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Viral cough

Cough caused by a virus

Most coughs are caused by viral infections and usually soon go. This leaflet gives some tips on what to do and discusses which symptoms may indicate a more serious illness.

Viral infections commonly affect the throat (larynx), the main airway (trachea), or the airways going into the lungs (bronchi). These infections are sometimes called laryngitis, tracheitis, or bronchitis. Cough is often the main symptom.

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How can I tell if my cough is viral or bacterial?

This may not be easy in the early stages as cough is a common symptom of both viral and bacterial infections.

A viral infection of the upper respiratory system (in other words a common cold) often causes nasal symptoms such as a stuffy nose and sneezing which usually clear up after a few days. Though the cough may persist for up to four weeks, you generally start to feel better as the days go by.

If you start to feel worse, this is one sign that you may have a bacterial infection. Other features suggesting that you may be developing a bacterial infection are a fever above 38°C and coughing up thick discoloured phlegm. You may develop chest pain, rapid breathing, and/or rapid pulse. Wheezing and difficulty in breathing may be other signs.

Viral cough symptoms

The cough typically develops over a day or so and may become quite irritating. Other common symptoms may develop and include:

Cold symptoms may occur if the infection also affects the nose. Symptoms typically peak after 2-3 days, and then gradually clear. However, the cough may persist for a few weeks after the infection has gone. This is because the inflammation in the airways, caused by the infection, can take a while to clear.

Cough caused by COVID-19 infection

COVID-19 should also still be considered as an important cause of cough.

Apart from a new continuous cough, other symptoms may include:

  • A high temperature.

  • A loss or change to your sense of taste or smell.

See our separate editorial content called Coronavirus: what are asymptomatic and mild COVID-19? and Coronavirus: what are moderate, severe and critical COVID-19? for more details.

The rest of this leaflet is about coughs which are not caused by the coronavirus.

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How long will I remain infectious?

If you have a viral infection like a common cold, you can pass it on to other people for as long as your symptoms persist. You are most infectious in the first two days. Most people are clear of infection after about two weeks.

Viral cough treatment

There is no 'quick fix' for a cough due to a viral infection. You need to be patient until the cough goes. A main aim of treatment is to ease symptoms whilst your immune system clears the infection. The most useful treatments are:

  • Taking paracetamol, ibuprofen, or aspirin to reduce high temperature (fever), and to ease any aches, pains and headaches. (NB Children aged under 16 years should not take aspirin.)

  • Having lots to drink if you have a fever, to prevent lack of fluid in the body (dehydration).

  • Stopping smoking. If you smoke, you should try to stop for good. A cough and serious lung diseases are more common in smokers.

What about cold and cough remedies?

You can buy many other cold and cough remedies at pharmacies. There is little evidence of any impact on the infection but they may be useful for certain symptoms. For example, a decongestant nasal spray, used for less than seven days, may help to clear a blocked nose.

But remember, cold and cough remedies often contain several ingredients. Some may make you drowsy. This may be welcome at bedtime if you have difficulty sleeping with a cough.

However, do not drive if you are drowsy. Some contain paracetamol, so be careful not to take more than the maximum safe dose of paracetamol if you are already taking paracetamol tablets.

Note: Cough and cold medicines and decongestants that are available over-the-counter should not be given to children under 6 years old. However, paracetamol and ibuprofen can still be used.

What about antibiotic medicines?

Antibiotics are not usually advised. Antibiotics do not kill viruses - they only kill germs called bacteria. Antibiotics do not ease a cough caused by a virus. They may even make symptoms worse, as they sometimes cause side-effects such as loose or watery stools (diarrhoea), feeling sick and rashes.

Antibiotics may be prescribed if you already have an ongoing (chronic) lung disease. This is to prevent a 'secondary' bacterial infection rather than to clear a viral infection.

Antibiotics may also be prescribed if a complication develops such as secondary bacterial pneumonia - but this is unlikely to occur if you are otherwise healthy.

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Viral cough complications

Most viral coughs clear without complications. However, sometimes a 'secondary' infection with germs (bacteria) develops in addition to the viral infection. This may become serious and cause pneumonia.

Also, other causes of cough (such as asthma) are sometimes confused with a viral infection. So see a doctor if any of the following occur:

  • If you develop symptoms of a possible bacterial infection, as described above.

  • If you cough up blood. Blood may be bright red but dark or rusty-coloured sputum may indicate blood.

  • If you become drowsy or confused.

  • If you develop any symptoms which you are unhappy about, or do not understand.

  • If you have a cough that persists for longer than 3-4 weeks.

Viral cough prevention

Prevention of a viral cough is very difficult. Many of the viruses that cause coughs and colds are present in the air, particularly in the winter months. However, good hygiene may reduce the risk of you getting and passing on viruses that can cause a cough:

  • If you have a cough, runny nose or fever, avoid close contact with other people if feasibly possible (hugging, kissing, regular touching)

  • Wash your hands often with soap and water, particularly if you have a viral cough.

  • Avoid sharing towels and cutlery if you have viral symptoms.

Further reading and references

Article history

The information on this page is written and peer reviewed by qualified clinicians.

  • Next review due: 7 Jan 2029
  • 9 Jan 2024 | Latest version

    Last updated by

    Dr Surangi Mendis

    Peer reviewed by

    Dr Colin Tidy, MRCGP
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