Is Green Mucus Viral Or Bacterial

The myth about the connection between the colour of mucus and the type of an infection was debunked long ago. It has been settled that you cannot depend on the colour or consistency of nasal discharge to determine viral or bacterial sinus infections, or even whether you’re dealing with an infection at all. Both bacterial and viral upper respiratory infections can create similar changes to the colouration and type of nasal mucus. 

It’s part of our immune system, and it comprises every inch of our body exposed to air that’s not secured by skin, including inside our nose. The sticky substance defends the body by trapping viruses, bacteria, dirt and dust, and keeping them from penetrating our body through the nose.

While having common flu, the phlegm may start out watery and clear, then grow progressively thicker and more cloudy, taking on a yellow-on-green colouration. This tinge is likely due to a rise in the number of specific immune system cells, or an increment in the enzymes these cells produce.1,2

Having green snot or phlegm 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).3

Understanding mucus

Colors of mucus and what does it mean? 

The colour of the snot can tell you a lot about what’s going on inside your nasal passages. Phlegm colour can tell you many things, including whether you have a nosebleed, allergies, a sinus infection or a cold. However, changing mucus colour is almost a bigger sign that something is up with your health. If you’re still sick after about 10 to 12 days, you may want to see a doctor. It could be sinusitis, a bacterial infection that is treated with a course of antibiotics. Phlegm comes in various colours from white to mustard-yellow to varying shades of green. Coloured mucus does not mean you need antibiotics. In most vigorous people, phlegm production without or with a cough will stop as your flu or cold clears up, although it may take up to 3- 4 weeks.4 

Why mucus changes color

This colouration is likely due to the increasing in the number of certain immune system cells, or an increment in the enzymes these cells produce.2

What causes green mucus?

When the white blood cells in the sheath come across an infectious organism or irritant, they respond by producing enzymes to withstand the invaders. These enzymes consist of iron, and that’s what gives the phlegm the green colour. And if the mucus sits around, it turns more concentrated and so may appear darker green or yellow. This is the natural order of things, whether the responsible agent is a virus (which is the most common cause of sinusitis) or a bacterium. White blood cells charge to battle infection, and when they’ve done their job, they get cleared out of the body along with the virus. The yellow colour originates from dead white blood cells, which can shift green if there are a lot of white blood cells and other debris.1

Is green mucus viral or bacterial

It has been settled that you cannot depend on the colour or consistency of nasal discharge to determine viral or bacterial sinus infections, or even whether you’re dealing with an infection at all. Good examples are seasonal allergies. They can generate all sorts of nasal discharge thick or thin, green, yellow or clear even though there’s no infection at all. Both bacterial and viral upper respiratory infections can create similar changes to the coloration and type of nasal mucus.1

How does it feel having a green mucus?

The timing of symptoms may show an indicator to the type of germs present. Thick, coloured phlegm more often appears at the beginning of a bacterial infection, rather than several days into it, as occurs with a viral illness. Additionally, symptoms due to a bacterial infection often last more than 10 days without improvement.

In some cases, a bacterial infection may build up on top of a viral cold, in which case symptoms may get better and then worse again.2

Ways to get rid green mucus 

Home remedies

The most important way is to drink plenty of fluids to stay hydrated. Moreover, it helps to gently suction out the mucus, using saline nasal drops to rinse out the nose, additionally using a cool-mist humidifier to moisten the air.2


To ease the symptoms you can use over-the-counter medication ie. to reduce nose swelling. In some cases, a bacterial infection may develop on top of a viral cold, in which case symptoms can improve and then get worse again. In this care, an antibiotic may ease the severity of symptoms and shorten the span of the illness. 

Natural remedies

It is helpful to gargle with salted water. To do that use 1 teaspoon of salt per glass of warm water, and it should ease your irritated throat by clearing away mucus. You can also use eucalyptus balm or essential oil in a diffuser, the essence of eucalyptus can help loosen phlegm.5


Key to any illness is to drink more water. In addition, use a humidifier, it can help your body moisturize your throat and nasal passages and may help reduce phlegm production. Moreover, check filters on cooling and heating systems. It is important to make sure the filters are clean and working well to keep dust and other potential irritants out of the air.5


Infection can persist for over 10 days, or even get worse after a week.

The discharge becomes thick and uniformly white and the high fever isn’t improving.

There are more severe symptoms that do not respond to the usual over-the-counter cold and sinusitis remedies.1

When to seek medical attention

Alarming signs are phlegm accompanied by chills, fever and night sweats, especially if you also undergo weight loss, nasal blockage or recurring nose bleeds for more than 2 weeks. It is vital to pay attention to the symptoms that come along with a switch in your mucus colour. Turmoil, loss of sense of smell, pressure or pain in face, and nasal congestion can help establish whether therapy with antibiotics or other medication is advised. Therefore, if you don’t have sinus pain or fever along with yellow mucus, the doctor will likely diagnose the common cold. But if you have intense pressure or pain in your face along with green mucus, the doctor can diagnose sinusitis and prescribe antibiotics.5,6

Brown or bloody mucus followed by signs like facial swelling and pain, altered mental status,  altered vision or high fever are serious symptoms and a visit to the doctor's office is needed promptly. If you have a bloody nose that lasts over 45 minutes, that also requires intervention.6


Because of its vital role, mucus can differ in colour if you’re experiencing an illness or other condition. It’s always valuable to be aware of what’s going on in your body, including what comes out of it. If you detect a change in your mucus that disturbs you, talk to your healthcare provider.  Healthcare professionals have the necessary medical training and access to diagnostic tests, which go much further than mucus tests.

Moreover, if a mucus colour change appears alongside other symptoms, such as dehydration, difficulty breathing, pain or symptoms that last for over 10 days, make an appointment to get it checked out.7

The colour of your mucus can be a good indicator of sickness or other conditions, and it’s one of your body’s many ways of reaching out to you. Understanding is a key even when it comes to something as appealing as your mucus.


  1. MD Shmerling RH. Don’t judge your mucus by its color. Harvard Health; 2016.
  2. Torborg L. Mayo Clinic Q and A: Nasal mucus color — what does it mean? Mayo Clinic News Network. 2018.
  3. Public Health England. Green phlegm and snot ‘not always a sign of an infection needing antibiotics’. GOV.UK. 2013
  4. Cleveland Clinic. Mucus color: what does it mean? Cleveland Clinic. 2021.
  5. Cleveland Clinic. Phlegm and mucus: how to get rid of it. Cleveland Clinic. 2022.
  6. Miller K. Experts explain what your mucus color means, and when to be concerned. Prevention. 2021.
  7. Penn Medicine. A Look at What Your Mucus Says About Your Health. Penn Medicine; 2020.
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.

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.

Leave a Reply

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