This immune reaction will cause the puss to fill up the infected tissue surrounding the hair follicle. The inflammation of the surrounding tissue, coupled with the accumulating puss will cause a large, smooth, reddish, and painful bump filled with pus.
It is referred to as a carbuncle when multiple hair follicles in close proximity all get infected and form multiple boils. Although similar, boils are still different from pimples the latter only affect the sebaceous gland and its immediate surrounding area. The boil, on the other hand, goes as deep as the hair follicle, affecting a larger area. Therefore, boils cause a larger, more painful, puss-filled bump.
Stages of a Boil
There are several stages of a boil: the initial infection, the inflammation, the swelling, and the drainage and healing. Here are those stages.
1. Initial infection
In this stage, there is a bacterial infection of the hair follicle. It occurs if the hair follicle is damaged, usually through excessive pulling, twisting, or minor injuries like shallow cuts and scrapes.
Once the bacteria have entered the hair follicle, it will start building-up and infect the surrounding tissue as well. This infection will lead to inflammation and cause pain.
Out of all the stages of a boil, this will be the most noticeable because the infection will cause the body to react and defend itself. White blood cells will flood the area to fight the bacterial infection. And so after a few days to a week, you may see some swelling under the skin and the formation of a large whitehead.