep apnoea, 21% against 6%. [12]

Why it matters. Same symptom, different causes, split along a line nobody has explained.

In a north-west London dataset of 2,109,430 people, chest X-rays around a chronic cough diagnosis rose from 6,535 to 12,880 and lung function tests from 5,791 to 8,720. [10]

Why it matters. With no test for the condition, the system runs the tests it has.

At the Mayo Clinic cough clinic, 56 patients were considered to have refractory cough. A records review later found a confirmed cause in 35 of them, or 62%. [48]

Why it matters. Most of the mystery was missing information, not missing biology.

Of 113 Taiwanese patients reporting complications, 46.0% had chest pain and 23.0% had urinary incontinence. A third of everyone surveyed had disturbed sleep, and self-paid costs ran about 94 US dollars a month. [13]

Why it matters. The damage is mechanical as well as social, and it is paid for privately.

In 40 healthy people, voluntary throat clearing moved air far more weakly than either a voluntary cough or a reflex one. [40]

Why it matters. The two sound alike to a clinician and do different amounts of work.

Acoustic software can log every cough a person makes, day after day, without recording speech. Trials have started using the count as an endpoint. [38]

Why it matters. A symptom that was only ever described can now be measured.

In children with neuromuscular disorders, which weaken the muscles used to breathe, a cough is too weak to clear the airway, and chest infections follow. [42]

Why it matters. The reflex everyone wants quieted is the one they are missing.

The COASESS study enrolled 303 patients at ten university hospitals. Those with asthma and lung scarring carried a heavier cough burden than those with COPD or bronchiectasis. [39]

Why it matters. The same symptom is not the same weight in every disease.

An English NHS hospital publishes a cough-suppression programme taught by physiotherapists, built on exercises rather than any drug. [41]

Why it matters. For a reflex with no proven pill, training the reflex is what is left.

A review maps the nerve circuits running from the airway to the brain, which set breathing, trigger coughing and shift mood. [43]

Why it matters. Coughing sits on the same wiring as feeling ill.

A review argues the nose and lungs carry bacterial communities that signal to the brain, a route studied far less than the gut. [44]

Why it matters. The airway is being read as a sense organ, not just a pipe.

The bony ridges inside the nose stir the incoming air into turbulence, which lets the nose filter and moisten it before it reaches the lungs. [50]

Why it matters. Most of what protects the airway happens before any reflex is needed.

A 2024 review of stubborn cough describes injections that numb the superior laryngeal nerve, which serves the voice box, alongside behavioural therapy, as options now in use. [46]

Why it matters. If the fault is a nerve, the treatments start looking like nerve treatments.

Among 203 paediatricians surveyed in Turkiye, those in private practice were 2.72 times more likely to give medicine for a child's cough, and reached more often for herbal remedies. [47]

Why it matters. The same viral cough gets a different answer depending on who is paying.

A 58-year-old man began the usual alternative to an ACE inhibitor and, six months later, his lips and face swelled. It settled only when the drug was stopped. [49]

Why it matters. The replacement chosen to avoid a cough carries a rarer problem of its own.