Dry Cough That Lingers: Why, and When to Go

Key takeaways

A lingering dry cough is a SIGN that needs a cause found, not an illness to be soothed with cough syrup. People who have coughed for months have usually been through several syrups without anyone listening to their chest or asking what they are taking.
The mark worth remembering is THREE WEEKS. According to NHS, a cough lasting more than three weeks should be seen; according to CDC, the symptoms of an episode of acute bronchitis last less than three weeks, and beyond that mark it is time to be looked at.
The most overlooked cause is the tablet taken every morning: according to MedlinePlus, ACE-inhibitor blood-pressure medicines can cause a dry cough, and the cough can begin after you have been on the medicine for a long time.
But DO NOT stop the medicine yourself. MedlinePlus says it plainly: do not stop taking the medicine before you talk to your doctor. Your job is to tell the doctor who prescribed it, so they can consider lowering the dose or changing the medicine.
In small children: according to CDC, over-the-counter cough and cold medicines are NOT recommended for children under 6 and can cause serious side effects. Honey can be used for children aged 1 and over, and must NOT be given to a baby under 1.

The most important thing first: a lingering dry cough is a SIGN that needs a cause found, not an illness to be soothed with cough syrup. Plenty of people cough for months without anyone listening to their chest or reading their prescription back to them.

Recognising it: a dry cough is a cough without phlegm

A dry cough is a cough that brings nothing up: you cough and the throat is still dry and raw. According to NHS, a cough usually clears on its own in around three to four weeks — so what deserves attention is not the sound of it but the TIME: how long it has been going on, and whether it is getting worse. A cough with phlegm is a different subject, and this site has an article of its own on it.

Why a dry cough happens

According to NHS, the causes of a cough include colds and flu, smoking, acid reflux, allergies, infections, and mucus running down the throat from behind the nose:

Common cause	What points towards it
After a viral illness	The fever and the runny nose have gone, and the dry cough is what is left
Acid reflux	Coughing at night, or after eating
ACE-inhibitor blood-pressure medicine	It started after a medicine was added or changed
Allergy, asthma	Worse at night and in the early morning; wheezing
Tobacco smoke, dust, dry air	Coughing near the source, easing somewhere else
Mucus running down the throat from behind the nose	Having to clear the throat constantly, worst on waking

Reflux and asthma

According to NIDDK, a persistent cough and hoarseness are among the signs of complications of reflux in the mouth, the throat or the lungs. Many people only cough and have never felt heartburn at all. With asthma, the clue is the TIME of the cough: according to NHLBI at NIH, the cough in asthma is worse at night or in the early morning, and waking at night because of coughing is a sign that should be looked at.

If you take blood-pressure medicine

According to MedlinePlus, ACE-inhibitor blood-pressure medicines can cause a dry cough. That cough may settle by itself after a while, and it may also appear only once you have been on the medicine for a long time — so “I have taken it for years without trouble” does not rule it out.

What to do, exactly as MedlinePlus puts it: tell your doctor if you develop a cough — sometimes lowering the dose helps, and sometimes the doctor changes you to a different medicine. And the most important sentence of all: DO NOT stop the medicine before you talk to your doctor. Uncontrolled blood pressure is more dangerous than a cough.

What to do straight away

Write it on paper and take it to the appointment: roughly when the cough started, what time of day it is worst, and a LIST of every medicine you take, supplements included.
According to NHS: rest and drink enough fluids. According to CDC, honey soothes a cough in adults and children aged 1 and over — do NOT give honey to a baby under 1.
Keep the air from getting too dry with a clean cool-mist humidifier; do not let an air conditioner blow straight into your face.
Give up tobacco smoke, both smoking and breathing other people's — something you can do immediately, without anyone's prescription.
If the cough is worse at night or after eating, do not eat and then lie straight down: according to NIDDK, leaving a few hours between the last meal and going to bed can make the symptoms easier.

What must NOT be done

Do NOT stop, reduce or change blood-pressure medicine yourself because you suspect it is causing the cough. According to MedlinePlus, do not stop the medicine before you talk to your doctor — take the box to the appointment and let the doctor decide.
Do NOT give small children over-the-counter cough or cold medicines: according to CDC these are not recommended for children under 6 and can cause serious, even life-threatening side effects.
Do NOT buy antibiotics yourself. According to CDC, antibiotics do nothing against a virus and will not make your cough better, while the side effects arrive in full.
Do NOT treat “no phlegm, no fever” as evidence that it is mild: a dry cough can still be asthma, reflux, or a lung condition that needs an image to see.

When you must go to hospital

GO TO EMERGENCY CARE NOW, or call 115 (the emergency number in Vietnam), if there is: difficulty breathing, gasping breaths, having to stop for breath mid-sentence; a wheeze or stridor; severe chest pain; coughing up a lot of blood, or bright red blood by the mouthful; blue lips or fingertips; new confusion, lethargy, hard to wake; a seizure. Anyone on blood-pressure medicine whose lips, tongue or face swell: according to MedlinePlus that may be a severe allergic reaction to the medicine and means emergency care. — BE SEEN THE SAME DAY, do not leave it until tomorrow, if: you cough up blood, even a little; the cough is worsening fast and you feel very unwell; the cough had eased and has come back worse; the glands in the neck are swollen and sore; or the person's immunity is reduced, for instance by chemotherapy or by diabetes. — BE SEEN WITHIN 24–72 HOURS if: the cough has gone past THREE WEEKS; you are losing weight for no clear reason; you have night sweats; you have been hoarse for a long time; the dry cough started after a medicine was added or changed; you wake at night because of coughing every night. — If you are not sure, ring and ask before deciding for yourself.

