Boils
A boil is a painful, swollen red bump that forms under the skin due to infection, typically starting in an infected hair follicle. The infection causes bacteria to create a pocket of pus, which may eventually drain. Boils can arise anywhere on the body but frequently occur on the face, neck, armpits, buttocks, groin, and thighs. Different types of boils include furuncles, carbuncles, pilonidal cysts, cystic acne, and hidradenitis suppurativa, each characterized by specific causes and locations.
Factors contributing to the development of boils include bacterial infections, ingrown hairs, and plugged sweat glands or oil ducts, with increased risk seen in individuals with diabetes, poor nutrition, poor hygiene, or weakened immune systems. Symptoms typically involve a tender, swollen lump that may produce pus. While some boils can drain on their own, others may require medical intervention, especially if they worsen or are accompanied by fever. Treatment options include warm compresses, drainage by a healthcare provider, and antibiotics if necessary. To prevent boils, maintaining good hygiene and treating minor skin injuries promptly is recommended.
Boils
- ANATOMY OR SYSTEM AFFECTED: Skin
- ALSO KNOWN AS: Carbuncle, cutaneous abscess, furuncle, skin abscess
Definition
A boil is a swollen and painful red bump under the skin that is caused by an infection. Boils often start in an infected hair follicle. Bacteria then form an abscess, or a pocket of pus. Eventually, 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: a furuncle or carbuncle, an abscess caused by the bacteria Staphylococcus aureus or Streptococcus pyogenes, sometimes occurs as several boils in a group; a pilonidal cyst, an abscess that occurs in the crease of the buttocks and almost always requires medical intervention; cystic acne, an abscess that occurs when oil ducts become clogged and infected, more common among teenagers; and hidradenitis suppurativa, an uncommon disorder in which multiple abscesses occur in the armpit and the groin area.
Causes
Causes of boils may include bacteria, an ingrown hair, a splinter or foreign object lodged in the skin, and a plugged sweat gland or oil duct.
Risk Factors
Factors that increase the chance of developing a boil include diabetes, poor nutrition, poor hygiene, a weakened immune system, and exposure to harsh chemicals.
Symptoms
Symptoms include a skin lump or bump that is red, swollen, and tender. The lump becomes larger, more painful, and softer over time, and a pocket of pus may form on the boil (come to a head).
Screening and Diagnosis
A doctor will ask about symptoms and medical history, will perform a physical exam, and may take a bacterial culture of the boil. Some boils do not need medical attention and may drain on their own.
More serious symptoms associated with boils may require medical attention. These serious symptoms include the following: the boil worsens, persists, or becomes large or severe; the patient has 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 the patient’s normal activities; the boil is on the face, near the spine, or in the anal area; the patient has diabetes; and many boils develop over several months.
Treatment and Therapy
A healthcare provider can drain the boil if necessary and treat the infection with antibiotics. Home treatment may include warm compresses (applying warm compresses to the boil for twenty minutes, three to four times a day). Depending on the area of the body affected, the boil can be soaked in warm water. These measures can ease the pain and help bring the pus to the surface. Once the boil comes to a head, repeated soakings will help the boil begin to drain.
Another treatment option is to have a doctor lance the boil, especially if the boil does not drain on its own or is unusually large. The patient should not pop or lance the boil. Doing so can spread the infection and make it worse. Whether the boil drains on its own or is lanced by a doctor, it must be kept clean. One should wash it with antibacterial soap and apply medicated ointment and a bandage. The affected area should be cleaned two to three times a day until the wound heals completely.
Prevention and Outcomes
To help prevent boils, one should practice good hygiene, wash boil-prone areas with soap and water or an antibacterial soap, dry thoroughly, clean and treat any minor skin wounds, and avoid wearing clothes that are too tight.
Bibliography
Beers, Mark H., et al., eds. The Merck Manual of Diagnosis and Therapy. 18th ed. Whitehouse Station, N.J.: Merck Research Laboratories, 2006.
"Boils and Carbuncles." Mayo Clinic, 18 Sept. 2021, www.mayoclinic.org/diseases-conditions/boils-and-carbuncles/symptoms-causes/syc-20353770. Accessed 3 Feb. 2025.
Crossley, Kent B., Kimberly K. Jefferson, and Gordon L. Archer, eds. Staphylococci in Human Disease. Hoboken, N.J.: John Wiley & Sons, 2009.
Turkington, Carol, and Jeffrey S. Dover. The Encyclopedia of Skin and Skin Disorders. 3d ed. New York: Facts On File, 2007.
Weedon, David. Skin Pathology. 3d ed. New York: Churchill Livingstone/Elsevier, 2010.