Boils and carbuncles are firm, reddish swellings about 5-10 mm across that are slightly raised above the skin surface. They are formed by bacterial infections of hair follicles and surrounding skin. Boils form pustules (small blister-like swellings containing pus) around the follicle and are sore to the touch. A boil usually has a visible central core of pus; a carbuncle is larger and has several visible drainage points. It is deeper and more extensive thana boil.
Boils occur most commonly on the face, back of the neck, buttocks, upper legsand groin, armpits, and upper torso. Carbuncles are less common than singleboils and are most likely to form at the back of the neck.
Boils and carbuncles are common problems especially among adolescents and adults. People who are more likely to develop these skin infections include those with diabetes, alcoholism or drug abuse, poor personal hygiene, jobs or hobbies that expose them to greasy or oily substances, especially petroleum products, and allergies or immune system disorders such as HIV infection.
Boils and carbuncles are caused by Staphylococcus aureus, a bacteriumthat causes an infection in an oil gland or hair follicle. Although the surface of human skin is usually resistant to bacterial infection, bacteria can enter through breaks in the skin. Hair follicles that are blocked by greasy creams or petroleum jelly are more vulnerable to infection. Bacterial skin infections can be spread by shared cosmetics or washcloths, close human contact, or by contact with pus from a boil or carbuncle.
As the infection develops, an area of inflamed tissue gradually forms a pus-filled swelling or pimple that is painful to touch. As the boil matures, it forms a yellowish head or point. It may either continue to swell until the point bursts open and allows the pus to drain, or it may be gradually reabsorbedinto the skin. Boils take between one and two weeks to heal completely afterthey come to a head and discharges pus. The bacteria that cause the boil canspread to other areas of the skin or even into the bloodstream if the skin around the boil is injured by squeezing. If the infection spreads, the patientwill usually develop chills and fever, swollen lymph nodes, and red lines inthe skin running outward from the boil.
Many patients have repeated episodes of boils that are difficult to treat because their nasal passages carry colonies of S. aureus. These bacterialcolonies make it easy for the patient's skin to be reinfected. They are mostlikely to develop in patients with diabetes, HIV infection, or other immunesystem disorders.
Carbuncles are formed when the bacteria infect several hair follicles that are close together. The abscesses spread until they merge with each other to form a single large area of infected skin with several pus-filled heads. Patients with carbuncles may have a low-grade fever or feel generally unwell.
The diagnosis of boils and carbuncles is usually made by the patient's primary care doctor on the basis of visual examination of the skin. For the most part boils and carbuncles are not difficult to distinguish from other skin disorders. S. aureus can easily be cultured in the laboratory if the doctor needs to rule out inclusion cysts or deep fungal infections.
People should not pick at or squeeze boils because of the danger of spreadingthe infection. It is especially important to avoid squeezing boils around the mouth or nose because infections in these areas can be carried to the brain. Keeping the skin clean, washing hands before and after touching the boil orcarbuncle, avoiding greasy cosmetics or creams, and keeping towels and washcloths separate from those of other family members help reduce the spread of bacteria that cause boils.
Boils are usually treated with application of antibiotic creams, such as clindamycin or polymyxin, following the application of hot compresses. The compresses help the infection to come to a head and drain. Carbuncles are usually treated with oral antibiotics, usually dicloxacillin (Dynapen) or cephalexin (Keflex), as well as antibiotic ointments. Patients with bacterial colonies intheir nasal passages are often given mupirocin (Bactroban) to apply directlyto the lining of the nose.
Boils and carbuncles that are very large or that are not draining may be opened with a sterile needle or surgical knife to allow the pus to drain. The doctor will usually give the patient a local anesthetic if a knife is used. Surgical treatment of boils is painful and usually leaves noticeable scars.
In addition to traditional treatment of boils, naturopathic practitioners usually recommend changes in the patient's diet as well as applying herbal poultices to the infected area. The addition of zinc supplements and vitamin A tothe diet is reported to be effective in treating boils. The application of apaste or poultice containing goldenseal (Hydrastis canadensis) root isrecommended by naturopaths on the grounds that goldenseal helps to kill bacteria and reduce inflammation.
Homeopaths maintain that taking the proper homeopathic medication in the first stages of a boil or carbuncle will bring about early resolution of the infection and prevent pus formation. The most likely choices are Belladonna or Hepar sulphuris. If the boil has already formed, Mercurius vivus or Silica may be recommended to bring the pus to a head.
Most boils heal without any problems. Some patients, however, suffer from recurrent carbuncles. Although the spread of infection from boils is relativelyunusual, there have been deaths reported from brain infections caused by squeezing boils on the upper lip or in the tissue folds at the base of the nose.