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Phlegm color is a health indicator

Consistently rated one of the worst words in the English language, "phlegm" is hardly a great conversation starter. Medically speaking, however, your phlegm can be an important barometer for your health. Serious changes in your phlegm can be a valid reason to speak to your physician.

"Color changes in your phlegm can mean a number different things health-wise. Importantly, you can observe these changes quickly and easily, and these can help you decide if you need to seek medical attention," explained Dr. Barbara Kreel, Geisinger otolaryngologist.

What is phlegm?

The body uses mucus to trap germs and contaminants. Many parts of the body produce mucus, like the GI tract, throat, nose, sinuses, mouth and more.

Phlegm is mucus from your lungs and lower airways that protects against germs and foreign contaminants like pollution.

"Clear phlegm is normal. It’s made of water, salt and other cells," said Dr. Kreel. "When you become sick, the phlegm may thicken as well as change color as your body fights off the infection."

Here are what some of the colors of your phlegm might be trying to tell you:


White phlegm is normally no cause for alarm. It indicates sinus activity and nasal congestion. As the airway passages get inflamed the phlegm in the respiratory tract can thicken and become white.


Yellow phlegm is a sign that your body is fighting off a mild infection.

"White blood cells are responsible for fighting infections, and as they get picked up in the mucus, they can cause it to have a yellowish hue," said Dr. Kreel.


Green phlegm is an indication that your body is fighting off a more serious infection. While the green color may be alarming, it is a natural byproduct of the immune system activity necessary to fight off the infection. Consider seeing your doctor if your other symptoms are getting worse.


Red or pink phlegm can be a more serious warning sign. Red or pink indicates that there is bleeding in the respiratory tract or lungs.

Heavy coughing can cause bleeding by breaking the blood vessels in the lungs, leading to red phlegm. However, more serious conditions can also cause red or pink phlegm.

"If you’re experiencing red or pink phlegm, you should talk to a physician sooner," said Dr. Kreel. "As a one-time symptom, it may not really be an issue, but if persistent, it might signal conditions

like tuberculosis or a pulmonary embolism. Determine if you are experiencing other symptoms which may indicate something serious, and always err on the side of safety."


Brown phlegm can also be a warning sign because it signals prior bleeding. As the blood ages, it turns brown. If you notice brown phlegm, you should see your doctor.


Black phlegm is cause for alarm—it likely signals a fungal infection, especially for people with compromised immune systems. You should see your doctor immediately.

"Bear in mind that phlegm discoloration is only part of the story," explained Dr. Kreel. "Just because your phlegm is white or yellow does not give you a clean bill of health. Phlegm color is a reference point that needs to be considered along with other symptoms. If you have any reason to think your condition is worsening or your symptoms are bad, talk to your doctor."

Geisinger otolaryngologist Dr. Barbara Kreel, MD, sees patients at Geisinger Wyoming Valley Medical Center in Wilkes-Barre. To schedule an appointment with Dr. Kreel or another ENT specialist, please call 800-275-6401 or visit

Man coughing