Chronic cough: causes, treatment and when to see a doctor

A cough is a reflex that clears your airways of phlegm and irritants such as dust or smoke. NICE CKS describes it as a reflex response to airway irritation, triggered when cough receptors in the airways are stimulated. Most coughs are short-lived: the NHS says a cough will usually clear up on its own within 3 to 4 weeks, and most are caused by a cold or flu.

A chronic cough is one that carries on. NICE CKS uses a simple three-way split by duration, shown in the table. NHS inform uses the word "persistent" for a cough that goes on beyond 3 weeks and advises speaking to your GP practice at that point.

There is no single treatment, because chronic cough is a symptom with several possible causes. NICE CKS says management is based on treating the underlying cause when it has been identified, or on sequential trials of treatment to confirm or rule out the common causes in turn. That is why a doctor may suggest one treatment for a few weeks, review it, and then try another.

NHS inform gives examples of treating the cause. The table pairs these with the treatment groups named in NICE CKS prescribing information (proton pump inhibitors, nasal corticosteroids, beta-2 agonists and inhaled corticosteroids). Which, if any, applies to you depends on what your clinician finds.

NICE CKS advises referral to a respiratory physician if the cough does not respond to a trial of treatment, or if the diagnosis is uncertain. If the cough persists after the usual causes have been treated, the guide to refractory chronic cough covers that situation.

NICE CKS names six most common causes of chronic cough, listed below. NHS inform adds bronchiectasis (where the airways of the lungs become abnormally widened) and allergy to its list of causes of a persistent cough, and points out that often the cause of a persistent cough is unknown (idiopathic).

• Smoking. NHS inform says a smoker's cough can also be a symptom of COPD.

• Angiotensin-converting enzyme (ACE) inhibitors, a group of blood pressure and heart medicines.

• Upper airway cough syndrome, previously called post-nasal drip, where mucus drips down the throat from the back of the nose.

• Asthma, which NHS inform says usually causes other symptoms too, such as wheezing, chest tightness and shortness of breath.

• Gastro-oesophageal reflux disease (GORD), where the throat becomes irritated by stomach acid.

• Eosinophilic bronchitis, an airway inflammation named in NICE CKS.

NHS inform lists ACE inhibitors, with ramipril and lisinopril as examples, among the prescribed medicines that can cause a persistent cough. The NHS medicine page for ramipril says a dry, persistent cough that does not get better is a common side effect, affecting more than 1 in 100 people, and that cough medicines do not usually help.

The NHS adds that sometimes the cough gets better on its own if you keep taking ramipril, and that you should talk to your doctor if it carries on, bothers you or stops you sleeping, as another medicine may be better. Do not stop a blood pressure or heart medicine on your own; ask your GP or pharmacist first.

NHS inform describes a dry cough as tickly, without mucus (phlegm), and a chesty cough as one that produces phlegm to help clear the airways. Which type you have, and what comes with it, helps point to the cause.

NHS inform says that in most cases a doctor will want to know if you are producing much more or darker phlegm than usual, so it helps to note this before your appointment. A symptom diary covering what sets the cough off, when it is worst and what you take for it is also useful.

• Wheezing, chest tightness or breathlessness alongside the cough can point towards asthma (NHS inform).

• Heartburn or other acid reflux symptoms alongside the cough can point towards GORD, which NHS inform describes as the throat becoming irritated by stomach acid.

• Mucus running down the back of the throat can point towards upper airway cough syndrome (NICE CKS).

• A dry, persistent cough that began after starting blood pressure tablets can point towards an ACE inhibitor (NHS).

• Coughing with weight loss, tiredness or coughed-up blood needs prompt assessment (NHS).

The NHS says the GP might listen to your chest with a stethoscope, take a sample of any mucus you cough up, and order an X-ray, an allergy test or a test of how well your lungs work. Referral to hospital to see a specialist is described as rare.

NICE CKS says the cause may be determined by history, examination and investigation where appropriate, and that spirometry and a chest X-ray are advised for a chronic cough of uncertain cause. A peak expiratory flow rate is used if asthma is known or suspected. NHS inform adds breathing tests and analysis of a phlegm sample to check for infection to the list.

Expect questions about smoking, the medicines you take, your work and any heartburn or nasal symptoms. Our guide to the diagnosis of chronic cough walks through the investigations in more detail.

NHS inform says coughs in children can also be caused by respiratory tract infections, asthma or GORD. Causes more common in children than adults include bronchiolitis, croup (a distinctive barking cough with a harsh sound called stridor on breathing in) and whooping cough (intense, hacking bouts of coughing, sometimes with vomiting and a "whoop" sound).

NHS inform says occasionally a persistent cough in a child can be a sign of a serious long-term condition such as cystic fibrosis. A child with a cough that lasts for weeks, or who has difficulty breathing, should be seen by a GP. NHS inform also says over-the-counter cough and cold medicines should not be given to children under 6, and that children aged 6 to 12 should only use them on the advice of a pharmacist or doctor. Honey should not be given to babies under 1.

The NHS suggests resting, drinking plenty of fluids and, if you have a high temperature or feel unwell, staying at home and avoiding contact with other people. Paracetamol or ibuprofen can ease pain, and a hot lemon and honey drink may be soothing, although the NHS says there is limited evidence that it or herbal medicines help.

A pharmacist can advise about cough syrups, medicines and sweets. The NHS says these will not stop your cough but may help you cough less, and that decongestants and cough medicines containing codeine will not stop it. If you smoke, NHS inform says quitting is likely to help improve your cough.

The NHS advises seeing a GP if you have had a cough for more than 3 weeks, are losing weight for no reason or have a weakened immune system, for example because of chemotherapy or diabetes. The sources set out the urgent signs below.

• Call 999 or go to A&E if you have severe difficulty breathing, severe chest pain that is not going away, pain spreading to your arms, back, neck or jaw, are more drowsy than usual, or your lips or skin turn very pale, blue or grey (NHS inform).

• Ask for an urgent GP appointment or get help from NHS 111 if you are coughing up blood, feel very unwell, have chest pain, find it hard to breathe, your cough is very bad or quickly gets worse, or the side of your neck is swollen and painful (NHS).

• Contact your GP practice urgently if you are more short of breath than usual, have pain when breathing in or coughing, feel confused or dizzy, or have a very high or low temperature (NHS inform).

• NICE CKS advises emergency admission for people with a suspected pulmonary embolism or pneumothorax, or clinical features of a swallowed object in the airway.

Usually not. The NHS says a cough is rarely a sign of something serious like lung cancer. Even so, the NHS lists "a cough that is not going away" among the common symptoms of lung cancer, together with shortness of breath, coughing up blood, chest or shoulder pain, repeated chest infections, weight loss without trying, loss of appetite and tiredness.

The NHS says to see a GP if you have had a cough for longer than 3 weeks or have any other symptoms of lung cancer, and that an urgent referral for tests does not definitely mean you have cancer. NHS inform also names heart failure, a blood clot on the lung and tuberculosis as rare causes of a persistent cough.

On the NHS, the first step is your GP practice, who can arrange a chest X-ray and breathing tests and may try treatments for the likely cause in turn. If a cough does not respond or the diagnosis is uncertain, NICE CKS advises referral to a respiratory physician. A pharmacist can advise on cough treatments without an appointment.

Some people choose to see a private respiratory physician or have scans privately to move faster. The assessment, tests and treatment trials are the same in either setting; ask that results are sent to your GP so your record stays complete.