What Are the Common Causes of Dark Pus?

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  • Written By: Gregory Hanson
  • Edited By: Susan Barwick
  • Last Modified Date: 16 March 2019
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Dark pus can be caused by several specific types of relatively uncommon medical conditions. These conditions may produce pus with a dark brown, green, or purple color. In other cases, pus and blood may be found in the same area, and the mixture of these two substances can have a dark red appearance as a result of the presence of red blood cells in the mixture.

Pus occurs when the body is actively fighting off an infection. White blood cells target invading cells, and cells of both varieties die in large numbers. These cells and other associated biological byproducts of the body’s struggle with invading pathogens make up pus. Individual pus cells are typically whitish or yellow in color.

One of the very common causes of dark-colored pus is the mixture of ordinary blood cells with pus. This can occur when pus forms in an abscess or boil beneath the surface of the skin. Small blood vessels may be broken from pressure caused by an expanding boil or may rupture as a result of attempts to drain or puncture the boil.


In cases where dark pus is the result of this sort of mixture of blood and pus, there are few additional medical risks. Any boil or abscess that has burst should be treated as an open wound. This treatment will normally involve precautionary measures to prevent additional pathogens from infecting the body at the site of the wound. Medical advice should certainly be sought for larger boils or for those located on the face or in clusters, and it is best to err on the side of caution when deciding whether or not to seek a medical evaluation.

Other conditions may produce dark pus that is green or bluish in color. Certain bacteria produce chemicals that cause pus to take on a greenish hue. In other cases, the body’s response to particular types of infection may involve specific proteins that can also turn pus a shade of green. As a general rule, any large boil or other accumulation of dark-colored pus should be evaluated by a medical professional, as some infections can be quite serious and require medical treatment rather than home care.

Some patients may mis-identify other substances as pus. Tissue that has begun to break down as a result of a disease may have a foul smell and black appearance and be called “black pus”. This is not a true form of dark pus, but is indicative of a very serious medical problem that demands immediate attention. Other bodily discharges may have the same consistency as pus but very different underlying causes.


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Post 4

Two and a half weeks ago, I was watching my younger cousin skateboard when he fell off a ramp and the skateboard hit my leg extremely hard (knocked me to the ground). It has hurt like crazy since then. I was just massaging my leg and the scab popped off and a ton of black, goopy, black pus like stuff came out. I don't have insurance and do not want to go to the doctor if I don't have to. Any advice?

Post 3

I had brown pus in my throat when I had tonsillitis. It was quite bad. I had to take antibiotics for a long time. I know that the color of pus is important because it tells us how serious a infection is. But I hope I never experience this again because it's disturbing. The worst part about having pus filled pockets in the throat is getting them drained and tasting it in the process. It's just awful.

Post 2

@ysmina-- That's probably not pus, but normal cervical discharge mixed with old blood. It's normal for there to be brown spotting after periods. That's just old blood from your period finding its way out.

Dark pus from the cervix will be thick, dark yellow, green or brown. It will have a foul smell and it may be accompanied by pain during urination. This pus will occur regularly for a long time, it won't occur for a few days and then stop. If you experience something like that, then make an appointment with your doctor right away. It may be a urinary tract infection or a sexually transmitted disease.

Post 1

This month, a few days after my period was over, I found brown colored pus on my underwear. It continued for a few days. Does this mean that I have an infection?

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