(Carbuncle; Furuncle; Cutaneous Abscess; Skin Abscess; Abscess, Cutaneous; Abscess, Skin)
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 that is caused by bacteria, sometimes they occur 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
Causes of boils may include:
- Ingrown hair
- Splinter or foreign object lodged in the skin
- Blocked sweat gland or oil duct
Factors that increase your chance of a boil include:
- Poor nutrition
- Poor hygiene
- Weakened immune system
- Exposure to harsh chemicals
- Sports or activities involving close personal contact
A boil may cause:
- Skin lump or bump that is red, swollen, and tender
- Lump that becomes larger, more painful, and softer over time
- A pocket of pus that may form on top of the boil
You will be asked about your symptoms and medical history. A physical exam will be done. 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 from boils may require treatment. These include:
- The boil worsens, continues, 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
The boil can be drained if needed. The infection can be treated with antibiotics.
Home treatment may include:
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. Repeated soaking 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 large, you may need to have it drained or lanced by your doctor.
To help reduce your chance of a boil:
- 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.
- If you have eczema or diabetes, follow the treatment plan outlined by your doctor.
American Academy of Dermatology
Family Doctor—American Academy of Family Physicians
Public Health Agency of Canada
The College of Family Physicians of Canada
Acne. EBSCO DynaMed website. Available at: http://www.ebscohost.com/dynamed. Updated February 24, 2015. Accessed August 5, 2015.
Boils. DermNet NZ website. Available at: http://www.dermnetnz.org/bacterial/boils.html. Updated June 2014. Accessed August 5, 2015.
Hidradenitis suppurativa. EBSCO DynaMed website. Available at: http://www.ebscohost.com/dynamed. Updated March 16, 2015. Accessed August 5, 2015.
Nodulocystic acne. DermNet NZ website. Available at: http://www.dermnetnz.org/acne/nodulocystic-acne.html. Updated February 2014. Accessed August 5, 2015.
Pilonidal disease. EBSCO DynaMed website. Available at: http://www.ebscohost.com/dynamed. Updated February 18, 2015. Accessed August 5, 2015.
Skin abscesses, furuncles, and carbuncles. EBSCO DynaMed website. Available at: http://www.ebscohost.com/dynamed. Updated August 4, 2015. Accessed August 5, 2015.
Last reviewed August 2015 by Michael Woods, 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.