Abscess - Causes 

  • Overview

Causes of an abscess 

Most abscesses are caused by a bacterial infection.


When bacteria enter your body, your immune system tries to fight the infection by sending white blood cells to the affected area. As the white blood cells attack the bacteria, it causes inflammation (swelling) and the death of nearby tissue, leading to the formation  of a cavity.

The cavity fills with pus to form the abscess. The pus contains a mixture of dead tissue, white blood cells and bacteria. The abscess may get larger and more painful as the infection continues and more pus is produced.

Staphylococcus aureus and streptococci are the most common types of bacteria that cause skin abscesses on the following areas of the body:

  • head and neck
  • limbs
  • underarms
  • torso

Read more information about Staphylococcal infections.

PVL Staphylococcus aureus

Staphylococcus aureus (S. aureus) is a type of bacterium found on the surface of healthy skin, particularly in the nose and moist, damp areas such as armpits and groins. It can cause skin infections, such as skin abscesses and boils, and prefers to live in moist areas of the body such as the armpits and groin. 

Some S. aureus bacteria can produce a poisonous substance called Panton-Valentine leukocidin (PVL), which kills the white cells, causing the body to make more white cells to continue to fight the infection.

PVL-positive strains of bacteria are therefore more likely to cause skin infections and abscesses.

Both types of S. aureus can also cause more serious conditions such as:

  • septicaemia  blood poisoning caused by bacteria multiplying in the blood
  • pneumonia  swelling (inflammation) of the lungs caused by an infection

Skin abscesses

Bacteria can cause a skin abscess when they get under the surface of your skin. An abscess may occur if you have a minor skin wound, such as a small cut or graze, or if a sebaceous gland (oil gland) or a sweat gland in your skin becomes blocked.

Boils develop as the result of bacteria entering the root of a hair on your skin.

In most cases, skin abscesses are not a sign of an underlying health problem. However, you are more likely to develop a skin abscess if you have diabetes. Diabetes can cause nerve damage, which can mean you are unable to feel minor cuts and grazes to your skin.

Meticillin-resistant Staphylococcus aureus (MRSA) has been a common cause of skin abscesses in recent years. Read more about MRSA infection.

Internal abscesses

Abscesses that occur in the abdomen (tummy) can be caused by:

  • an infection
  • a tear (rupture) of the intestine
  • an injury
  • surgery to the abdomen

An abscess can develop inside your body when bacteria spread from an existing infection.

For example, a lung abscess can occur as a result of a bacterial infection in your lungs, such as pneumonia (inflammation of the lung tissue), that becomes isolated by the body's immune system. This then develops into a collection of pus (abscess). Bacteria can also spread from other areas of your body through your bloodstream.

Internal abscesses tend to develop in people who have an underlying health problem, such as a brain abscess that occurs after a head wound. Internal abscesses are also more common in people with weakened immune systems, such as those with HIV and AIDS or cancer.

Risk factors

Things that increase the likelihood of an abscess developing include:

  • trauma to a specific area of the body
  • a weakened immune system
  • any material getting into the body
  • a drainage system in the body becoming blocked
  • a build-up of fluid in the tissues of the body
  • a haematoma (collection of blood outside a blood vessel)
  • a PVL-positive strain of bacteria (see above)

Hidradenitis Suppurativa

Hidradenitis suppurativa is a rare inflammatory skin disease that can cause painful abscesses to appear in the armpits and groin.

It is a chronic (long-term) disease that often begins between ages 20-40. It is also more common in females.

The condition is believed to be caused by pores of the apocrine glands (found in the armpits and groin) becoming blocked, but the exact cause is not fully known.

Severe cases of hidradenitis suppurativa can lead to psychological affects or inflammation of the joints (arthritis).

Read more information about hidradenitis suppurativa.

Page last reviewed: 17/07/2012

Next review due: 17/07/2014


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The 3 comments posted are personal views. Any information they give has not been checked and may not be accurate.

Becs1234 said on 08 April 2013

I was diagnosed with Hidradenitis Suppurativa in September 2011. I had some success treating this with antibiotics. When they didn’t work I was plagued with boils and at times had 20 boils in my armpits. I also ended up with 3 boils on my face which caused my face to swell up. It was incredibly painful and made me desperate and miserable.
There didn’t appear to be any specific guidelines for how doctors should approach this treatment as the guidance stated that the treatment plan should be tailored to the individual. I am assuming that this is because some antibiotics work for some people but not for others.
Personally I found it really helpful to do my own research and I sought a second opinion as my dermatologist would not prescribe me the latest combination drug therapy.
I spoke to a number of doctors regarding their treatment plans and in the end selected a fantastic doctor in Cardiff (a bit of a trek from Leeds). I had photographed all of my symptoms and showed this to the doctor as well as an infection I had at the time.
I am a very active person and he said that this did not fit with Hidradenitis Suppurativa and that facial boils were not normally associated with this disease. He diagnosed me as having PVL Staphylococcus Aureus which is a community acquired MRSA. The GP took swabs from my groin, armpits and nostrils which tested positive for Staphylococcus Aureus but negative for PVL. However, the culture grown from the pus from a boil was positive for PVL!
So after a year of treatment for the original Hidradenitis Suppurativa I am in the clear. The MRSA has been eliminated from my system after a decolonisation regime (cleaning and drugs).
My advice is if you have been diagnosed with Hidradenitis Suppurativa rule out MRSA. Get swabs (intra nasal, axilla, groin and definitely from a pus sample produced by a boil) to rule out sensitivities and ask for PVL typing.
Good luck!

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LizH222 said on 15 March 2011

Yes indeed! I agree this should be on the NHS site. Do you get abscesses in your armpits/groin especially - never go away, if they do they soon come back ! Ask your gp to check this condition out. You can also log into the hidradenitis suppuprativa uk organization, just google the word. I suffered for 30 years with this (though my current gp does know about this cdt) - all the doctors & at the hospitals here in north west coast - treated them as boils - they cut them all the time - so painful when they did that, i would pass out, be sick etc and the nurses could never believe the amount that would come out once cut, it left me with permanent and awful scarring in groins and armpits. Do not let anyone cut them like a boil. Most doctors think they are and treat them so. Eventually I when i went to Aberdeen 10 years ago a doctor identified it - sent me to Aberdeen hospital and the operated & cut my armpit out (under anaesthetic ). They could not believe that the hospitals down here actually cut them & said it must have been like ‘torture’! It was. Lots of people seem to have this - yet a lot of gp's & hospitals don't know what it is !
Don't suffer in silence - check out the website.

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marshell said on 24 September 2009

No mention has been made here on a condition known as HIDRADENITIS SUPPURATIVA which I believe to be more common than is thought. This condition results in many abscess and is largely unknown to most Doctors. For anyone suffering from this condition, or anyone who has repeatedly suffered in this way go to www.ba-hs.org.uk/ for more information.

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