What Does Yellow Phlegm Mean


Mucus is secreted in many parts of the body; it is there to help prevent germs and particles from getting in. So when you suddenly produce lots of it, your body is actively trying to clear something. The consistency and colour of your mucus can give you an indication of what your body is trying to fight. When talking about the mucus from your lungs and lower airways it is referred to as phlegm.1 Yellow phlegm is a great example of your body fighting something off, typically a mild infection. The cells in your body responsible for fighting off infections are the white blood cells. When these white blood cells get into the mucus, they can give it a yellowish colour.2,3 

What is phlegm? 

Phlegm is the mucus produced in the lungs and lower airways. The body makes mucus to trap

pathogens (germs) and other contaminants where there is an opening that is exposed to the outside world. Usually, the body does not produce noticeable amounts of phlegm unless the person is experiencing a cold or has a different underlying medical condition. When the phlegm builds up at the back of your nose or throat, it is referred to as catarrh.4 When you cough it up and spit it out, it is called sputum. The mucus coming from your nasal passage is what we all know as snot.1 

Colours of Phlegm 

Phlegm can have different colours. The most common colours are clear phlegm, white, cream, yellow, green, and red phlegm, but you can also experience brown or black phlegm.2,5

What does yellow or green phlegm mean?

When you find that your phlegm is yellow in colour, it typically means that your body is

fighting off a mild infection. However, when you find it is greener in colour, this usually is an indication that your body is trying to fight off a more serious infection using a more robust immune response. The green colour comes from the abovementioned white blood cells, mixed with the germs causing the infection and other cells and proteins that are being produced by the body’s immune response. 

Even though green phlegm indicates that there is an ongoing infection, you do not always need antibiotics.3,5,6 Most infections that make green-coloured phlegm are viral and typically resolve on their own in a few weeks. It may even change back to white in a few days! When this does not happen, it might be a bacterial infection.

Please note that if you have green phlegm and breathing difficulties, chest pains, or

coughing up blood, you need to seek urgent medical care.2,3,5,6


Bronchitis has symptoms similar to those of a cold or flu, although it is an inflammation

of the lining of your bronchial tubes. It is also known as a chest infection. For either acute bronchitis or chronic bronchitis, the phlegm or sputum produced can vary in colour; clear, white, yellowish-grey, or it can even be green. It is very rare that it is streaked with blood. Bronchitis is more severe than a common cold but not as bad as pneumonia.6,7  


Pneumonia is an infection of one or both lungs and can be caused by viruses or bacteria. It can

also be caused by aspiration; this happens when material from the mouth or the stomach enters the lungs. With pneumonia, you can cough up phlegm that is yellow, green, or even bloody!8


When you have sinusitis, you will have a runny nose producing loads of yellow snot due to a sinus infection. It can be caused by (seasonal) allergies, a virus, or bacteria. When the infection is bacterial, you may notice yellow or green phlegm.9

Cystic fibrosis

Cystic fibrosis (CF) is an inherited chronic lung disease where sticky phlegm builds up in the lungs and mucus in the digestive system. The phlegm colours in CF can range from yellow to green to brown.1,10

What does brown phlegm mean?

When your phlegm seems to be rust-coloured or brown, this means there is old blood present. Before this happens, you have usually seen red or pink phlegm. It is typically caused by a bacterial infection,3,6 but can also happen when you have inhaled coal or asbestos dust, causing a chronic lung disease called pneumoconiosis or anthracosis. This takes years to develop. You may also discover you have black-pigmented sputum called melanoptysis with this condition.11 When you find that your sputum is black in colour, you may have a fungal infection. Please see your doctor immediately.12

Bacterial infection 

When you have bacterial pneumonia, you can produce phlegm that is green-brown or

rust-coloured. Also, when you have bacterial bronchitis, you can have a rusty-brown discharge as it advances. Please be aware that if you have a lung abscess you will have foul-smelling phlegm, besides it being brown in colour or streaked with blood. This means you have a cavity filled with pus inside your lungs, so go see a doctor immediately!8,13

What does white phlegm mean?

