What Factors Affect the Color of Pus?

Pseudomonas aeruginosa bacteria, which can make blue pus.
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  • Written By: Kathleen Howard
  • Edited By: Kaci Lane Hindman
  • Last Modified Date: 21 March 2014
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Pus is a thick liquid produced as a response to infection. This liquid is primarily made up of neutrophils, or white blood cells, that fight and kill bacteria. In most cases, pus is white or yellowish in color but may also appear red, green, brown, or in very rare cases blue. The color of pus largely depends on the infection the body is fighting. Pus also varies in color depending on the other substances it contains.

While fighting an infection, the body will normally create white, yellow or clear pus. White and yellow pus is created as a response to common bacteria, including Streptococcus pyogenes and Staphylococcus aureus. This bacteria is responsible for dozens of different infections, ranging from minor skin conditions like pimples to deadly diseases like meningitis.

While the presence of light pus is common, it should not always be ignored. Since there are many serious causes of pus, the condition might need to be investigated by a medical professional. Depending on the amount of pus and severity of the condition, antibiotics might be prescribed to help fight the infection.


Pus can also take on a reddish color. Red pus is usually due to blood mixing with the pus cells. This frequently occurs in urinary tract infections as well as certain skin infections like pimples and boils. The presence of blood does not necessarily mean that the body is having trouble fighting the infection. A reddish color of pus usually only indicates that the skin has become very irritated.

Green is another common color of pus and might mean one of two things. This pus may be caused by Corynebacterium diphtheriae, which is an uncommon infection of the upper respiratory tract. Pus can also get a green coloring from an antibacterial protein called myeloperoxidase. This brightly-colored protein is naturally produced by certain types of white blood cells.

Brown pus is a sign of an amoebic liver abscess, which is caused by the parasite Entamoeba histolytica. If left untreated, these abscesses can burst and spread the infection to the lungs, brain and heart. Symptoms of an amoebic liver abscess include abdominal pain, fever, chills, diarrhea, jaundice, joint pain and weight loss.

Blue pus is the least common of all the different types of pus. This color of pus indicates an infection caused by Pseudomonas aeruginosa, which typically infects the urinary tract, pulmonary tract, lungs, kidneys and blood. Burn wounds are especially vulnerable to Pseudomonas aeruginosa. If left untreated, these infections can become fatal.


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Post 5

I had a pimple on my chest and it was the first one I ever had. I popped it and at first there was a green chunk of something then the pus came out. It was white but then a few more little green chunks came out. I don't know what that means.

Post 4

My husband got swimmer's ear last summer, and though the pus that drained out was mostly yellow, it did have a bit of a blue tint to it. It was kind of strange to see this coming out of his ear.

His most intense symptom was the pain. His ear ached no matter what he did, and the canal was quickly swelling shut. He had to go to a doctor for relief.

She gave him some strong antibiotic ear drops. I had to pull his ear lobe down and back to open up the canal before dropping in the medicine.

The pus went away before the pain did, but he eventually got better. I had never seen blue pus before, and it did alarm me. I'm glad he got treated for it quickly.

Post 3

I got an eye infection as a child, and green pus collected at the corner of my eye. That wouldn't have been so alarming by itself, but what really bothered me was when I would wake up with my eyelids stuck together.

Pus had been oozing out during the night, gluing my lashes shut. I was very scared when I could not open my eyes the next day.

My mother soaked my eyelids with a damp, warm cloth, and the glue loosened up. I had a lot of dried pus that had crusted on my lashes, and there was plenty of it in the corner, as well. My doctor gave me medicated eyedrops, and I got better quickly.

Post 2

@Oceana – I get pimples on my scalp that contain a lot of white pus, and just like facial acne, it turns to pinkish goo at the end. These scalp pimples are particularly painful to pop, because they tend to go deep.

I have to position my fingers about half an inch from the center of the bump before I squeeze. This way, I can reach down to the source of the pus and send it shooting forth like toothpaste from a tube.

I am always amazed at how much comes out. Sometimes, it shoots out so quickly that it hits the mirror. It looks like a little white blob, and a bit of liquid surrounds it, and it resembles salad dressing that has separated.

Even though the bumps are painful and tender to the touch, I know that the are not dangerous, since the pus is white. It's nice to have a color guide to follow regarding pus and its degree of danger.

Post 1

I have noticed that small pimples tend to contain white pus, while the ones that run deeper and get larger contain yellow pus that resemble the creamy color of mayonnaise. I do pop them, even though I've heard that this is unwise. I just can't leave something that disgusting to fester on my face.

I've also observed that though the first pus that comes out is cream-colored, the pus behind it is pink and mixed with clear fluid. When this starts to come out, I know that it is time to quit squeezing, because blood will follow.

Sometimes, even after I think I've gotten all the pus out, it will reform the next day. Then, I squeeze the rest of it out. Once it is all gone, a small scab usually forms as the spot heals.

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