What's the most effective way to treat carbuncle?

Boil or abcess. The word carbuncle, is an old fashioned name for a boil or abcess. This is a skin infection caused by the staph aureus bacteria. You may have one boil, or many, and others in your house may have boils as well, because this germ is very contagious. Some people continue to get boils for months or years, since the germ may be hiding on their body. A single carbuncle can be treated by surgery.
Heat Sometimes. Sometimes applying hot compresses frequently will bring it to a head and allow for spontaneous drainage. Do not lance it yourself because of a higher risk of more infection and scarring!
Drainage. Incision and drainage will release pus, allow infection o resolve and relieve pain from pressure.