DEAR DOCTOR K: I have a painful boil on my thigh. Can I treat it at home?
DEAR READER: Yes, you can, unless it's an unusually large boil (called a carbuncle). Boils and carbuncles are skin infections that form pus-filled pockets in the skin. Pus is a fluid that contains bacteria, dead skin cells and infection-fighting white blood cells.
A boil begins as a painful infection of a single hair follicle. It is a red, swollen, painful bump under the skin. As the infection worsens, a boil can grow larger. A whitish top (a “whitehead”) can appear at the center of the boil. When that top bursts, the pus will drain out. Boils commonly occur on the buttocks, face, neck, armpits and groin. However, anywhere you have hair, you can get a boil.
A carbuncle is a cluster of interconnected boils. It is a deeper skin infection that involves a group of infected hair follicles in one area. Carbuncles often are found on the back of the neck, shoulders, hips and thighs.
Boils and carbuncles can also cause fever and a general feeling of illness. If you have a fever with a boil, I recommend that you call your doctor. Fevers are unusual with a boil and indicate that the infection may be more serious.
Small boils often drain within five to seven days. You can help this process along by applying a warm, wet washcloth for 20 to 30 minutes, three or four times a day. Once the boil drains, cover it with a clean bandage. Wash the area daily with antibacterial soap to contain the infection. Usually, you won't need antibiotics; your immune system will cure the infection that caused the boil. After all, people have been having boils since human beings first appeared on Earth, and antibiotics have been around for only 70 years.
If you have a carbuncle, a large boil or a boil that doesn't improve after a week of warm compress treatments, call your doctor. Your doctor will drain the infected area through a small incision. This relieves pain, speeds recovery and limits scar formation. You may need to take antibiotics for a carbuncle.
If the infection is deep, your doctor may fill the drained pocket with sterile gauze. The gauze can keep the incision open, allowing pus to continue to drain.
Now and then a boil or a carbuncle leads to a spreading skin infection called cellulitis. If you see the skin around a boil or carbuncle begin to get red and tender, and that red area starts growing, contact your doctor. Cellulitis usually requires antibiotic treatment.
If you have an area of skin that is prone to boils or carbuncles:
Keep the area clean and dry.
Avoid wearing tight clothing.
Wash daily with antibacterial soap.
Use warm compresses at the earliest sign of irritation.
Avoid shaving in that area.
Anthony L. Komaroff, M.D., is a physician and professor at Harvard Medical School. To send questions, go to AskDoctorK.com, or write: Ask Doctor K, 10 Shattuck St., Second Floor, Boston, MA 02115.