A boil is a red, swollen, painful bump under the skin. It often starts in an infected hair follicle. Bacteria form an abscess or pocket of pus. Boils can occur anywhere. They are most common on the face, neck, armpits, buttocks, groin, and thighs.
There are several types:
- Furuncle or carbuncle—come from staph infections, may occur in a group
- Pilonidal cyst—forms in the crease of the buttocks
- Cystic acne—occurs when oil ducts become clogged and infected
- Hidradenitis suppurativa—a rare condition with multiple abscesses in the armpit and groin area
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Causes of boils may be:
- Bacteria invading an area
- Ingrown hair
- A splinter or object stuck in the skin
- Blocked sweat gland or oil duct
Things that raise the risk of a boil are:
- Health conditions such as:
- Poor hygiene
- Injury with open wounds
- Exposure to harsh chemicals
- Sports or activities with close contact
A boil may cause:
- A red, swollen, tender skin lump
- A lump that gets bigger, more painful, and softer
- A pocket of pus— on top of the boil
The doctor will ask about your symptoms and health history. A physical exam may be done. The boil may be swabbed and tested for bacteria.
Treatment depends on the severity of the boils and if there are other health problems. Some boils drain on their own. Others can spread and cause serious problems.
Options may be:
- Home care, such as:
- Applying warm compresses or soaking the boil in warm water
- Cleaning the boil, applying ointments, and bandaging
- Medical treatment, such as:
- The doctor makes an incision and drains the boil
- Antibiotics—for those with certain problems or health conditions
To lower the risk of a boil:
- Wash the skin daily with soap, then dry thoroughly.
- Clean and treat any minor skin wounds.
- Do not wear clothing that is too tight.
- Be sure to manage eczema, diabetes, or other long-term diseases.
Acne. EBSCO DynaMed website. Available at:https://www.dynamed.com/condition/acne . Accessed January 29, 2021.
Boils. DermNet New Zealand website. Available at: https://www.dermnetnz.org/topics/boils. Accessed January 29, 2021.
Hidradenitis suppurativa. EBSCO DynaMed website. Available at: https://www.dynamed.com/condition/hidradenitis-suppurativa . Accessed January 29, 2021.
Nodulocystic acne. DermNet New Zealand website. Available at: https://www.dermnetnz.org/topics/nodulocystic-acne. Accessed January 29, 2021.
Nowicka D, Grywalska E. Staphylococcus aureus and host immunity in recurrent furunculosis. Dermatology. 2019;235(4):295-305.
Pilonidal disease. EBSCO DynaMed website. Available at: https://www.dynamed.com/condition/pilonidal-disease. Accessed January 29, 2021.
Skin abscesses, furuncles, and carbuncles. EBSCO DynaMed website. Available at:https://www.dynamed.com/condition/skin-abscesses-furuncles-and-carbuncles . Accessed January 29, 2021.
Last reviewed September 2020 by
EBSCO Medical Review Board
Shawna Grubb, RN
Last Updated: 2/24/2021