Does Green Phlegm Mean Infection?

  • Anna Mizerska Masters in Global Health and Biomedical Engineer, Norwegian University of Science and Technology (NTNU), Norway
  • Maura Mary Joseph Spanish and German with a year Abroad, Spanish, University of York, UK

Coughing up phlegm can be an indicator that your airways are inflamed. You can distinguish one kind of phlegm from another by the colour. According to Public Health England (PHE) and the Royal College of General Practitioners (RCGP), the presence of green nasal discharge or phlegm doesn't necessarily indicate a bacterial infection requiring antibiotics for recovery.2 White blood cells are produced by your body to attack any unfamiliar materials the body does not know, such as pollen, dirt, pollutants or microbes, and are carried in your snot or phlegm. Some white blood cells consist of green material (a protein), so if more of these cells are present, the greener your snot or phlegm will be. Thus, phlegm comes in a range of colours, from white to mustard-yellow to varying tones of green. Coloured snot phlegm does not mean you need antibiotics. In most athletic people, snot or phlegm production without or with a cough will stop as your flu-like sickness or cold clears up, although it may take up to 3 to 4 weeks.1

What is phlegm?

Phlegm is the unique name for mucus that you cough up from your lungs. Your doctor might call it ‘sputum’. is a jelly-like liquid found all over your body that defends you from infection. Similar to mucus, phlegm is a natural bodily secretion primarily composed of water, proteins, and inorganic salts. It tends to be thicker than mucus, even though it serves the same function.1,3

Colours of phlegm

There are a lot of misinterpretations about the meaning of phlegm colour. In the first place, the medical term for phlegm and mucus that has been coughed up or discarded through the nose is sputum. Sputum can range from clear to fluctuating shades of yellow, brown, red or green. When you are sick with the flu, cold or infection, your body dispatches white blood cells (neutrophils) to patch up the damage. These cells possess green enzymes that impact the colour of your mucus (sputum). The higher the number of white blood cells, the more green the sputum becomes. Contrary to the popular concept, phlegm colour does not necessarily indicate an infection. It just means your body is working harder to repair the problem.3

Green phlegm: what does it mean?

When your phlegm or mucus is green, it mainly indicates a respiratory infection. What kind of respiratory infection? It can’t necessarily be recognized just by the presence of green phlegm when sneezing or coughing.

Roots of green phlegm can consist of:

Sinusitis - also known as inflammation of the sinuses. Sinusitis can be caused by a number of viruses, bacteria, and allergens or airborne irritants.

Bronchitis - while this airway disease typically starts with a dry cough, it can progress into a cough that creates clear or white phlegm, then progressively turn into coughing up green phlegm if there is a developing infection (which may be changing from viral to bacterial in nature).

Pneumonia - fungal, viral, and bacterial types of pneumonia, all of which typically develop from a previously existing reportorial condition.

Cystic fibrosis - the trademark of this chronic respiratory condition is the accumulation of mucus in the lungs. Phlegm from cystic fibrosis can be a variety of colours, including dark green.

You may notice the texture or colour of your phlegm changing over the time of your illness. As your immune system continues to combat the infection in your respiratory system, your phlegm may become thicker and darker green. This darkening and thickening can also be an indicator of dehydration and a sign that you need to intake more fluids.4

The effects of green phlegm

When you have phlegm of any kind in your respiratory system, it can cause a fair amount of discomfort and disruption to your daily routine. You need to focus your treatment on minimizing the discomforting symptoms associated with whatever illness is causing you to cough up green phlegm.4

When should you determine if there is an infection?

