What Factors Affect the Smell of Pus?

The smell of pus is determined by the type of bacteria present.
An ingrown hair with yellow pus.
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  • Written By: Erin J. Hill
  • Edited By: Bronwyn Harris
  • Last Modified Date: 29 August 2014
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The smell of pus is primarily affected by the type of bacteria causing the infection. Most bacteria which cause odor are anaerobic bacteria, since they produce volatile sulfur compounds as they grow. The way pus smells is much less offensive when the bacteria causing the issue are aerobic in nature, meaning they require oxygen in order to thrive. In many cases, the more severe the infection, the more offensive the odor of the pus produced. This is generally because more pus is produced in more widespread infections.

Pus is a substance produced by the human body when there is an infection present. This can include simple issues like acne pimples and more severe infections like abscesses and stomach ulcer infections. When bacteria enter an open wound or delicate area of the skin, the body sends white blood cells to fight the infection. It also produces substances to help flush out the pathogens. These substances combined with oils, dead skin cells, and other matter combined with the bacteria and white blood cells combined to form pus.


Since pus is generally filled with bacteria, the smell of pus is largely determined by the type of bacteria present. This explains why some pus-filled wounds have virtually no odor at all, and why others have a very strong smell. The more sulfur-producing bacteria present, the more likely the smell of pus will be strong and offensive. This may also mean that pus which has a strong odor is more contagious because more bacteria are present.

It is normal for pus to have a smell to some extent, but any serious infections should be checked by a doctor. The factor which determines a serious infection is not so much whether pus has a smell, but the extent of other symptoms. Open wounds that are widespread or very large, or those accompanied by a fever should be investigated by a doctor. In some cases antibiotics will be needed in order to kill the offending bacteria.

The smell of pus doesn't generally have anything to do with one's hygiene or cleanliness. Even very clean individuals can acquire an infection with malodorous pus. Many forms of infection affect the skin when bacteria enter pores, hair follicles, or oil glands. These are relatively common and affect most people from time to time. More serious infections can occur after an injury or illness, and these are more likely to require medical treatment.


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Post 3

This is a weird but interesting subject. The smell of pus certainly gives us an idea about what's going on with a wound. How else would we know if a wound requires further treatment?

Post 2

@burcidi-- I'm not in the medical field, so it might be best to ask your doctor. But as far as I know, a yellowish or greenish colored, and very bad smelling pus points to a serious infection.

Most simple infections like acne and skin cysts will have lighter colored discharge like you said. There won't be much of a smell either. But more serious infections make pus smell really bad.

I had a bad ear infection last year with discharge and it smelled awful. Consequently, I had to take three different courses of antibiotics to get rid of the infection.

Post 1

So I guess the pus that forms on pimples are caused by aerobic bacteria and the infection isn't very serious, right?

Whenever I clean pus on pimples, I notice that the pus is clear and almost odorless. There is a slight odor, bu it's not foul, it smells like oil to me.

Is there also a connection between the color of pus and the smell of it?

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