Folliculitis is a skin disease that occurs when the sebaceous glands secrete a lot of oil, blocking the pores and preventing the normal secretions from being excreted, which then leads to local inflammation, followed by bacterial or fungal infection, and the formation of follicular inflammation. It occurs at the back of the head because the local secretion of oil is more likely to lead to folliculitis. In addition to the head, it can also occur on the front and back of the head where the sebaceous glands are particularly developed and oil secretion is high. In cases like this, an aggressive anti-infection treatment approach should be taken. The first step is to determine whether the infection is fungal or bacterial, and to choose different drugs for different causes in order to achieve twice the result with half the effort. I hope to visit the dermatology clinic first, and then choose antifungal, or antibacterial drugs for treatment.