If your doctor thinks that you have folliculitis, he or she will examine the skin over your entire body, especially on your arms, legs, buttocks, and scalp. If you are a man, your doctor will also examine the skin of your beard. In general, a doctor will suspect folliculitis if he or she finds hairs in the center of pus-filled pimples (pustules).

If folliculitis is diagnosed and it is severe, your doctor may do testing to find out what is causing the infection. Most cases of folliculitis are caused by bacteria, most commonly by a type called Staphylococcus aureus. It can also be caused by a fungus, such as Candida albicans.

• If your doctor suspects bacteria is causing your infection, he or she may take a sample of the fluid from inside a pustule to identify the type of bacteria. The fluid is sometimes analyzed right at the doctor's office, in which case the results are available immediately.
• To diagnose a fungus, the doctor will take a tissue sample, or biopsy, of the infected area. If fluid or biopsy samples are sent to an outside lab, you will get the results in a few days.