If you feel unwell and you are worried because your phlegm is a different colour or thickness than usual, speak to your doctor. They may examine or analyze a sample of your phlegm to gather further information and determine the type of infection you are experiencing.1 It is a current myth that anyone with green snot or phlegm needs a course of antibiotics to get better. The majority of infections that result in excessive mucus and phlegm production are viral in nature and typically resolve on their own. However, it's common to experience significant discomfort for several weeks. Numerous over-the-counter medications are highly efficient in alleviating the symptoms of these illnesses, helping to alleviate headaches, muscle discomfort, fever, and sore throats.2

Treatment and home remedies

If you are curious about how to get mucus out of your nose or how to get rid of phlegm in the throat, here are some help and solutions:

Expectorants - these are the most successful at getting rid of phlegm in the throat. These medications help to reduce the thickness of mucus and phlegm, facilitating easier expulsion from the body. The main element to look for is guaifenesin, which will help get the phlegm up and out.

Decongestants—These come in pills, syrups, and sprays. They decrease inflammation in nasal passageways, clear nasal blockage, and reduce mucus production. The best time to take decongestants is when you have a cold with a stifling nose.

Antihistamines - If your phlegm is triggered by an allergic reaction, these medications will inhibit the release of histamines, which induce swelling in nasal tissues, resulting in a runny nose. 

Natural Irrigation - what do your nasal passageways and farming have in common? Natural irrigation. This works by spraying a saline solution mixed with sterile water up your nose and through your nasal passageways, effectively rinsing them out.3

Home remedies: Keep hydrated and continue to eat - Hydration is essential in helping thin the phlegm in your airway and keep your immune system in fighting condition. Eating healthy is also key to getting over the breathing infection.

Use a humidifier - keeping your breathing system hydrated by way of ambient humidity is just as important for easing symptoms as remembering to drink plenty of water and other hydrating fluids.

Try known home remedies - Applying eucalyptus oils or poultices or gargling with salt water on your chest can help loosen phlegm and ease throat irritation.

Rest - it is simple but also true. Your body needs suitable rest to fight off an infection; do not push yourself to return to your day-to-day routine too quickly, or you may prolong the healing process.4

When to seek medical attention?

When Should You Worry About Green Phlegm? Call your doctor if your cough doesn't go away after a few weeks or if it also involves any one of these:

  • Coughing up thick, greenish-yellow phlegm
  • Wheezing
  • Experiencing a fever
  • Experiencing shortness of breath
  • Experiencing fainting
  • Experiencing ankle swelling or weight loss.4


When your mucus or phlegm is green, all signs point to a respiratory infection, but it can’t be necessarily discerned what kind of infection just by the presence of green phlegm when coughing or sneezing. Essentially, if you are coughing up green phlegm and have not been once diagnosed with a recurring respiratory condition (such as asthma or chronic obstructive pulmonary disorder - also known as COPD), there is a very good possibility that it will be self-limiting. Bacterial infections typically resolve in two weeks or less; viral infections may last up to three weeks. Contrary to popular belief, mucus colour does not necessarily signify an infection. It just signifies that your body is working harder to fix the problem.4


  1. Asthma + Lung UK. Phlegm, mucus and asthma. Asthma + Lung UK. 2020.
  2. Green phlegm and snot ‘not always a sign of an infection needing antibiotics’. GOV.UK. 2013.
  3. Buckleys. What is mucus and phlegm.
  4. Robitussin. Green phlegm: What you need to know. Robitussin.
This content is purely informational and isn’t medical guidance. It shouldn’t replace professional medical counsel. Always consult your physician regarding treatment risks and benefits. See our editorial standards for more details.

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Anna Mizerska

Masters in Global Health and Biomedical Engineer
Anna is a highly analytical and insightful professional with progressive experience in providing quality services in fast-paced and high-pressure environments. Over the years she has built up extensive knowledge, expertise and transferable skills that translate into writing reliable medical content and articles. presents all health information in line with our terms and conditions. It is essential to understand that the medical information available on our platform is not intended to substitute the relationship between a patient and their physician or doctor, as well as any medical guidance they offer. Always consult with a healthcare professional before making any decisions based on the information found on our website.
Klarity is a citizen-centric health data management platform that enables citizens to securely access, control and share their own health data. Klarity Health Library aims to provide clear and evidence-based health and wellness related informative articles. 
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