Press release

Green phlegm and snot ‘not always a sign of an infection needing antibiotics’

Advice on European Antibiotics Awareness Day (18 November 2014) to raise awareness of the risks of inappropriate use of antibiotics.


Having green phlegm or snot is not always a sign of a bacterial infection that will require antibiotics to get better, says Public Health England (PHE) and the Royal College of General Practitioners (RCGP).

This advice is issued on European Antibiotics Awareness Day (18 November) which aims to raise awareness of the risks associated with the inappropriate use of antibiotics and how to use them responsibly.

Research by PHE’s Primary Care Unit has found that 40% of the general public believed that antibiotics would help a cough with green phlegm get better more quickly rather than clear phlegm (6%).

White blood cells are produced by the body to attack any foreign materials the body does not recognise such as pollutants, dirt, pollen or microbes, and are carried in your phlegm and snot. Some white blood cells contain a green substance (a protein) so if more of these cells are present the greener your phlegm or snot will be.

Phlegm therefore comes in a range of colours from white to mustard-yellow to varying shades of green. Coloured phlegm or snot does not mean you need antibiotics.

In most healthy people, phlegm or snot production with or without a cough will stop as your cold or flu-like illness clears up, although it may take up to 3 to 4 weeks.

Dr Cliodna McNulty, head of PHE’s primary care unit said:

It’s a prevailing myth that anyone with green phlegm or snot needs a course of antibiotics to get better. Most of the infections that generate lots of phlegm and snot are viral illnesses and will get better on their own although you can expect to feel pretty poorly for a few weeks. There are plenty of over-the-counter medicines which are very effective in managing the symptoms of these illnesses and can reduce headache, muscle soreness, fever and sore throats.

The problems of antibiotic resistance are growing. Everyone can help by not using antibiotics for the treatment of uncomplicated infections. Any antibiotics we take will also kill many of our normal bacterial flora in the gut. Antibiotics also encourage other bacteria in our gut to develop resistance to antibiotics by changing their genetic makeup. These resistant bacteria can then in turn pass their resistance genes on to other bacteria, or they can be passed to other people we have close contact with. In the long run, this will mean our antibiotics become less effective, or in the worse case scenario, not effective at all.

Many people have a good understanding of what antibiotic resistance is but when it comes to their own illnesses still believe that antibiotics can help to treat what can be severe cold and flu symptoms. This is not the case and we must get away from believing this to preserve these precious medicines for when we really need them.

Dr Maureen Baker, Chair of the RCGP, said:

The statistics from Public Health England are not surprising. Many patients expect their GPs to prescribe antibiotics, even for cases that will get better naturally or respond better to other treatments.

This guidance will go a long way to bust the myths surrounding antibiotics and promote more effective alternatives, which can often be easily managed by patients.

Overuse of antibiotics is a serious public health concern and a clinical priority for the RCGP. Infections adapt to antibiotics used to kill them and can ultimately make treatment ineffective so it’s crucial that antibiotics are used appropriately. That’s why we have recently updated our comprehensive TARGET toolkit, developed in collaboration with PHE, to include new guidance for GPs and their patients on the appropriate prescription of antibiotics so that they do not build up an immunity for the future when they might really need them.


Who doesn’t usually need antibiotics when they have coughs with or without phlegm?

  • In otherwise healthy non-smoking individuals who have no underlying health problems, having an acute cough with phlegm of any colour is not necessarily a sign of infection and any small possible benefit from antibiotics is likely to be outweighed by the side effects.
  • If you are a smoker with no diagnosis of chronic obstructive pulmonary disease (COPD) then you are not in any greater need of antibiotics than non smokers.
  • If you are an adult or a child with asthma and have a cough with phlegm you do not need antibiotics to get better but you may need extra asthma treatment.

Who may need antibiotics if they have a cough with or without phlegm?

  • If you have chronic obstructive pulmonary disease (COPD) with green phlegm you should see your doctor as you may have an infection. People with COPD are more likely to be/have been smokers and green phlegm in this group is more indicative of a sign of infection.
  • If you have had a recurrent chest infections you should also see your doctor for a clinical review as you may have an infection.
  • Those who are older (over 65) or who have other chronic lung and heart conditions may need to seek advice about treatment.

Who should go to the doctors more urgently?

  • If you have difficulty breathing, breathing quickly, have chest pain or are coughing up blood, or feeling confused or are very drowsy.

What can patients do to get better with coughs– now and in the future?

  • Try not to cough: although this may sound easier said than done, you may be able to cough less often by trying not to cough, because our desire to cough can sometimes be influenced by our brain.
  • Home remedies: try simple home remedies, such as ‘honey and lemon’ – just add freshly squeezed juice from 1 lemon and a teaspoon of honey to a mug of hot water. Drink enough fluids to avoid feeling thirsty and suck lozenges.
  • Stop smoking: smoking is one of the commonest reasons for a chronic cough. Stopping smoking – or at least smoking less – not only improves your cough, but also benefits your health in other ways (reducing the risk of heart attack, stroke, and lung cancer, for example).
  • Cough mixtures: there is little evidence to say whether over the counter medicines are effective for relieving cough symptoms. Despite the lack of research evidence, you may still get some subjective benefit from over the counter preparations – speak to your pharmacist.
  • Paracetamol: paracetamol can help relieve symptoms that may accompany a cough, such as a sore throat, fevers, and not feeling well.

PHE are encouraging GP staff to discuss the need for antibiotics with their patients using an antibiotic information leaflet available on the TARGET antibiotics website.

See Earl Howe’s statement supporting European Antibiotic Awareness Day on the Self Care Forum website.

More information about European Antibiotic Awareness Day, or EAAD

The data on public attitudes to antibiotics is available from the Journal of Primary Care

Materials for GP staff to share with patients is available on the RCGP website, including an antibiotic information leaflet and a list indicating when patients should call their doctor or contact NHS 111.

The following symptoms appear in order of urgency, with the most urgent symptoms listed first. If you develop these symptoms, call your GP or contact NHS 111:

  • if you develop a severe headache or are sick
  • if your skin is very cold or has a strange colour, or you develop an unusual rash
  • if you feel confused or have slurred speech or are very drowsy
  • if you have difficulty breathing. Signs that suggest breathing problems can include:
    • breathing quickly
    • turning blue around the lips and the skin below the mouth
    • skin between or above the ribs getting sucked or pulled in with every breath
  • if you develop chest pain
  • if you have difficulty swallowing or are drooling
  • if you cough up blood
  • if hearing problems develop or if there is fluid coming out of your ears

Public Health England’s mission is to protect and improve the nation’s health and to address inequalities through working with national and local government, the NHS, industry and the voluntary and community sector. PHE is an operationally autonomous executive agency of the Department of Health. Follow us on Twitter @PHE_uk

The Royal College of General Practitioners is a network of more than 46,000 family doctors working to improve care for patients. We work to encourage and maintain the highest standards of general medical practice and act as the voice of GPs on education, training, research and clinical standards.

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Published 18 November 2013
Last updated 18 November 2013 + show all updates
  1. Added link to Self Care Forum in the notes to editors.

  2. First published.