Boils and carbuncles

Boils and carbuncles.

Definition:
Boils and carbuncles are painful, pus-filled bumps that form under your skin when bacteria infect and inflame one or more of your hair follicles.

Boils (furuncles) usually start as red, tender lumps. The lumps quickly fill with pus, growing larger and more painful until they rupture and drain. A carbuncle is a cluster of boils that form a connected area of infection under the skin.

You can usually care for a single boil at home, but don't attempt to prick or squeeze it — that may spread the infection. Call your doctor if a boil or carbuncle is extremely painful, lasts longer than two weeks or occurs with a fever.

Symptoms:

Boils
Boils can occur anywhere on your skin, but appear mainly on your face, neck, armpits, buttocks or thighs — hair-bearing areas where you're most likely to sweat or experience friction. Signs and symptoms of a boil usually include:

• A painful, red bump that starts out about the size of a pea
• Red, swollen skin around the bump
• An increase in the size of the bump over a few days as it fills with pus (can sometimes reach the size of a golf ball)
• Development of a yellow-white tip that eventually ruptures and allows the pus to drain out.

Once the boil drains, the pain usually subsides. Small boils usually heal without scarring, but a large boil may leave a scar.

Carbuncles
A carbuncle is a cluster of boils that often occurs on the back of the neck, shoulders or thighs. Carbuncles:

• Cause a deeper and more severe infection than single boils do
• Develop and heal more slowly than single boils do
• Are likely to leave a scar

Signs and symptoms that may accompany carbuncles include:

• Feeling unwell in general
• Fever
• Chills

When to see a doctor
You usually can care for a single, small boil yourself. But see your doctor if you have:

• A boil on your face or spine
• A boil that worsens rapidly or is extremely painful
• Boils that are very large, haven't healed in two weeks or are accompanied by a fever
• Frequent boils
• A condition that suppresses your immune system, such as an organ transplant, corticosteroid use or an HIV infection
• Recently been hospitalized

Children and older adults who develop one or more boils also should receive medical care.

Causes:
Boils usually form when one or more hair follicles — the tube-shaped shafts from which hair grows — become infected with staph bacteria (Staphylococcus aureus). These bacteria, which normally inhabit your skin and sometimes your throat and nasal passages, are responsible for a number of serious diseases, including pneumonia and endocarditis — an infection of the lining of your heart. They're also a major cause of hospital-acquired infections.

Staph bacteria that cause boils generally enter through a cut, scratch or other break in your skin. As soon as this occurs, specialized white blood cells called neutrophils rush to the site to fight the infection. This leads to inflammation and eventually to the formation of pus — a mixture of old white blood cells, bacteria and dead skin cells.


Complications:
Complications of boils and carbuncles are generally few, but can be serious. They include:

• Blood poisoning. In some cases, bacteria from a boil or more commonly, a carbuncle, can enter your bloodstream and travel to other parts of your body. The spreading infection, commonly known as blood poisoning (sepsis), can lead to infections deep within your body, such as your heart (endocarditis) and bone (osteomyelitis). Blood poisoning itself — which is characterized by high fever, rapid breathing and elevated heart rate — can lead to septic shock, a life-threatening state of extremely low blood pressure.
• MRSA. Another potentially serious problem is the emergence of drug-resistant strains of Staphylococcus aureus. Up to half of the staph bacteria found in hospitals are resistant to many commonly used antibiotics, including methicillin. Methicillin-resistant staphylococcus aureus (MRSA) has led to the use of alternative antibiotics, such as vancomycin, but some strains of staph bacteria have become less susceptible to vancomycin, too. Although MRSA is often acquired in a hospital setting, it can be spread in the general community, as well.

Treatments and drugs:
You can generally treat small boils at home by applying warm compresses to relieve pain and promote natural drainage.
For larger boils and carbuncles, treatment usually includes draining the boil with an incision and sometimes taking antibiotics:

• Incision and drainage. Your doctor may drain a large boil or carbuncle by making a small incision in the tip. This relieves pain, speeds recovery and helps lessen scarring. Deep infections that can't be completely drained may be packed with sterile gauze so that pus can continue to drain.
• Antibiotics. Sometimes your doctor may prescribe antibiotics to help heal severe or recurrent infections, or infections that may be caused by MRSA.