What is an Abscess?

Warm compresses to promote drainage is the treatment for small abscesses.

An illustration of a boil forming under the skin.
An illustration of a boil forming under the skin. Dorling Kindersley/Getty Images

A skin abscess is a walled-off, bump-like collection of pus (thick, yellow-colored liquid) that appears either within or below the surface of the skin.

Abscesses are typically caused by a bacterial infection. They most often appear on the back, certain areas of the face, chest, or buttocks. Sometimes they occur in areas where hair is present, such as the armpits and pubic area.

A furuncle—sometimes called a boil—is caused by an infected hair follicle, which creates a small abscess.

A carbuncle forms when multiple inflamed and pus-draining hair follicles combine to create a single infected mass.

Furuncles and carbuncles can be thought of as subtypes of an abscess and appear in areas of hairy skin that are exposed to friction, sweat, or minor trauma, such as underneath the belt or on the front of the thighs, as well as the buttocks, groin, and armpits.

What Causes Abscesses?

Abscesses are caused either by bacteria or an infected hair follicle, although bacteria is the more common cause. Staphylococcus aureus, a type of bacteria that normally exists on the skin and inside the nose, penetrates the body through a hair follicle or punctured or broken skin, like a cut or even a bug bite. In addition, you're more at risk for developing this staph infection if you have:

  • a chronic skin condition, like acne or eczema
  • diabetes
  • a weakened immune system
  • come is close contact with an infected individual
  • poor hygiene habits

Infected hair follicles, known as folliculitis, can cause abscesses to form inside the hair follicle. Follicles become infected if the hair becomes trapped underneath the surface of the skin and can't break through—this is known as ingrown hairs and may happen during shaving. Folliculitis can also occur after swimming in an improperly chlorinated pool or hot tub.

Symptoms & Appearance of Abscesses

An abscess looks like a little bump or a pimple. Over time, however, it can grow to resemble a fluid-filled cyst. The skin surrounding an abscess can also hurt and feel warm to the touch. An abscess that is indurated might feel firm and hard. Depending on what's causing the abscess, other symptoms may be present, including:

  • fever
  • nausea
  • swelling
  • redness and inflammation
  • fluid leakage

How Abscesses Are Diagnosed

A small abscess typically isn't a medical emergency. In fact, it can often be treated with home remedies. If you see a doctor, they should be able to provide a diagnosis based on appearance alone. However, if you have recurring abscesses or if you've tried a remedy yourself and the abscess hasn't responded, you should see a doctor. You should also see a doctor if the abscess:

  • is on your face
  • is one of a few abscesses
  • is extremely painful
  • worsens rapidly
  • you have a fever
  • is more than 2 inches in diameter
  • reappears
  • has persisted for at least 2 weeks

How Abscesses are Treated

Small abscesses can be treated at home with a warm compress to relieve pain and promote drainage. A large abscess needs to be drained to both ease pain and treat the infection. Depending on a number of factors, a doctor will determine whether or not an antibiotic is needed (once the abscess has been drained).

For instance, abscesses that are less than two centimeters in a healthy person generally do not require an antibiotic when drained.

On the flip side, if a person has a weak immune system (for example, a person with diabetes) or if a person has whole-body symptoms like a fever, then one or more antibiotics is usually warranted. 

Unfortunately, the bacterias that cause abscesses have developed a resistance to certain antibiotics. To remedy this problem, a doctor may need to send a sample of the pus to a lab for testing to determine which kind of antibiotic will work most effectively. 

It is important to not try to drain an abscess on your own, otherwise, you could end up worsening the infection.

Also, be sure to thoroughly wash your hands after touching an abscess, and clean anything that has come in contact with it, including clothing and compresses. If the abscess reappears, worsens rapidly, or exhibits any of the signs listed above, see a doctor.

How to Prevent Abscesses

Abscesses are not 100 percent preventable, but there are a few measures you can take to avoid them. For one, always wash your hands and treat any cuts with care—keep them clean, covered, and dry until they heal.

Abscesses are caused by staph infections, and staph infections can be spread person to person and through objects. So don't share personal items like razors, towels, and athletic equipment.

Source:

Baddour LM. (2016). Skin abscesses, furuncles, and carbuncles. In: UpToDate, Post TW (Ed), UpToDate, Waltham, MA. 

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