A persistent cough (chronic cough) is one that lasts longer than three weeks. While many coughs are caused by infections and settle on their own, a cough that continues or keeps returning may require further assessment.

Symptoms such as breathlessness, chest discomfort, or fatigue alongside a persistent cough can indicate an underlying respiratory condition.

Early assessment can help identify the cause and guide appropriate treatment.

What is a chronic cough?

Coughing is a reflex action that occurs when your body is trying to clear the airways of irritants like smoke or dust, or phlegm (thick mucus made by the cells lining the lungs and upper airways). A ‘chesty cough’ produces phlegm whereas a ‘dry cough’ is more of a tickle. Most coughs are caused by a virus and will get better by themselves. It is a good idea to rest, take painkillers and drink plenty of fluids. If you’ve had a cough for three weeks or more we call this a ‘chronic cough’ and recommend you see a doctor to rule out a possible more serious cause.

Coughs may be accompanied by other symptoms including runny nose, sore throat, shortness of breath, fever or chest pain. A chronic cough can leave you feeling tired and self-conscious, particularly if you are experiencing sudden uncontrolled bouts of coughing. In some cases, disrupted sleep or underlying conditions such as sleep apnoea may also contribute to ongoing symptoms.

Common Causes of a Persistent Cough

There are many reasons why you might develop a chronic cough. Some of the most common include:

• Postnasal drip: This occurs when mucus from your nose drips down your throat and irritates your windpipe and lungs, causing you to cough. Allergies, viruses or inflammation can all irritate nasal membranes and create runny mucus. Postnasal drip is particularly common at night when you lie down. Possible treatments include a nasal spray, decongestant or antihistamine.
• Asthma: This is where the muscles around the airways tighten and the lining of the airways swells, making it harder to breathe. Thick mucus exacerbates the problem and coughing occurs because your body is trying to clear the mucus and get air into the lungs. Asthma can be triggered by many different things including cold air, tobacco smoke, allergies, infections or exercise. If you have an asthma diagnosis, your doctor will normally recommend an inhaler to open up the airways and reduce inflammation.
• Gastroesophageal reflux disease (GERD): This occurs when the muscle around the lower part of your oesophagus becomes weak, allowing acid to move upwards from the stomach which can irritate your lungs and trigger coughing. If you have GERD you may have other symptoms as well, including heartburn and chest pain. Lifestyle changes are normally recommended – such as avoiding food and drink that increase acid reflux – and you may be given medication to slow the production of stomach acid.
• COPD (chronic obstructive pulmonary disease): This is actually a group of diseases, rather than a single condition, including emphysema and chronic bronchitis. With COPD it can be hard for the air to get in and out of your lungs and your body may produce an excess of mucus, causing you to cough. COPD is linked to smoking. Symptoms are controlled using inhalers or oral steroids.
• Other possible causes of chronic cough include rhinitis and sinusitis, chronic bronchitis, infections, bronchiectasis and upper-airway cough syndrome.

Diagnosing a chronic cough

To diagnose what is causing your chronic cough, your doctor will examine you and take a medical history. You may also be given blood tests, allergy screening, a CT scan or lung function test.  In some cases where abnormalities are found on imaging, further investigations such as Endobronchial Ultrasound (EBUS) may be used to obtain tissue samples and help confirm a diagnosis. Once the cause of your cough has been identified, the next step is to come up with a management plan for controlling your symptoms.

When Should a Persistent Cough Be Investigated Further?

While many coughs are caused by infections or irritation and improve within a few weeks, a cough that lasts longer than three weeks, keeps returning, or gradually worsens should be assessed further.

You should consider seeking medical advice if your cough is associated with:

• Recurrent chest infections
• Breathlessness
• Chest pain
• Unexplained weight loss
• Coughing up blood

Depending on clinical findings, investigations may include imaging such as chest X-ray or CT scan, breathing tests, or referral for specialist assessment. In selected cases, advanced diagnostic procedures may be considered to examine the airways more closely. Early evaluation helps clarify the cause and guide appropriate management.

In some cases, particularly in individuals with risk factors such as a history of smoking or relevant family history, a structured lung health screening (including imaging such as lung cancer screening) may be considered. This allows appropriate imaging and specialist review where clinically indicated.

If your cough persists beyond three weeks or is associated with symptoms such as breathlessness, chest pain, or weight loss, it is advisable to seek specialist assessment.

Are chronic coughs more common in winter?

Winter is a peak time for many different types of illnesses including chronic coughs. This is because colder weather can irritate the airways causing inflammation and triggering coughing. Also, because we tend to spend more time indoors during winter, infections can spread more easily and we are more likely to be exposed to viruses. Lower levels of vitamin D from sunlight may also increase our susceptibility.

If you have a persistent cough lasting more than three weeks, or symptoms that concern you, arranging a respiratory consultation can help clarify the cause and guide appropriate investigation and treatment.

When to Seek Specialist Advice for a Persistent Cough

If your cough lasts longer than three weeks, keeps returning, or is associated with symptoms such as breathlessness or chest pain, it may be helpful to seek specialist advice.

Assessment can help clarify the cause and guide appropriate investigations and treatment.