Quick answer: in adults, a cough that lasts more than eight weeks is called chronic. The three most common causes are postnasal drip (upper airway cough syndrome), asthma and acid reflux. Smoking, certain blood pressure medicines, lingering effects of an infection and lung conditions are other causes. Coughing blood, weight loss and fever need prompt attention.
How long is too long?
- Acute cough: under 3 weeks, usually from a cold or flu
- Subacute cough: 3 to 8 weeks, often lingering after an infection
- Chronic cough: more than 8 weeks
A cough after a chest infection can linger for weeks, which is common. If it goes on for more than eight weeks, or is getting worse, it’s time for a proper check.
The “big three” causes
1. Upper airway cough syndrome (postnasal drip). Mucus drips from the nose and sinuses down the back of the throat, causing constant throat clearing and a tickle. It is linked to allergies, colds and sinus problems. A cough that is worse when lying down, or comes with a blocked or runny nose, points here.
2. Asthma, including cough-variant asthma. Some people with asthma have cough as their main or only symptom, often dry, worse at night, with exercise or cold air, or around triggers such as dust and pollen. Our guide on reducing asthma triggers at home can help.
3. Gastroesophageal reflux (GERD). Stomach acid irritates the throat and airways. Clues include heartburn, a sour taste, hoarseness and cough after meals or on lying down. Some people have reflux cough without heartburn.
Other common causes
- Smoking and chronic bronchitis or COPD: a long-term “smoker’s cough” with phlegm
- ACE inhibitor medicines (such as lisinopril, enalapril, ramipril) used for blood pressure or heart conditions. These cause a dry, tickly cough in a minority of people, which can start weeks or months after beginning the medicine. Don’t stop it yourself, but ask your doctor about alternatives.
- After an infection: a cough that lingers after a cold, flu or whooping cough (pertussis)
- Bronchiectasis, a lung condition with repeated infections and phlegm
- Heart failure: cough with breathlessness, especially lying flat, and ankle swelling. See our guide on swollen ankles.
- Tuberculosis (TB): an important cause in regions where it is common, particularly with weight loss, fever and night sweats
- Lung cancer or other lung diseases, which is why red flags matter
- Environmental irritants: dust, smoke, fumes and strong scents
Red flags: see a doctor promptly
Seek care soon if your cough comes with:
- Coughing up blood
- Unexplained weight loss
- Night sweats or fever
- Shortness of breath or wheezing
- Chest pain
- Hoarseness lasting more than three weeks
- Difficulty swallowing
- Swelling in the legs
- You are a smoker or ex-smoker over 50
Get emergency care if you have severe shortness of breath, blue lips, or choking.
What your doctor may do
- Ask about your cough, triggers, smoking, medicines and heartburn
- Listen to your chest
- Order a chest X-ray
- Test lung function with spirometry
- Check for sinus or allergy problems
- Review your medicines
- In some cases, test for TB, or order a CT scan or a stomach and throat assessment
Often doctors treat the most likely cause first, for example a nasal spray for postnasal drip, an inhaler for asthma, or reflux treatment, and see if the cough improves.
What can help at home
- Stop smoking and avoid second-hand smoke
- Drink fluids and use a humidifier if the air is dry
- Try honey in warm water or tea for adults, which has some evidence for soothing cough
- Rinse your nose with saline if you have postnasal drip
- Raise the head of your bed and avoid large or late meals if you have reflux
- Avoid known triggers like dust and strong perfumes
Cough suppressants are not a long-term solution, since the aim is to find and treat the cause.
Frequently asked questions
Can a chronic cough be caused by anxiety?
Rarely, and only after other causes have been ruled out. A habit cough is a diagnosis of exclusion.
Why is my cough worse at night?
Lying flat worsens postnasal drip and reflux, and asthma often flares at night.
Is a dry cough or a wet cough more worrying?
Neither type is automatically worse. What matters is how long it lasts, whether it’s getting worse, and the red flags above.
Can allergies cause a cough for months?
Yes, especially if they cause postnasal drip or trigger asthma.
Cura Editorial Team
Contributor at Cura Health Journal.