A carbuncle is a red, swollen, and painful cluster of boils that is a result of a bacterial infection of a hair follicle. Usually single, a carbuncle most likely occurs on the area that is moist and hairy, such as the back of the neck or nape, buttocks, thighs, groin, and the armpits. 

The pus is a mixture of old and white blood cells, bacteria, and dead skin cells. These should drain first before they are able to heal. Carbuncles are also most likely to leave scars. 

Causes

A carbuncle usually develops when Staphylococcus aureus bacteria enter the hair follicles. These bacteria enter the body through broken skin and then cause an infection. These bacteria thrive in moist areas of the body or any area that sweats or experience friction. An active boil or carbuncle is contagious, and can spread to other parts of a person’s body through skin-to-skin contact or sharing of personal items.

Symptoms

• Red, irritated lump under the skin
• The bump and the area around it is usually painful 
• It itches before the lump appears
• Skin crustiness or oozing

Risk Factors

People who are in close contact with someone who has carbuncles may have a higher risk of developing one. The following factors also increase their risk:

• Poor hygiene
• Diabetes
• Weak immune system
• Dermatitis
• Kidney disease
• Liver disease
• Shaving and other activities that break the skin

Other carbuncle symptoms include fever, fatigue, and a feeling of general sickness. Swelling may also occur in nearby tissue and lymph nodes, especially those in the neck, armpit, or groin.

Diagnosis

Doctors usually examine the boil or carbuncle and might suggest sending a sample of the pus for lab testing. This may be useful especially if you have recurring infections or an infection that has not responded to standard treatment. Since many varieties of bacteria that cause boils or carbuncles have become resistant to certain types of antibiotics, lab testing should help determine what type of antibiotic would work best in your situation.

Treatment

The cardinal rule is to avoid squeezing to minimize the risk of complications and severe scarring. Warm compresses may promote the drainage and healing of carbuncles. Apply warm water or a clean, moist and warm washcloth for 20 minutes several times per day. Cry and cover the affected area with a clean dry cloth or gently apply a heating pad for 20 minutes per day.

Also, it is important to wash your hands thoroughly after touching a carbuncle to avoid spreading the bacteria. Clothing, bedding, towels that have touched the carbuncle, should be washed thoroughly as well.

See your doctor if the boils do not drain or heal after treatment with some remedies and warm compresses. Seek medical evaluation of a carbuncle develops on your face, near the eyes or nose or your spine. If the carbuncle has completely drained. antibiotics are usually unnecessary. However, antibiotics treatment may be needed when:

• MRSA is involved and the carbuncle has not completely been drained
• there is surrounding soft tissue infection
• the person who has a carbuncle has a weakened immune system
• an infection has spread to other areas of the body

The doctor will also use one or more of the following to heal your carbuncle completely:

• Antibiotics (which are either taken orally or applied to the skin
• Pain relievers 
• Antibacterial soaps
• Surgery

Important Note: See your doctor if you think you have chronic illness or other skin issues that may be causing breaks in your skin. Never try or use medications that are not prescribed by the doctor.