Boils or pigsa are bacterial skin infections originating deep in the hair follicles. They are generally caused by the bacteria Staphylococcus aureus, but they may be caused by other bacteria or fungi found on the skin's surface. Damage to the hair follicle allows these bacteria to enter deeper into the tissues of the follicle and the tissue underneath. They appear as blister-like swellings filled with pus around the follicle. It occurs most commonly on the face, back of the neck, buttocks, upper legs and groin area, armpits, and upper torso.
Types of boils
- Furuncle. A furuncle can have one or more openings onto the skin and may be associated with a fever or chills. The term furuncle is used to refer to a typical boil that occurs within a hair follicle.
- Carbuncle. The term typically used to represent a larger abscess that involves a group of hair follicles and involves a larger area than a furuncle. A carbuncle can form a hardened lump that can be felt in the skin.
- Cystic acne. A type of abscess that is formed when oil ducts become clogged and infected. Cystic acne affects deeper skin tissue than the more superficial inflammation from common acne. Cystic acne is most common on the face and typically occurs in the teenage years.
- Hidradenitis suppurativa. A condition in which there are multiple abscesses that form under the armpits and often in the groin area. These areas are a result of local inflammation of the sweat glands.
- Pilonidal cyst. A unique kind of abscess that occurs in the crease of the buttocks. Pilonidal cysts often begin as tiny areas of infection in the base of the area of skin from which hair grows (the hair follicle). With irritation from direct pressure, over time the inflamed area enlarges to become a firm, painful, and tender nodule that makes it difficult to sit without discomfort. These frequently form after long trips that involve prolonged sitting.
Red, swollen nodule in skin
Mildly to moderately painful to touch
Usually pea-sized, but may be as large as a golf ball
Other symptoms may include:
Itching before the boil develops
Skin redness around the boil
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