A pimple on the lip typically occurs due to clogged pores caused by excess oil, bacteria, dead skin cells, and sometimes trapped hair follicles. These clogged pores can lead to inflammation and swelling, forming a pimple. Common triggers include excessive touching of the face, eating foods high in sugar or fat, using oil-based or pore-clogging cosmetics like certain lip balms or lipsticks, not washing the face properly after sweating, hormonal changes (such as those during puberty or menstrual cycles), stress, and certain medications. It is also important to distinguish between a pimple and other lip bumps like cold sores, which are caused by the herpes simplex virus and have different symptoms like tingling or burning sensations.

Preventing pimples on the lips involves maintaining a gentle skincare routine—washing the face twice a day with mild, non-comedogenic products, avoiding harsh scrubbing and excessive face touching, using clean pillowcases, and avoiding expired or clogging makeup products. It is advisable not to pick or pop the pimple to avoid infection or scarring.

In summary, a pimple on the lip results from clogged pores and inflammation due to various external and internal factors, commonly related to hygiene, skincare, diet, and hormonal influences.