A boil looks like a painful, red bump on the skin that starts small and can grow larger, sometimes more than 2 inches (5 centimeters) in diameter. The skin around the bump is often reddish or purplish and swollen. Over a few days, the bump fills with pus, developing a yellow-white tip that eventually ruptures and drains the pus out. The boil may feel tender and warm to the touch, resembling a water-filled balloon as it fills with pus and dead tissue. It is typically firm at first, then softens as it matures. Boils can range in size from a pea to as large as a golf ball and are usually found in hair- bearing areas prone to sweating or friction, such as the face, neck, armpits, thighs, and buttocks
. Key visual features of a boil include:
- A red or purplish, swollen, painful bump
- A white or yellow pus-filled center or tip
- Surrounding skin redness and swelling
- Possible weeping, oozing, or crusting if the boil drains
Boils differ from pimples and cysts in that they are caused by bacterial infection, tend to be more painful, and contain pus. They also grow faster and are more swollen and tender than cysts or pimples
. In summary, a boil looks like a red, swollen, painful bump with a pus-filled head that eventually ruptures to release pus.
