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Encyclopaedia


Cough

Introduction

A cough is a reflex action to clear your airways of mucus and irritants such as dust or smoke.

Coughs may be dry or chesty (see below). They're also classified according to how long they last:

  • acute cough lasts for less than three weeks
  • subacute cough gets better over a three-to-eight-week period
  • chronic (persistent) cough lasts for longer than eight weeks

Coughs caused by the common cold or by flu usually clear up after several days. Most coughs clear up within two weeks.

For more information on treating cough, go to Treatment.

What are the causes?

Most people with a cough have a respiratory tract infection caused by a virus, such as the common cold, flu or bronchitis.

A persistent cough in adults may be caused by a condition such as rhinitis, or by a prescribed medicine such as an angiotensin-converting enzyme (ACE)-inhibitor, which is used to treat high blood pressure or cardiovascular disease, or by smoking.

In children, a persistent cough may indicate a more serious respiratory tract infection such as whooping cough.

For more information on conditions that cause cough, go to Causes of cough.

When to see your doctor

See your GP if you've had a cough for more than two weeks after a viral infection, or if your cough is progressively getting worse.

Dry cough versus chesty cough

Dry cough

Dry coughs are usually felt in the throat as a tickle that sets off the coughing.

It happens when the throat and upper airways become inflamed (swollen). It is non-productive, which means that phlegm (thick mucus) isn't produced.

The common cold or flu causes a dry cough because your brain thinks the inflammation in your throat and upper airways is a foreign object and tries to remove it by coughing.

Chesty cough

A chesty cough usually produces phlegm. The cough is helpful, because it clears the phlegm from your lung passages.

If you or someone you know is suffering with a cough, you can use our online Cough Symptom Checker to find out what to do.

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Symptoms

How long a cough lasts for depends on the cause. If it has been caused by the common cold, it can clear up after two to three days. Most coughs clear up within two weeks.

A dry cough will feel like a constant tickle in your throat. When you cough, there won't be any phlegm (thick mucus).

If you have a chesty cough as a result of a respiratory infection, you may cough up phlegm.

If you have a cough due to a viral infection, such as flu or bronchitis, you won't usually need to see a doctor unless your symptoms are severe.

When to see your doctor

See your GP if your cough has lasted for more than two weeks or is getting progressively worse.

Occasionally, a secondary bacterial infection occurs, which can lead to a more serious condition developing, such as pneumonia.

Typical symptoms of pneumonia include rapid and shallow breathing, wheezing and coughing up phlegm that may be yellow, green, brownish or blood-stained.

'Red flag' signs in children

The following may indicate a serious condition:

  • a cough that occurs with feeding
  • a cough that is persistent with phlegm
  • a cough that is associated with night sweats or weight loss
  • a cough that isn't getting better or is getting worse

Symptoms of whooping cough

Symptoms of whooping cough may include:

  • intense, hacking bouts of coughing, which bring up thick phlegm
  • a 'whoop' sound with each sharp intake of breath after coughing
  • vomiting in infants and young children
  • fatigue and redness in the face from the effort of coughing

For more information, go to A-Z: whooping cough

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Causes

Most coughs are caused by viral infections and usually clear up on their own.

Acute cough

Most people with an acute cough have a respiratory tract infection caused by a virus.

It will usually be an upper respiratory tract infection (URTI), which means the virus has affected your throat or windpipe. Examples of URTIs causing cough are:

If your cough is caused by a lower respiratory tract infection (LRTI), the virus has infected your airways lower down, or your lungs. Examples of LRTIs are:

Other possible causes for an acute cough are allergic rhinitis, such as hay fever. In rare cases it may be the first sign of a chronic disease (see below).

Chronic cough

Common causes of a persistent cough in adults are:

Some prescribed medicines can also cause a persistent cough (for example, angiotensin-converting enzyme [ACE]-inhibitors, which are medicines for treating high blood pressure or cardiovascular disease).

In children, common causes are:

  • respiratory tract infections, such as bronchitis or whooping cough 
  • gastro-oesophageal reflux disease

Rarely, a cough is a symptom of a more serious condition such as lung cancer, heart failure, a pulmonary embolism (clot on the lung), cystic fibrosis or tuberculosis (TB).

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Diagnosis

Coughs caused by the common cold or by flu usually clear up after a few days, so you will not have to see your GP.

If you have had a cough for more than two weeks following a viral infection, seek medical advice from your GP.

Your GP will take your medical history and do a full clinical examination, and sometimes take some tests.

Tests

Your GP may do a chest X-ray to see if you have a chest infection and, if there is an infection, to determine the extent of this.

If you have a chesty cough, a sample of your coughed-up phlegm may be taken for analysis in a laboratory, to determine which germ has caused the infection. This information can then be used to decide whether or not antibiotics should be used to treat it (see Treatment).

Spirometry may be used to see if you have an underlying respiratory condition. It involves breathing in and out of a tube connected to a machine, so that your GP can assess whether or not your airways have narrowed.

If your GP thinks you may have asthma, you may be prescribed asthma medication for a trial period, to see if this helps.

You may have allergy testing, such as a skin prick test, to see if your cough is caused by something you are allergic to, such as house dust mites.

Referral

If your GP is unsure what is causing your cough or your cough is getting worse, they may refer you to a respiratory specialist.

If your child has inhaled something...

If you think your child is coughing because they have inhaled an object, see your GP straight away.

They may need to be referred for an urgent bronchoscopy (test that views the airways).

