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. With time, 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 and almost always requires medical treatment
- 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
Copyright © Nucleus Medical Media, Inc.
Last reviewedOctober 2012by Peter Lucas, MD
Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.