You may experience white phlegm with a few health conditions, but it is important to note that if you have difficulty breathing, you must seek immediate medical attention.

Medical conditions which cause white phlegm:

Viral Bronchitis

When you get this type of viral infection, it may well start off with white phlegm, but you can also catch a secondary bacterial infection, which will make you produce yellow or green phlegm.14,15


GERD stands for gastroesophageal reflux disease and is a chronic condition that affects your digestive system and causes heartburn and acid indigestion. It may cause you to cough up some thick white phlegm.16


When you have chronic obstructive pulmonary disease (COPD), your airways start to narrow, and your lungs produce excessive mucus. This combination makes it hard for your body to receive oxygen from the lungs, causing breathing difficulties. It may cause you to cough up white phlegm too.2,17

Congestive heart failure

When you are in heart failure, your heart fails to pump blood effectively to the rest of your

body, causing fluid to build up in different areas (oedema). It is called congestive heart failure because the fluid will also collect in your lungs causing breathing difficulties. This fluid in the

lungs can lead to an increase in white phlegm. It may also turn pink and frothy when you are in a later stage of congestive heart failure. You may also experience extreme breathing difficulties, sweating, and chest pains. Please seek urgent medical attention immediately if you are experiencing these symptoms.18

What do changes in phlegm texture mean? 

Since phlegm is a normal part of everyday bodily functions, the consistency of your phlegm also matters. The scale ranges from frothy or mucoid, going from mucopurulent to purulent, which means thick and sticky. The phlegm may get thicker and darker as an infection advances. If you do not hydrate properly, you may also find that your phlegm is thicker in the morning. 

Clear phlegm is typically associated with allergies and is not as thick or sticky as the green phlegm you see with bacterial bronchitis or the black phlegm that comes from a fungal infection.12,19

How to clear phlegm 

Some of the above-mentioned conditions are viral, so they will not respond to antibiotics. The best advice here is to hydrate, rest, eat well, and be kind to yourself. Eat some chicken soup.

Additionally, you could try some home remedies, like using a humidifier or steamer. The moist air can help the phlegm loosen and make it easier to cough up. You can also try gargling salt water to loosen any mucus. The same goes for lemon juice diluted with water. Honey can also bring some relief, especially if you also have a sore throat.

You can get some over-the-counter Vicks VapoRub, which contains eucalyptus oil. This is an essential oil that is said to help loosen the phlegm in the chest. Furthermore, over-the-counter expectorants can be taken, containing guaifenesin (like Mucinex) to help thin the mucus.20


Mucus, phlegm, sputum, and snot, are all forms of discharge signalling that your body is trying to ward off something. When you notice you are producing more than usual or you find it to be a different colour than what you are used to, please pay attention, as there are times when you need to see your doctor straight away. For instance, when you find yourself spitting up black, brown, or red mucus, make an appointment with your healthcare provider. Additionally, when your sputum is frothy, it is best to seek medical attention immediately, as you may have a more serious underlying condition.


