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Coughing Up Green or Yellow Phlegm

Mucus is your body’s way of dealing with an infection, and it’s not always bad.
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Last updated March 4, 2021

Phlegm questionnaire

Use our free symptom checker to find out what's causing your phlegm.

Phlegm questionnaire

Use our free symptom checker to find out what's causing your phlegm.

Phlegm symptom checker

What is phlegm?

When you get a cough, you may start to see thicker, darker mucus come up. Mucus is a normal fluid produced by many parts of the body.

It keeps certain tissue in your body from drying out. It’s also your body’s front line of defense because it traps germs and other foreign particles.

Phlegm is a type of mucus that your lungs produce and comes up when you cough. When you cough up a lot of phlegm and it’s yellow or green, it usually means you have an infection or other lung condition.

How mucus does its job

The airways of the lung constantly make mucus. The cells that line the airways have small hairs called cilia.

The cilia rhythmically beat back and forth, sweeping mucus up out of the airways and into the mouth. The mucus takes with it any foreign particles, like dirt, dust, or bacteria. This keeps the airways clean and free from infection.

Phlegm questionnaire

Use our free symptom checker to find out what's causing your phlegm.

Phlegm symptom checker

What can you tell by the color and consistency of phlegm?

When the lungs become infected, either from bronchitis (inflammation of bronchial tubes) or pneumonia (inflammation of air sacs), they often create more mucus.

Infection may cause mucus to change from a clear or light yellow thinner liquid to a darker thicker one. Mucus can become darker yellow or green. The dead white blood cells and other changes from the body’s response to infection cause this color change. The change in color may mean that your body is fighting off an infection. But not always.

There is some evidence that green or yellow phlegm is more often caused by a bacterial infection (as opposed to a virus). It’s just not a guarantee, so your doctor will look at other symptoms to decide which type of infection you have—a bacterial one or a viral one.

Other symptoms you may have

If you have mild symptoms such as a cough, congestion, and sore throat for a few days, it’s likely you have a common cold from a virus. Colds can make you cough up phlegm as the body fights the infection. But once the infection is gone, the phlegm should also go away.

Longer lasting symptoms, or more severe symptoms such as fever or shortness of breath may indicate a bacterial infection (such as pneumonia) that requires an antibiotic. You will only be given antibiotics for bacterial infections, since antibiotics don’t help fight off viruses.

Sometimes, you can have brown or red phlegm. This is usually caused by some bleeding, which can happen from an infection, but can also be from other conditions.

A small amount of red-tinged phlegm that goes away within a few days and occurs while you’re sick with an infection is generally nothing to worry about. However, you should let your doctor know this happened next time you see them.

Call your doctor if you’re coughing up any significant blood or go to the emergency room if your doctor is not available.

Are antibiotics needed to treat green or yellow phlegm?

"It is a common misconception that a cough with new green or yellow phlegm means you have a bacterial infection needing antibiotics. The phlegm may be from a variety of infections (viruses or bacteria) and rarely are antibiotics required in those without an underlying lung condition. For common chest colds, antibiotics do not decrease the duration of symptoms and can have dangerous side effects." —Dr. Benjamin Ranard


Other causes of phlegm

Exposure to toxins or chemicals (like cigarette smoke) can make you produce more mucus. The lining of the airways become irritated and produce mucus to help clear away the pollutants. Over time smoking can lead to increased mucus production even after quitting smoking.

People with a lung condition, such as chronic obstructive pulmonary disease (COPD), may also have darker yellow or green phlegm. This disease is more common with age. And it is especially common in people who smoke cigarettes.

However, there are other chronic diseases that can lead to more mucus production and more coughing up of phlegm such as cystic fibrosis or bronchiectasis.

Not all mucus comes from the lungs. The nasal passages can create mucus. This can happen from a common cold. It can also be from allergies such as hay fever.

When the mucus drips down the back of the throat (postnasal drip), it can cause coughing that is sometimes mistaken as phlegm coming from the lungs.

Is it normal to have constant phlegm?

"If you’ve been living with chronic cough and mucus, talk to your doctor about what may be causing the mucus. There may be easy treatments for the underlying cause—and it is important to try and figure out if there is an underlying condition causing the mucus." —Dr. Ranard


Phlegm questionnaire

Use our free symptom checker to find out what's causing your phlegm.

