A pimple on the mouth of the ear hurts when you touch it, consider folliculitis, sebaceous cysts, boils on the external auditory canal, and so on. 1. Folliculitis: folliculitis is more commonly known as bacterial folliculitis, most of which is caused by Staphylococcus aureus infection. Normally, the human body has this bacteria on the top of the skin, and when there is a small wound on the skin, the bacteria will enter the hair follicle and cause infection, which will be manifested as a red pimple centered on the hair follicle, accompanied by itching, tenderness and other symptoms. 2. Sebaceous cysts: the sebaceous gland ducts are blocked, resulting in sebum discharge obstacles, and gradually retained to form a cystic swelling, if the secondary bacterial infection, the acne can appear as a pain when touched. 3. External auditory canal boils: external auditory canal boils are infections of the skin follicles and surrounding tissues in the cartilaginous part of the external auditory canal, most of them are caused by Staphylococcus aureus infections, but also other bacteria or fungi, etc., which are mainly manifested as red and swollen plaques and are accompanied by severe pain in the ear. Pimples on the mouth of the ear hurt when touched may also have other causes, it is recommended to go to the hospital in time, improve the examination to clarify the cause of the disease, give targeted treatment or standardized treatment.