Abscesses (AB-seh-sez) are localized or walled-off accumulations of pus * caused by infection that can occur anywhere within the body. Furuncles (FYOOR-ung-kulz), which are also known as boils, and carbuncles (KAR-bung-kulz) are types of abscesses that involve hair follicles * and occur on the skin.
An abscess develops when the body's immune system * isolates an area of body tissue that has been infected by an invading microorganism * (usually bacteria) to prevent the infection from spreading further. The body sends infection-fighting leukocytes (LOO-kuh-sites) to the infected area. Leukocytes are specialized white blood cells that can destroy infectious microorganisms such as bacteria, parasites, and viruses.
As the bacteria and white blood cells clash at the site of infection, pus begins to form within the involved tissue. As the infection progresses, a wall of tissue develops around the infection site, forming an abscess. A growing abscess on the skin is usually warm, red, painful, and swollen with pus.
Abscesses that grow inside the body are uncommon but can be very serious. Internal abscesses can occur anywhere within the body: some of the more common areas where they form include the area around the appendix * (as when someone has appendicitis [ah-pen-dih-SY-tis], an inflammation of the appendix); the area around one of the tonsils * (a peritonsillar [per-ih-TON-sih-lar] abscess); and in the gums or jaw (a dental abscess). They may also form in the liver, around the spinal cord, or on or in the brain. People who have weak immune systems, such as those who have had chemotherapy * treatment for cancer or someone with diseases such as long-standing diabetes * or HIV * /AIDS * , are at greater risk of developing internal abscesses.
Furuncles (boils) are a type of skin abscess most commonly found on the face, neck, armpit, groin, buttocks, and thighs. Carbuncles are larger areas of skin infection made up of several boils that have formed close together and then joined. They take longer to form and are often located on the back and the nape of the neck. Men are more likely to develop carbuncles than are women. Fever and a general feeling of illness are often associated with carbuncles.
Bacteria that are commonly found on the skin, especially Staphylococcus aureus (stah-fih-lo-KAH-kus ARE-ree-us) and Group A β-hemolytic * Streptococcus (BAY-tuh he-muh-LIH-tik strep-tuh-KAH-kus), are typically the cause of most abscesses, furuncles, and carbuncles. People who have staphylococcal bacteria residing in their nose (called staph colonization) may be prone to developing recurrent skin abscesses.
Much of the skin's surface is covered by hair. At the base of each hair is a hair follicle, a sac-like pit in which the hair shaft develops and grows. If the skin around a hair follicle has been damaged in some way, such as with a cut or a nick on the skin from shaving, bacteria on the skin's surface can enter and start to cause an infection. This invasion triggers the body's immune system, which walls off the area around the infected hair follicle. As the body's defenses go to work, the area fills with pus and becomes inflamed. When an area of skin contains infected, inflamed hair follicles, the condition is known as folliculitis (fuh-lih-kyoo-LYE-tis).
A boil usually starts within an area of folliculitis. The growing pus inside the boil creates pressure and swelling around the infected spot, often forming a drainage point at the surface of the skin called a head. A carbuncle typically has many small areas where pus has collected and formed heads.
Abscesses that appear inside the body, such as within the abdomen, may be caused by types of bacteria different from those that cause skin infections. For example, an abscess that forms with appendicitis may be caused by a blockage in the appendix (known as a stone). These abscesses usually contain bacteria normally found inside the intestine and in bowel movements. A liver abscess can occur when an infection in the abdomen spreads, or when an infectious agent from somewhere else in the body travels through the bloodstream and is deposited in the liver.
Abscesses are not contagious, but the bacteria that cause them can spread from person to person and can cause other types of infections. Individuals who touch a boil that is draining pus should wash their hands. Clothes, washcloths, and towels that have touched an open or draining boil or carbuncle should not be shared.
Skin abscesses sometimes need to be drained before they can heal, although most of the time they heal on their own without medical treatment. Skin abscesses are often treated at home by applying warm compresses. The abscess usually comes to a head on its own, then begins to drain and heals soon afterward.
Boils and carbuncles that do not drain on their own should not be squeezed or lanced (cut open) to remove pus by anyone but a health care provider. Trying at home to puncture a boil could force the infection deeper into the skin and spread the bacteria. Skin abscesses that do not improve on their own will need to be lanced by a doctor to prevent the infection from becoming worse. The area is thoroughly cleaned before it is lanced, and antibiotics are sometimes prescribed. Most carbuncles require antibiotic treatment.
Internal abscesses are usually treated with surgical drainage and antibiotics. If a dental abscess is not treated with antibiotics, it can destroy the root of a tooth, leading to the need for a root canal * procedure or the removal of the entire tooth.
Keeping the area around a minor skin wound clean and dry, not sharing razors, and using antibacterial soap can help prevent skin abscesses.
See also Appendicitis • Mouth Disorders: Overview • Staphylococcal Infections • Streptococcal Infections • Tonsillitis
Esposito, Lisa, ed. Skin Health Information for Teens: Health Tips about Dermatological Disorders and Activities That Affect the Skin, Hair, and Nails. 3rd ed. Detroit, MI: Omnigraphics, 2013.
MedlinePlus. “Skin Abscess.” U.S. National Library of Medicine, National Institutes of Health. http://www.nlm.nih.gov/medlineplus/ency/article/000863.htm (accessed June 1, 2015).
Merck Manuals. “Folliculitis and Skin Abscesses.” http://www.merckmanuals.com/home/skin-disorders/bacterial-skin-infections/folliculitis-and-skin-abscesses (accessed June 4, 2015).
American Osteopathic College of Dermatology. 1501 East Illinois St., PO Box 7525, Kirksville, MO 63501. Toll-free: 800-449-2623. Website: http://www.aocd.org (accessed July 9, 2015).
* pus is a thick creamy fluid, usually yellow or ivory in color, that forms at the site of an infection. Pus contains infection-fighting white cells and other substances.
* hair follicles (FAH-lih-kulz) are the skin structures from which hair develops and grows.
* immune system (im-YOON SIStem) is the system of the body composed of specialized cells and the substances they produce that helps protect the body against disease-causing germs.
* microorganism is a tiny organism that can be seen only by using a microscope. Types of microorganisms include fungi, bacteria, and viruses.
* appendix (ah-PEN-diks) is the narrow finger-shaped organ that branches off the part of the large intestine in the lower right side of the abdomen. Although the organ is not known to have any vital function, the tissue of the appendix is populated by cells of the immune system.
* tonsils are paired clusters of lymphatic tissue in the throat that help protect the body from bacteria and viruses that enter through a person's nose or mouth.
* chemotherapy (KEE-mo-THER-apee) is the treatment of cancer with powerful drugs that kill cancer cells.
* diabetes (dye-uh-BEE-teez) is a condition in which the body's pancreas does not produce enough insulin or the body cannot use the insulin it makes effectively, resulting in increased levels of sugar in the blood. This condition can lead to frequent urination, dehydration, weight loss, weakness, and a number of other symptoms and complications related to chemical imbalances within the body.
* HIV or human immunodeficiency virus (HYOO-mun ih-myoono- dih-FIH-shen-see) is the virus that causes AIDS (acquired immunodeficiency syndrome).
* AIDS or acquired immunodeficiency (ih-myoo-no-dih-FIH-shensee) syndrome is an infection that severely weakens the immune system; it is caused by the human immunodeficiency virus (HIV).
* hemolytic (he-mo-LIT-ik) refers to the destruction of red blood cells with the release of hemoglobin into the bloodstream.
* root canal is a procedure in which a dentist cleans out the pulp of an infected tooth, removes the nerve, and then fills the cavity with a protective substance.