A boil is a skin infection that starts in a hair follicle or oil gland. At first, the skin turns red in the area of the infection, and a tender lump develops. After four to seven days, the lump starts turning white as pus collects under the skin.
- The most common places for boils to appear are on the face, neck, armpits, shoulders, and buttocks. When one forms on the eyelid, it is called a sty.
- If several boils appear in a group, this is a more serious type of infection called a carbuncle.
Causes of Boils
Most boils are caused by a germ (staphylococcal bacteria). This germ enters the body through tiny nicks or cuts in the skin or can travel down the hair to the follicle.
These health problems make people more susceptible to skin infections:
- Problems with the immune system
- Poor nutrition
- Poor hygiene
- Exposure to harsh chemicals that irritate the skin
Symptoms of Boils
A boil starts as a hard, red, painful lump usually about half an inch in size. Over the next few days, the lump becomes softer, larger, and more painful. Soon a pocket of pus forms on the top of the boil. These are the signs of a severe infection:
- The skin around the boil becomes infected. It turns red, painful, warm, and swollen.
- More boils may appear around the original one.
- A fever may develop.
- Lymph nodes may become swollen.
When to Seek Medical Care
- You start running a fever.
- You have swollen lymph nodes.
- The skin around the boil turns red or red streaks appear.
- The pain becomes severe.
- The boil does not drain.
- A second boil appears.
- You have a heart murmur, diabetes, any problem with your immune system, or use immune suppressing drugs (for example, corticosteroids or chemotherapy) and you develop a boil.
- Boils usually do not need immediate emergency attention. However, if you are in poor health and you develop high fever and chills along with the infection, a trip to a hospital's emergency room is needed.
Exams and Tests
Your doctor can make the diagnosis with a physical exam. Many parts of the body may be affected by this skin infection, so some of the questions or exam may be about other parts of your body.