A boil is a common, painful infection of a hair follicle and the surrounding skin. It begins as a red lump, then fills with pus as white blood cells rush in to fight the infection. Good home care can often clear up a single boil, also known as a skin abscess.

What causes a risen bump?

Most boils are caused by Staphylococcus aureus, a type of bacterium commonly found on the skin and inside the nose. A bump forms as pus collects under the skin. Boils sometimes develop at sites where the skin has been broken by a small injury or an insect bite, which gives the bacteria easy entry.

How long does a risen bump last?

Boils may take from 1 to 3 weeks to heal. In most cases, a boil will not heal until it opens and drains. This can take up to a week. A carbuncle often requires treatment by your healthcare provider.