  1. Rubin BK. Mucus, phlegm, and sputum in cystic fibrosis. Respir Care. 2009 Jun;54(6):726–32; discussion 732.
  2. Miravitlles M, Marín A, Monsó E, Vilà S, de la Roza C, Hervás R, et al. Colour of sputum is a marker for bacterial colonisation in chronic obstructive pulmonary disease. Respir Res. 2010 May 14;11:58.
  3. Shoar S, Musher DM. The white blood cell response in sputum in viral and bacterial pneumonias. Open Forum Infect Dis. 2022 Jul;9(7):ofac189.
  4. Cathcart R. Catarrh [Internet]. [cited 2022 Aug 30]. Available from: https://www.entuk.org/patients/conditions/37/catarrh/
  5. Johnson AL, Hampson DF, Hampson NB. Sputum color: potential implications for clinical practice. Respir Care. 2008 Apr;53(4):450–4.
  6. Butler CC, Kelly MJ, Hood K, Schaberg T, Melbye H, Serra-Prat M, et al. Antibiotic prescribing for discoloured sputum in acute cough/lower respiratory tract infection. Eur Respir J. 2011 Jul;38(1):119–25.
  7. Bronchitis [Internet]. nhs.uk. 2017 [cited 2022 Aug 30]. Available from: https://www.nhs.uk/conditions/bronchitis/
  8. Pneumonia [Internet]. nhs.uk. 2017 [cited 2022 Aug 31]. Available from: https://www.nhs.uk/conditions/pneumonia/
  9. Sinusitis(Sinus infection) [Internet]. nhs.uk. 2018 [cited 2022 Aug 30]. Available from: https://www.nhs.uk/conditions/sinusitis-sinus-infection/
  10. Cystic fibrosis [Internet]. nhs.uk. 2017 [cited 2022 Aug 31]. Available from: https://www.nhs.uk/conditions/cystic-fibrosis/
  11. Martínez-Girón R, Mosquera-Martínez J, Martínez-Torre S. Black-pigmented sputum. J Cytol. 2013 Oct;30(4):274–5.
  12. Lu HW, Mao B, Wei P, Jiang S, Wang H, Li CW, et al. The clinical characteristics and prognosis of ABPA are closely related to the mucus plugs in central bronchiectasis. Clin Respir J. 2020 Feb;14(2):140–7.
  13. Kuhajda I, Zarogoulidis K, Tsirgogianni K, Tsavlis D, Kioumis I, Kosmidis C, et al. Lung abscess-etiology, diagnostic and treatment options. Ann Transl Med. 2015 Aug;3(13):183.
  14. Miravitlles M, Kruesmann F, Haverstock D, Perroncel R, Choudhri SH, Arvis P. Sputum colour and bacteria in chronic bronchitis exacerbations: a pooled analysis. Eur Respir J. 2012 Jun;39(6):1354–60.
  15. Albert RH. Diagnosis and treatment of acute bronchitis. Am Fam Physician. 2010 Dec 1;82(11):1345–50.
  16. Heartburn and acid reflux [Internet]. nhs.uk. 2017 [cited 2022 Aug 31]. Available from: https://www.nhs.uk/conditions/heartburn-and-acid-reflux/
  17. Omori H, Higashi N, Nawa T, Fukui T, Kaise T, Suzuki T. Chronic cough and phlegm in subjects undergoing comprehensive health examination in japan - survey of chronic obstructive pulmonary disease patients epidemiology in japan(Scope-j). Int J Chron Obstruct Pulmon Dis. 2020;15:765–73.
  18. Heart failure - Symptoms [Internet]. nhs.uk. 2017 [cited 2022 Aug 31]. Available from: https://www.nhs.uk/conditions/heart-failure/symptoms/
  19. Tambascio J, de Souza HCD, Martinez JAB, Afonso JL, Jardim JR, Gastaldi AC. The influence of purulence on ciliary and cough transport in bronchiectasis. Respir Care. 2013 Dec;58(12):2101–6.
  20. Chest infection [Internet]. nhs.uk. 2017 [cited 2022 Aug 31]. Available from: https://www.nhs.uk/conditions/chest-infection/
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.

Get our health newsletter

Get daily health and wellness advice from our medical team.
Your privacy is important to us. Any information you provide to this website may be placed by us on our servers. If you do not agree do not provide the information.

IIona Kosten

Master of Science - (MS), Immunology and Infectious diseases, Vrije Universiteit Amsterdam (VU Amsterdam), Netherlands

Ilona has a BSc and MSc in Biomedical Sciences and a PhD in Immunology with a sweet spot for “all things allergy”.
She’s published a number of articles in peer reviewed journals ranging from skin and mucosa tissue engineering, immunoassays, DCs, LCs and T cells."

Leave a Reply

Your email address will not be published. Required fields are marked *

my.klarity.health 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. 
Klarity / Managed Self Ltd
Alum House
5 Alum Chine Road
Westbourne Bournemouth BH4 8DT
VAT Number: 362 5758 74
Company Number: 10696687

Phone Number:

 +44 20 3239 9818