A boil is a red, swollen, painful bump under the skin that is usually 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
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Causes of boils may include:
- Bacterial invasion
- 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:
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 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 may 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. This is all most boils need to get better.
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 area heals completely. Try and keep the wound open by soaking or ointment to avoid it filling up with pus again.
Antibiotics may be needed if you have:
- Evidence of more severe infection
- Diabetes or other chronic illness
- A weakened immune system
- No improvement with lancing
- A lot of boils
To help reduce your chances 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, diabetes, or other chronic disease, follow the treatment plan outlined by your doctor.
American Academy of Dermatology https://www.aad.org
Family Doctor—American Academy of Family Physicians https://familydoctor.org
Public Health Agency of Canada http://www.canada.ca
The College of Family Physicians of Canada http://www.cfpc.ca
Acne. EBSCO DynaMed Plus website. Available at: https://www.dynamed.com/topics/dmp~AN~T115279/Acne . Updated June 27, 2017. Accessed August 17, 2017.
Boils. DermNet New Zealand website. Available at: https://www.dermnetnz.org/topics/boils. Updated January 2016. Accessed August 17, 2017.
Hidradenitis suppurativa. EBSCO DynaMed Plus website. Available at: https://www.dynamed.com/topics/dmp~AN~T115217/Hidradenitis-suppurativa . Updated August 9, 2016. Accessed August 17, 2017.
Nodulocystic acne. DermNet New Zealand website. Available at: https://www.dermnetnz.org/topics/nodulocystic-acne. Updated February 2014. Accessed August 17, 2017.
Pilonidal disease. EBSCO DynaMed Plus website. Available at: https://www.dynamed.com/topics/dmp~AN~T114205/Pilonidal-disease . Updated January 30, 2017. Accessed August 17, 2017.
Skin abscesses, furuncles, and carbuncles. EBSCO DynaMed Plus website. Available at: https://www.dynamed.com/topics/dmp~AN~T116747/Skin-abscesses-furuncles-and-carbuncles . Updated July 31, 2017. Accessed August 17, 2017.
- Reviewer: EBSCO Medical Review Board Michael Woods, MD, FAAP
- Review Date: 09/2018
- Update Date: 09/03/2014