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Treatment

There's no quick way of getting rid of a cough that's caused by a viral infection. It will usually clear up after your immune system has fought off the virus.

The simplest and cheapest way to treat a short-term cough may be a homemade cough remedy containing honey and lemon. The honey is a demulcent, which means it coats the throat and relieves the irritation that causes coughing.

Cough medicines

There's little evidence to suggest that cough medicines actually work, although some of the ingredients may help to treat symptoms that are associated with a cough, such as a blocked nose or fever.

Some contain paracetamol, so don't take more than the recommended dosage. Cough medicines should never be taken for more than two weeks.

They can be used for any type of cough and are generally safe, but diabetics should note that they're usually sugar-based.

Treating children

The Medicines and Healthcare products Regulatory Agency (MHRA) has recommended that over-the-counter cough and cold medicines shouldn't be given to children under the age of six.

The MHRA is the government body responsible for ensuring that medicines are safe and effective.

The agency has made this recommendation because it feels there's a potential risk of these medicines causing unpleasant side effects, such as allergic reactions, sleep problems or hallucinations (seeing and hearing things that aren't real). These would outweigh any benefit provided by the medicines.

Instead, give your child a warm drink of lemon and honey or a simple cough syrup that contains glycerol or honey.

However, honey shouldn't be given to babies under the age of one, due to the risk of infant botulism.

Cough suppressants

Cough suppressants, such as pholcodine, dextromethorphan and antihistamines, act on the brain to hold back the cough reflex. They're used for dry coughs only.

  • Pholcodine and dextromethorphan have few side effects or interactions with other medicines.
  • Antihistamines sometimes cause drowsiness, which can be helpful if your cough is disrupting your sleep. Other possible side effects are a dry mouth, constipation, difficulty in passing urine and blurred vision. Antihistamines might interact with other medicines, such as antidepressants and those that cause drowsiness.

Check with your GP or pharmacist before taking cough suppressants.

Expectorants

Expectorants help bring phlegm up so that coughing is easier, which may help chesty coughs. They include:

  • guaiphenesin
  • ammonium chloride
  • squill
  • sodium citrate
  • ipecacuanha

These compounds are all found in small quantities in cough mixtures, so they're unlikely to have any side effects or interact with other medicines.

Antibiotics

Antibiotics are not used to treat coughs because they are only effective in killing bacteria, not viruses. Therefore, unless you develop a secondary bacterial infection, such as pneumonia, antibiotics will not usually be advised.

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Q&A

Can I take cough and cold remedies while I'm breastfeeding?

Cough and cold remedies are generally not recommended while you’re breastfeeding.

Most colds will get better on their own. You can often relieve symptoms with simple measures, such as:

  • rest
  • drinking plenty of fluids
  • inhaling steam
  • taking over-the-counter (OTC) medicines, such as paracetamol or ibuprofen

If you’re breastfeeding, it may be better to try measures like these rather than taking cough and cold remedies. 

Medicines while you’re breastfeeding

Many illnesses can be treated with medicines while you’re breastfeeding without harming your baby. However, small amounts of the medicine will pass through your breast milk to your baby, so always tell your GP or pharmacist that you’re breastfeeding.

You should seek further advice from your GP before taking medicines if your baby was born early (prematurely), had a low birth weight or has a medical condition.

Ingredients in cough and cold remedies

If you’re thinking about taking a combined cough or cold remedy, read the patient information that comes with the medicine to see what ingredients it contains. Products sold to treat coughs and colds usually contain several ingredients, and some may not be safe to take while you’re breastfeeding. You need to consider each ingredient separately to decide whether the remedy is safe.

Always follow the recommended dosage instructions. For example, some remedies may also contain paracetamol. When taken in addition to regular paracetamol, this can mean you exceed the recommended dose. 

The following medicines should not be taken while you’re breastfeeding, either on their own or in any medicines that contain them:

  • aspirin: a painkiller 
  • codeine: a painkiller 
  • phenylephrine: a decongestant (for blocked noses) found in some cold medicines 
  • phenylpropanolamine: a decongestant found in some cold medicines
  • guaifenesin: an expectorant (to bring up phlegm) found in some cough medicines 
  • any ingredient that produces drowsiness: such as some antihistamines that may be found in decongestants - for example, diphenhydramine

Cough medicines

The simplest, cheapest way to treat a short-term cough may be with a cough remedy made at home from hot water, honey and lemon juice. The honey is a demulcent, which means it coats the throat and relieves the irritation that causes coughing.

A simple linctus (a sugary, liquid solution based around lemon and glycerine) is also usually safe to take to soothe coughs. A sugar-free linctus may also be available.

Check the ingredients in any branded linctus as some may contain other ingredients that aren’t safe to take while you’re breastfeeding.

Cold remedies

Cold medicines are widely used but there is little evidence that they are effective in curing a cold, although some may relieve symptoms. 

Getting advice 

To find out more about your medicine, check the patient information leaflet that comes with it or read the information on the packet.

If you have any concerns, or need help understanding the information and relating it to your own situation, you can:

  • talk to your midwife, health visitor, GP or pharmacist
  • see the drugs in breast milk factsheets from the Breastfeeding Network
  • call the drugs in breast milk helpline on 0844 412 4665
  • call NHS Direct Wales on 0845 4647
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The information on this page has been adapted by NHS Wales from original content supplied by NHS Choices.
Last Updated: 03/12/2014 09:49:10

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