Written by Cheyenne Buckingham, BS | Reviewed by Patricia Pinto-Garcia, MD, MPH
Published on January 9, 2023
Key takeaways:
Green mucus has long been said to be a sign of an infection, but that’s not actually true in some cases.
Mucus plays an important role in the body. It works with your immune system to protect you from illness.
In fact, other symptoms such as fever and trouble breathing are bigger signs of infection than green mucus alone.
Drazen Zigic/iStock + via Getty Images Plus
Not feeling well can put you in a uniquely vulnerable position — your mind can, at any moment, spiral into a state of worry. Spotting green mucus in your tissue is one such symptom that may trigger anxiety.
As a child, you may have learned green mucus was a telltale sign of an infection. And yes, while green mucus is certainly a symptom, by itself, it is often not enough evidence to hop on a round of antibiotics. At least, not right away.
Below, two healthcare providers unpack what green mucus means, why it happens in the first place, and when to get treatment.
What is mucus?
Mucus is a thick, slippery liquid that lines your:
Mouth
Nose
Sinuses
Lungs
Cervix
Gastrointestinal tract
Lower genitourinary tract (which includes the bladder, urethra, and vagina)
“It is always present under normal circumstances and is helpful in the protection against air pollutants or bacteria because it not only provides a coating, but it contains helpful antibodies and enzymes,” said Jayne Morgan, MD, creator of the Stairwell Chronicles and executive director of health and community education at Piedmont Healthcare.
In the case of the sinuses, for example, mucus works to shield the body from illness. It not only helps keep the nasal passage moist, but it also catches viruses or bacteria before they can infect you. Think of a fly getting caught in a sticky trap — the fly is the infection-causing germ and the sticky trap is the mucus that lines your nose and lungs.
“[Mucus] has many functions, such as lubricating those surfaces to prevent injury, capturing germs that can then be eliminated, and preventing water loss,” said Zach Willis, MD, MPH, an assistant professor of pediatrics and pediatric infectious diseases physician at UNC School of Medicine.
In short, mucus is what helps to block bacteria and viruses. “Think of mucus as a line of defense,” said Morgan.
Why is green or colored mucus considered bad?
Health experts have long reported that green mucus is a sign of a more serious infection. Though, green mucus is a natural part of the body’s immune response when it’s fighting off illness.
“It is true that prolonged nasal drainage symptoms can be a sign of bacterial infection, but generally, we start to think of that when it’s been 7 days or more, or when someone starts to get better then gets worse again,” Willis said.
Claim: Green mucus means you have an infection
Yes and no.
“The color of the mucus does not have much meaning,” Willis said. “However, because yellow and green mucus tend to happen later in the infection, that is when people start to worry that their infection has been going on for too long, which is taken as a sign that maybe they need an antibiotic.”
What does the science say?
As Willis pointed out, the color of your mucus doesn’t mean a lot on its own.
For example, in one study, scientists found only around 12% of green mucus samples collected from participants with a cough and no other lung conditions were caused by a bacterial infection. This means it is possible to have green mucus without having a bacterial infection.
As a result, the study authors noted that mucus color alone does not always mean you need antibiotics if you don’t have any other lung conditions.
What do the experts say?
“If your mucus becomes green and you are also experiencing fever, shortness of breath, [and/or] chest pain, then those are signs that you may have something more serious going on, and you should see a doctor,” Morgan said.
In general, yellow or green mucus is a sign that the body is working hard to fend off infection, she explained. “These are white blood cells rushing to battle, then they are flushed out.”
In fact, it’s completely normal for your body to make more of this type of mucus when you’re sick. Mucus, in part, serves as an added barrier that blocks any other germs from entering the cells in your respiratory tract, Willis explained.
“When that happens in the nose and sinuses, you get a runny nose and sometimes sinus fullness and pain,” he said. “That happens whether the infection is bacterial or viral, and most infections of that part of the body are viral.”
In other words, most sinus infections are caused by viruses — not bacteria.
Willis added that his patients will often say they have these symptoms and want to know if there is an antibiotic they can take to help speed up their recovery. But, since antibiotics are only designed to treat bacterial infections, they’re not recommended for viruses or any other type of infection.
In fact, not only will they not be effective against non-bacterial infections, but taking too many can lead to antibiotic resistance. This is when antibiotics no longer work against bacteria, making it more challenging to treat the infection.
So, should I be concerned if my mucus is green?
“There is generally no cause for concern,” Morgan said, adding that this color of mucus likely suggests the body is already successfully fighting off an infection.
“If it is of concern, medications such as decongestants, anti-histamines, [and] expectorants, could be useful,” she said.
But, if you feel like it’s time to see a medical professional, Willis said it’s best to see your primary care physician (PCP).
“They know your medical history, medications, and allergies,” he said. “Also, they will be better able to follow up.”
If you don’t have a PCP, you can still talk with a healthcare provider at a local medical center, urgent care, or through a virtual visit.
If you have an underlying lung condition, any change in your cough or mucus could be a sign that you’re having a flare. If you notice green (or any color) mucus, talk to your healthcare provider as soon as possible.
The bottom line
Remember, green mucus isn’t always an indicator of a serious infection. In fact, green mucus is a normal immune response. But, if it’s been a few days and your symptoms have shown no signs of improvement, then it’s time to contact a healthcare provider.
References
Altiner, A., et al. (2009). Sputum colour for diagnosis of a bacterial infection in patients with acute cough. Scandinavian Journal of Primary Health Care.
Asthma and Allergy Foundation of America. (2021). Sinusitis (sinus infection or sinus inflammation).
Leave a Reply