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Boil by Mary Calvagna, MS

Definition

A boil is a red, swollen, painful bump under the skin that is caused by an infection. Boils often start in an infected hair follicle. Bacteria form an abscess or pocket of pus. Eventually, the pus may come to a head and drain out through the skin. Boils can occur anywhere, but common sites include the face, neck, armpits, buttocks, groin, and thighs.

There are several types of boils:

Furuncle or carbuncle—an abscess caused by the bacteria Staphylococcus aureus or Streptococcus pyogenes , sometimes occurs as several boils in a group
Pilonidal cyst—an abscess that occurs in the crease of the buttocks almost always require medical intervention
Cystic acne—an abscess that occurs when oil ducts become clogged and infected, more common in the teenage years
Hidradenitis suppurativa —an uncommon disorder where multiple abscesses occur in the armpit and groin area

Pilonidal Cyst

Causes

Causes of boils may include:

Bacteria, including Staphylococcus aureus
Ingrown hair
Splinter or foreign objected lodged in the skin
Plugged sweat gland or oil duct

Risk Factors

Factors that increase your chance of developing a boil include:

Diabetes
Poor nutrition
Poor hygiene
Weakened immune system
Exposure to harsh chemicals

Symptoms

Symptoms may include:

Skin lump or bump that is red, swollen, and tender
Lump becomes larger, more painful, and softer over time
Pocket of pus may form on top of the boil (called "coming to a head")

Diagnosis

The doctor will ask about your symptoms and medical history. A physical exam will be performed. A bacterial culture of the boil may be taken.

Some boils do not need medical attention and may drain on their own. More serious symptoms associated with boils that may require medical attention include:

The boil worsens, persists, or becomes large or severe
You have a fever
The skin around the boil turns red or red streaks appear
The boil does not drain
An additional boil or boils appear
The boil limits your normal activities
The boil is on your face, near your spine, or in the anal area
You have diabetes
You develop many boils over several months

Treatment

Your doctor can drain the boil if necessary and treat the infection with antibiotics.

Home treatment may include:

Warm Compresses

Apply warm compresses to the boil for 20 minutes, 3-4 times a day. Depending on the area of the body affected, you may be able to soak the boil in warm water. These measures can ease the pain and help bring the pus to the surface. Once the boil comes to a head, repeated soakings will help the boil begin to drain.

Lancing the Boil

Do not pop or lance the boil yourself. This can spread the infection and make it worse. If the boil does not drain on its own or it is very large, you may need to have it drained or lanced by your doctor.

Cleaning and Bandaging

Whether the boil drains on its own or was lanced by a doctor, you must keep it clean. Wash it with antibacterial soap and apply a medicated ointment and bandage. Clean the affected area 2-3 times a day until the wound heals completely.

Prevention

To help prevent boils:

Practice good hygiene. Wash boil-prone areas with soap and water or an antibacterial soap. Dry thoroughly.
Clean and treat any minor skin wounds.
Avoid clothing that is too tight.

RESOURCES:

American Academy of Dermatology http://www.aad.org
Familydoctor.org http://familydoctor.org/

CANADIAN RESOURCES:

The College of Family Physicians of Canada http://www.cfpc.ca/
Public Health Agency of Canada http://www.phac-aspc.gc.ca/

References:

American Academy of Dermatology website. Available at: http://www.aad.org . Accessed October 13, 2005.
Hidradenitis Suppurativa. National Institute of Health Library website. Available at: http://www.nlm.nih.gov/medlineplus/hidradenitissuppurativa.html . Accessed July 1, 2008.

Last reviewed September 2009 by Ross Zeltser, MD, FAAD

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