The inside of the lips is the lip mucosa, and the appearance of small pimples on the lip mucosa may be caused by diseases such as lichen planus and condyloma acuminatum, as follows. 1. lichen planus: a common chronic inflammatory disease of the oral mucosa, manifested in the oral cavity as typical papules arranged in bands, plaques and rings. 2. warts: for human papilloma virus infection caused by the disease, the initial performance for the local small pimples, can be a pinhead to mung bean size, will gradually increase in size and increase, and to the surrounding spread, the development of papillary, cauliflower-like superfluous organisms. There may be other reasons for the appearance of small pimples on the lip mucosa, it is recommended to go to the hospital in time to clarify the cause of the disease for targeted treatment.