There are many causes of pimples on the chest, such as folliculitis, acne, skin boils and so on. 1. Folliculitis: Folliculitis is an acute skin inflammation, mainly due to the inflammatory reaction caused by the blockage of hair follicles, the lesions are mainly located around the hair follicles, which can be manifested in localized small pimples, redness and swelling, which can cause the phenomenon of a lot of pimples on the chest. 2. Acne: Acne is a chronic skin inflammation, which may be related to inappropriate, irregular life and other factors, and may also be due to infection with Propionibacterium acnes. 3. Skin boils: Skin boils are inflammation that occurs deep in the hair follicles and can cause localized redness, swelling, heat and pain in the acute stage of the disease, and even the formation of more serious abscesses. There are many reasons why there are a lot of pimples on the chest, and it is recommended to go to the hospital in time to improve the examination after the symptoms appear, to clarify the cause of the disease, and then follow the doctor’s instructions to carry out standardized treatment, and not to do it on their own, so as not to lead to adverse consequences.