When to call a doctor

Put plainly: a lingering dry cough needs someone to listen to the chest and read the prescription back — two things an article cannot do. A chest image and lung-function testing have to be done at a medical facility.

A Y Te Xanh (GreenCare) doctor comes to the house to take the history, examine, measure the pulse, blood pressure, temperature and SpO₂, and say clearly which cases must be admitted; if nobody needs to come out yet, start with a remote consultation by video call. The medication review service reads the whole prescription and points out what is questionable so you can raise it with the doctor who prescribed it — we do not change or stop a medicine on your behalf. With a sign in the box above, go in first and call afterwards.

The three-week mark and the causes follow the NHS page on cough; honey, antibiotics and cough medicines in children follow the US CDC; ACE inhibitors follow MedlinePlus, reflux follows NIDDK, and asthma follows NHLBI. This article passes that on and does not replace being examined. Citing these bodies does not imply that they endorse Y Te Xanh or our services.

Need personalised advice for your loved one? Call our hotline 094 368 81 15 (24/7) — calling to ask a question or to book costs nothing. GreenCare has doctors who come to examine, nurses who carry out doctor's orders (injections, infusions, dressing changes), remote consultation by video call, and a review of the medicines you are taking; an in-depth remote consultation, or any one after the first, is a paid service. For children we take examination and acute care only — not long-term care at home, and not newborns or expectant mothers. We confirm we have staff in your area and provide transparent pricing before we begin.

Sources

NHS — Cough
CDC — Manage Common Cold

Frequently asked questions

I have had a dry cough for weeks and cough syrup is not helping — what should I do?

A third kind of syrup is not the next step — being seen is. According to NHS, a cough lasting more than three weeks is the point at which to see a doctor, and according to CDC the symptoms of an episode of acute bronchitis last less than three weeks, so beyond that mark it is time to be looked at rather than to wait longer. The reason syrup does not help is usually very simple: it quiets the cough reflex without touching the cause, and the cause may be reflux, asthma, an allergy, or the very medicine you are taking. Before you go, write down three things: roughly when the cough started, what time of day it is worst, and a list of every medicine and supplement you take.

I take blood-pressure medicine and have a dry cough — is it the medicine, and can I stop it?

It may well be the medicine, but stopping is not the answer. According to MedlinePlus at NIH, ACE-inhibitor blood-pressure medicines can cause a dry cough; that cough sometimes settles by itself after a while, and sometimes only starts once you have been on the medicine for a long time — so “I have taken it for years without trouble” does not rule it out. The right move is the one MedlinePlus names: tell your doctor you have developed a cough. Sometimes lowering the dose helps; sometimes the doctor changes you to a different medicine. But MedlinePlus is equally clear that you should not stop the medicine before you talk to your doctor: uncontrolled blood pressure is more dangerous than a cough. Swelling of the lips, tongue or face is a different matter entirely — according to MedlinePlus that may be a severe allergic reaction to the medicine and needs emergency care straight away.

What causes a dry cough at night?

The time of the cough is a genuinely useful clue, so tell the doctor about it. Two common directions are asthma and reflux. According to NHLBI at NIH, the cough in asthma is usually worse at night or in the early morning and disturbs sleep, and waking at night because of coughing is a sign that should be looked at by someone qualified; it often comes with wheezing, chest tightness or breathlessness. With reflux, according to NIDDK a persistent cough and hoarseness are among the signs of complications in the mouth, the throat or the lungs — and NIDDK notes that leaving a few hours between the last meal and going to bed can make night-time symptoms easier. Telling these two apart is the work of an appointment, not of guessing at home.

A dry cough with no fever and no phlegm — does it still need to be seen?

“No fever, no phlegm” is not evidence that it is mild — it only means a different problem, not a smaller one. What decides is still the time and what comes with it. According to NHS, see a doctor if the cough has gone past three weeks, if you are losing weight for no clear reason, or if your immunity is reduced, for instance by chemotherapy or by diabetes. According to CDC, you should be seen if you cough up blood, if you are short of breath, if the symptoms last more than three weeks, or if the episodes keep coming back. And however long you have been coughing, if there is difficulty breathing, severe chest pain, blood in the cough or blue lips, go to emergency care and stop counting days.

What can a child with a dry cough be given?

Before you think about medicine, know two age limits. According to CDC, over-the-counter cough and cold medicines are not recommended for children under 6 and can cause serious, even life-threatening side effects; and lozenges are not for children under 4. What CDC does name as usable: honey soothes a cough in adults and children aged 1 and over, but a baby under 1 must never be given honey. Beyond that it is the things that need no prescription: regular drinks, rest, air in the room that is not too dry, and nobody smoking in the house. If the child has difficulty breathing, fast breathing, the chest drawing in, blueness around the mouth or lethargy, go now and do not wait.