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Cough

What is a cough?

A cough is a reflex action to clear your airways of mucus and irritants such as dust or smoke. It’s rarely a sign of anything serious.

A “dry cough” means it’s tickly and doesn’t produce any phlegm (thick mucus). A “chesty cough” means phlegm is produced to help clear your airways.

Most coughs clear up within three weeks and don’t require any treatment. For more persistent coughs, it’s a good idea to see your GP so they can investigate the cause.

What can cause a cough?

Some of the main causes of short-term (acute) and persistent (chronic) coughs are outlined below.

Short-term coughs

Common causes of a short-term cough include:

  • an upper respiratory tract infection (URTI) that affects the throat, windpipe or sinuses – examples are a cold, flu, laryngitis, sinusitis or whooping cough
  • a lower respiratory tract infection (LRTI) that affects your lungs or lower airways – examples are acute bronchitis or pneumonia
  • an allergy, such as allergic rhinitis or hay fever
  • a flare-up of a long-term condition such as asthma, chronic obstructive pulmonary disease (COPD) or chronic bronchitis
  • inhaled dust or smoke

In rare cases, a short-term cough may be the first sign of a health condition that causes a persistent cough.

Persistent coughs

A persistent cough may be caused by:

  • a long-term respiratory tract infection, such as chronic bronchitis
  • asthma – this also usually causes other symptoms, such as wheezing, chest tightness and shortness of breath
  • an allergy
  • smoking – a smoker’s cough can also be a symptom of COPD
  • bronchiectasis – where the airways of the lungs become abnormally widened
  • postnasal drip – mucus dripping down the throat from the back of the nose, caused by a condition such as rhinitis or sinusitis
  • gastro-oesophageal reflux disease (GORD) – where the throat becomes irritated by leaking stomach acid
  • a prescribed medicine, such as an angiotensin-converting enzyme inhibitor (ACE inhibitor), which is used to treat high blood pressure and cardiovascular disease

In most cases, a doctor won’t worry whether a cough is dry or chesty, but will need to know if you are producing much more or darker phlegm than usual.

Rarely, a persistent cough can be a symptom of a more serious condition, such as lung cancer, heart failure, a pulmonary embolism (blood clot on the lung) or tuberculosis.

When should I seek medical advice?

There’s usually no need to see a doctor if you have a cough for a week or two. However, you should seek medical advice if:

  • you’ve had a cough for more than three weeks
  • your cough is particularly severe
  • you cough up blood or experience shortness of breath, breathing difficulties or chest pain
  • you have any other worrying symptoms, such as unexplained weight loss, a persistent change in your voice, or lumps or swellings in your neck

If your doctor is unsure what’s causing your cough, they may refer you to have some tests, such as a chest X-ray, allergy tests, breathing tests, and an analysis of a sample of your phlegm to check for infection.

Treating a cough

Treatment isn’t always necessary for short-term coughs because it’s likely to be a viral infection that will get better on its own within a few weeks. You can look after yourself at home by resting, drinking plenty of fluids, and taking painkillers such as paracetamol or ibuprofen.

Cough medicines and remedies

Although some people find them helpful, medicines that claim to suppress your cough or stop you bringing up phlegm are not usually recommended. This is because there’s little evidence to suggest they’re any better than simple home remedies, and they’re not suitable for everyone.

A homemade remedy containing honey and lemon is likely to be just as useful and safer to take.

Treating the underlying cause

If your cough has a specific cause, treating this may help. For example:

  • asthma can be treated with inhaled steroids to reduce inflammation in your airways
  • allergies can be treated by avoiding things you’re allergic to and taking antihistamines to dampen down your allergic reactions
  • bacterial infections can be treated with antibiotics
  • GORD can be treated with antacids to neutralise your stomach acid and medication to reduce the amount of acid your stomach produces
  • COPD can be treated with bronchodilators to widen your airways
  • If you smoke, quitting is also likely to help improve your cough