After a cold or flu, coughs can linger for three to four weeks as the airways recover — this is completely normal and usually improves gradually each week. You probably do not need to worry if the cough is getting slowly better week by week, you feel otherwise well, you have had a recent cold or virus, and the cough is less than three weeks old.
When to Take a Persistent Cough Seriously
See your GP if your cough lasts more than three weeks, is getting worse rather than better, wakes you at night regularly, makes you breathless, or comes with wheezing. Seek urgent specialist assessment if you have blood in your sputum even in small amounts, significant unexplained weight loss, drenching night sweats, chest pain, or severe breathlessness. These symptoms always warrant prompt investigation.
Asthma: The Most Common Cause I See
Asthma is the most common underlying cause of chronic cough in my practice. Many patients do not realise they have asthma — they simply think they have a persistent bad cough. Signs that asthma may be responsible include a cough that is worse at night or early in the morning, symptoms triggered by exercise, cold air, or laughing, and chest tightness or wheeze accompanying the cough.
Other Common Causes of Chronic Cough
Post-nasal drip — mucus dripping down the back of the throat from sinuses or allergies — causes constant throat clearing and is typically worse when lying down. Acid reflux (GERD) causes stomach acid to irritate the airways, producing a cough that worsens after eating or lying down, often with heartburn or a sour taste. ACE inhibitor blood pressure tablets cause a chronic dry cough in up to 20% of people who take them — if your cough started after beginning new medication, this is worth checking.
COPD and Less Common but Serious Causes
In current or former smokers, a persistent cough producing phlegm — particularly in the mornings — may be an early sign of COPD. Less common but serious causes include lung infections including tuberculosis, bronchiectasis, interstitial lung disease, and lung cancer particularly in those with a significant smoking history. This is precisely why investigation matters rather than dismissing a chronic cough.
What I Look For at Your Consultation
When you come to see me with a chronic cough, I will take a detailed history of when it started, what makes it better or worse, and any associated symptoms. I will examine your chest and arrange appropriate investigations including spirometry, chest X-ray, CT scan if indicated, allergy testing, or reflux assessment. In some cases, bronchoscopy is needed to look directly inside the airways when other tests have not provided an answer.
The Bottom Line
A cough lasting more than three weeks needs investigation. Most causes are entirely treatable — but only once we know what we are dealing with. I have seen too many patients wait months or years before seeking help. Early investigation leads to faster diagnosis, effective treatment, and in some cases, genuinely life-changing outcomes.
Signs You May Have COPD
- Cough lasting more than three weeks — see your GP
- Cough with blood in sputum — seek urgent specialist assessment
- Cough worse at night or triggered by exercise — possible asthma
- Cough that started after new blood pressure medication — check with your doctor
- Cough with weight loss, night sweats, or chest pain — do not delay
Respiratory Services
If you are experiencing ongoing breathing problems, specialist respiratory assessment may help clarify the diagnosis and guide treatment.
- Asthma Diagnosis and Assessment
- Chronic Cough Investigation
- Spirometry and Lung Function Testing
- Allergy and Trigger Testing
- Bronchoscopy if Required
Frequently Asked Questions
How long is too long for a cough?
A cough lasting more than three weeks should be assessed by your GP. If it persists beyond eight weeks despite initial treatment, specialist assessment is recommended to identify the underlying cause.
Can asthma cause a persistent cough without wheezing?
Yes. Cough-variant asthma is a recognised condition where chronic cough is the primary or only symptom, without the classic wheeze. Many patients are surprised to receive an asthma diagnosis when they have never experienced breathlessness.
Could my blood pressure medication be causing my cough?
Possibly. ACE inhibitor medications, commonly prescribed for high blood pressure and heart conditions, cause a persistent dry cough in up to 20% of patients. If your cough started after beginning a new medication, mention this to your GP — an alternative medication is usually available.
When does a persistent cough need a chest X-ray?
A chest X-ray is typically recommended when a cough has lasted more than three weeks without an obvious cause, particularly in smokers or ex-smokers, or when red flag symptoms such as weight loss, night sweats, or blood in sputum are present.
What happens at a specialist cough consultation?
Dr Suman Paul will take a detailed history, examine your chest, and arrange appropriate investigations including spirometry, imaging, allergy testing, or reflux assessment. You will leave with a clear explanation of likely causes and a personalised management plan.
Investigate Your Persistent Cough in Liverpool
If you have had a cough for more than three weeks that is not improving, do not keep waiting. A specialist assessment can identify the cause and guide effective treatment. Private appointments are available quickly at our Liverpool and Manchester clinics.
Book a Consultation — Call 0161 832 2111
About Dr Suman Paul
Dr Suman Paul is a Consultant Respiratory Physician with extensive experience diagnosing and managing complex lung diseases including COPD, asthma, pulmonary fibrosis and lung cancer.
Private respiratory consultations are available at Pall Mall Medical Liverpool, 5 St Pauls Square, Liverpool, L3 9SJ.
