A small patch of pimples on the inner side of the lower lip may be ectopic sebaceous glands, lichen planus, herpes, and so on. 1. Ectopic sebaceous glands: Ectopic sebaceous glands are physiologic variations of sebaceous gland development, generally need not be concerned about, and may be manifested as a small patch of pimples on the inner side of the lower lip. 2. lichen planus: a papule is a small solid protuberance on the mucous membrane, the size of a pinhead, usually less than 1 cm in diameter. lichen planus in the oral mucous membrane manifests itself as a typical papule, which arranges itself in the form of bands, plaques and rings. 3. Herpes: Oral unilateral herpes may manifest as a small papule on the inside of the lower lip. A small papule on the inner side of the lower lip may also have other pathologic factors, it is recommended to go to the hospital in time to improve the examination to clarify the cause of the disease, under the guidance of the doctor to give targeted treatment or treatment.