Phlegm symptom checker

How to get rid of phlegm

Phlegm that occurs with mild symptoms can be treated at home. You can try taking an over-the-counter cough suppressant (such as dextromethorphan) and/or an exportant to help thin the mucous (such as guaifenesin). Be sure to follow the directions on the package.

If you have more severe or long-lasting symptoms, you should see a doctor. They can help figure out what is causing the phlegm and the best way to treat it.

What questions will your doctor ask?

"I want to know how long has this been going on? Is it getting better or worse? And whether anything seems to improve or worsen the condition." —Dr. Ranard

Hear what 1 other is saying
Not ladylike to spit!Posted June 16, 2021 by J.
I was a cigarette smoker of over 10 years; I also smoked marijuana for over 10 years. When I had that chest feeling of a cold or similar to bronchitis coming along I didn't think much of it at first. I had coughed up some really thin, almost watery mucus a few times & all I could hear was my stepmom in the back of my mind saying it was not ladylike to spit, especially a big ole mucus-filled spit. So I would never spit it out ever since I was little. So a few weeks of mild chest congestion passes when I got hit with bronchitis from what the doctor said. When this happens your airways become swollen or restricted, which traps that mucus down in your lungs, especially if you're like me & didn't spit it out as it came up. So the doctors told me this was similar to a wet sponge being left in the sink. It's a breeding ground for bacteria. That's exactly what happened. I had thought I had finally gotten over the bronchitis after an ER trip where they gave me a breathing treatment & prednisone (a steroid to open my airways) then sent me home. I thought I was all cleared up when I got hit even worse than the first time. I was trying so hard to spit out anything I could get to make it up through the narrow airways. After about a week or so of this second round, I was at 86% oxygen. I thought I might actually die—I couldn't walk up the stairs without losing my breath completely. So freaked out I went to the ER again. This time they admitted me for 5 days where I quit smoking completely. They gave me antibiotics, steroids, and breathing treatments every 4 hours. I hacked up first a very thin mucus again, almost watery. Then I started to hack up the dark green, thick, almost booger consistency mucus, and as I did the more clear my lungs felt & the better I was able to breathe. So the doctor diagnosed me with asthma & possibly pre-COPD. I am 30 years old & not in terrible shape & never had a breathing problem prior to this. I was so thrown back to hear him tell me this, especially because both my grandparents have COPD. From what the doctor explained to me, it is because I waited weeks to come into the ER. The first time when I noticed the mucus & had a bad cough I was not properly diagnosed because they had no non-intrusive way to ACTUALLY tell if you had COVID, pneumonia, or bronchitis. The only way to know would be to go in & biopsy some of the mucus for testing. So because the bacterial infection wasn't treated, it grew & in turn made even more mucus in my already full & tight airways & lungs. It had sat in my lungs so long and I had run out of my preventative inhaler a few months later for a week or two. The result has so far been even worse on my lungs. I finally got antibiotics again and breathing treatments, but I am still going back and forth between thick green mucus to a clear or light yellow super-watery mucus. My lungs have been forever damaged from not clearing them out when it happened. Half the time I didn't even realize that I was missing as much lung capacity as I actually had been. I am still trying to figure out what's a good sign to go off of that my lungs are completely clear of all things they should be since I now have asthma and it seems like my lungs are constantly creating an excessive amount of mucus. I feel that makes it harder to get the thicker stuff from the bottom of my lungs out too. The dark green mucus, as gross as it sounds, gave me a nasty taste in the back of my throat when I would have a deep cough. It sounds so gross, however, I could taste the infection or bacteria, but other than that I almost would have just assumed that my lungs are adjusting & allergies are acting up combined with the asthma. This can be extremely dangerous, so it's better to just go to the doctor to be safe.

Dr. Ranard is a Pulmonary and Critical Care fellow at Columbia University Irving Medical Center / NewYork-Presbyterian Hospital. He received his undergraduate degree in Biological Sciences from Cornell University (2011) and his Doctor of Medicine and Masters of Science in Health Policy Research from the University of Pennsylvania Perelman School of Medicine (2016). In addition to pulmonology and critical care medicine, Dr. Ranard is interested in health care redesign, health policy, and looking for ways to improve the quality of care for all patients.

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