Small pustules growing on the lips of the mouth lips can be caused by problems such as acne, and inside the mouth can be caused by problems such as mouth ulcers. 1. acne: generally refers to hair follicles, sebaceous glands of a chronic inflammatory skin disease, manifested as whiteheads, blackheads, pimples, pustules, nodules, and other symptoms, you can use minocycline, doxycycline, isotretinoin, clindamycin cream, erythromycin cream and other medications for treatment. 2. oral herpes: generally due to viral infections caused by oral mucosal diseases, herpes simplex is the most common, manifested as congestion and edema, pain is obvious, affecting eating, small pustules on the mouth and other symptoms, you can use acyclovir, vasiclovir and other drugs for treatment. Small pustules on top of the mouth need to go to the hospital as soon as possible to confirm the diagnosis, and standardized treatment under the guidance of medical advice.