There are many reasons for the appearance of many small bumps with white discharge on the arms, such as folliculitis, keratosis pilaris and so on. 1. Folliculitis: a skin disease caused by bacterial infection. Folliculitis is a purulent inflammation of the entire hair follicle by bacterial infection. Clinical antibiotics are generally used. For example, mupirocin ointment, fusidic acid ointment or 1% neomycin ointment applied externally. At the same time, you can also try ultraviolet irradiation. 2. Perifollicular keratosis: generally pinpoint to corn size skin color to red papules, part of the papule surface with yellowish-white pus, the onset of slight tenderness. The cause of the disease is not very clear, may be related to vitamin A deficiency, genetic factors. Once there are skin bumps with white discharge, please do not self-medicate, need to be treated under the guidance of clinicians to avoid delaying the condition.