An infection of a hair follicle is called a furuncle or a boil. When a hair follicle becomes infected, the surrounding skin is infected as well, forming a pus-filled bump or lesion that can be tender or painful. In some cases, many hair follicles in the same area can become infected, which is called a carbuncle. Furuncles and carbuncles are rarely serious.
Furuncles are most often the result of a bacterial infection, most often Staphylococcus aureas, according to the National Institutes of Health. They can also be caused by other bacteria or fungi. The infection develops when the bacteria or fungi are able to enter the body because a hair follicle is damaged. Once the microbes enter the follicle's deep tissue and the surrounding subcutaneous tissue, the infection can develop.
An infected hair follicle often begins as a small bump, but it soon grows larger and more painful as it fills with pus. The surrounding skin can be red, and the center may develop pustules, according to the National Institutes of Health. The lesion can ooze or drip and may begin to crust over. Other symptoms that can accompany a boil include a fever and fatigue. The skin may also feel itchy before the furuncle begins to form.
Hair follicle infections can develop in anyone. However, people with medical conditions such as diabetes or illnesses that compromise the immune system are more prone to boils, according to MayoClinic.com. People who have close contact with someone with boils can also develop the infection. When boils form, they are most common on the face, neck, thighs, armpits and buttocks.
In many cases, hair follicle infections heal on their own without medical intervention. Generally, the boil will grow until it bursts and drains and then finally heals, usually within two weeks. Once a furuncle begins to drain, it's important to exercise good hygiene to prevent the infection from spreading to other follicles, according to the National Institutes of Health. Clean and dress the boil frequently.
A doctor can drain the boil by making an incision in the lesion and removing the pus. Although this is not usually necessary, it can speed the healing process and prevent scarring. In cases of recurrent infections, your doctor may prescribe antibiotics.