External abscesses resemble pus-filled pimples or boils, whereas internal abscesses look like swollen bumps with raised and inflamed edges.

An abscess can form anywhere in the body, both externally and internally, and has a typical appearance depending on the body part where it is formed.

• On the skin: Initially, it looks like a pimple, boil, or an insect bite but later, turns into a red, swollen lump, warm and tender to touch and filled with pus.
• Under the skin: A painful swollen bump with raised and inflamed edges (cellulitis).

What is an abscess?

An abscess is a collection of pus on or under the skin that results due to an infection caused by bacteria (Staphylococcus aureus and Streptococcus pyogenes). Rarely, a parasitic infection may cause abscess development.

A sterile abscess is when an abscess develops due to a foreign body in the tissue.

12 risk factors that can make someone more likely to develop an abscess

Here are 12 risk factors for the development of an abscess:

1. Diabetes
2. Immunocompromised due to cancers, steroid therapy, as well as immunosuppressants
3. Cancer lesion itself may present as an abscess
4. Inflammatory bowel disease
5. Obesity
6. Smoking
7. Weak immune system (human immunodeficiency virus infection and acquired immune deficiency syndrome, tuberculosis)
8. Chronic skin conditions, such as eczema or psoriasis
9. Hospital-acquired infections
10. Chemotherapy
11. Severe burns
12. Foreign body trapped in the tissue

What causes an abscess?

Abscesses are often a result of activation and response of the immune system to a bacterial infection of an open wound or a trapped foreign object.

An open wound or a cut allows the entry of bacteria (most common), fungi, and parasites, which activates the immune system, leading to the infiltration of white blood cells to fight the infection. These living or dead white cells along with debris (remnants of cells) collect in the wound, making pus and resulting in a painful abscess.

Apart from invading bacteria, other causes of an abscess include:

• A foreign object, such as a bullet, a thorn, or a piece of metal
• Infection of the surgical site
• A puncture wound
• Opportunistic infections in immune-deficient conditions
• Blocked oil or sweat gland

9 types of abscesses

1. Skin abscess:
   • Open wounds or cuts infected by bacteria (most often staphylococcus)
   • Folliculitis (hair follicle infection)
   • Boils and injuries that get infected
   • Can form anywhere in the body
2. Dental abscess:
   • It can form due to infection through a cavity caused by tooth decay, broken or cracked teeth
   • Often forms in the tooth pulp (center part of the tooth) and spreads to the roots
3. Abdominal abscess:
   • Can occur in organs, such as the liver, pancreas, kidneys, and the intestines
   • A result of infections of abdominal organs and irritable bowel disease
4. Anorectal abscess:
   • Occurs in or near the anus
   • Most commonly form due to sexually transmitted diseases, anal fissures, or injury to the area
5. Liver abscess:
   • Amoebic liver abscess: An abscess due to amebiasis (caused by a parasite called Entamoeba histolytica), which is an intestinal infection that has spread to the liver.
   • Pyogenic liver abscess: A pus-filled area on the liver, caused by abdominal infections or trauma to the liver.
6. Brain abscess:
   • A medical emergency caused by bacterial or fungal infection in the brain
7. Bartholin abscess:
   • Typically occurs in the Bartholin glands, located on each side of the vaginal opening due to blockage of the Bartholin gland
8. Epidural abscess:
   • Caused by infection of the meninges (coverings of the brain and the spinal cord)
   • If an abscess is formed inside the skull, it is called an intracranial abscess
   • If an abscess is formed in the spine, it is called a spinal epidural abscess
9. Peritonsillar abscess:
   • A complication of tonsillitis

What are the symptoms of an abscess?

Symptoms may vary depending on the location and the underlying disease causing the abscess, but may include:

• Pain
• Redness
• Swelling
• Warmth and tenderness on touch
• Oozing of pus or blood

Other accompanying symptoms may include:

• Fever with chills
• Fatigue
• Loss of appetite
• Enlarged and palpable lymph nodes

How is an abscess treated?

Treatment varies depending on the size, location, and severity of the abscess, but may include:

• Incision and drainage:
  • The area around the abscess is numbed using a local anesthetic medication.
  • A small cut is made to drain the pus.
• Antibiotics: A large abscess (more than 5 cm) needs a proper course of antibiotics before and after the surgical drainage.

How do you drain an abscess at home?

One can try to drain abscess at home only if the abscess is small (less than 1 cm).

• Apply a warm compress to the affected area for 30 minutes many times a day so that it drains on its own.
• Make sure to wash hands before and after the compress.
• Avoid puncturing or squeezing the abscess; it may lead to further spread of infection.

When to see a doctor

Seek medical help if:

• An abscess is not healing even after a good home treatment
• It is becoming more painful
• Redness and swelling are increasing
• It is increasing in size (more than half an inch)
• There is fever with chills
• A person has uncontrolled diabetes or underlying comorbid conditions