Why do挤出的粉刺 (popped pimples) smell bad?

The expelled pimples may emit a foul odor, mainly due to possible infection within the pimple and the oxidation and denaturation of sebum. Specifically, pimples result from localized blockage caused by abnormal keratinization of the sebaceous gland duct, leading to poor sebum secretion and its subsequent accumulation within the pores. When bacteria such as Propionibacterium acnes infect the area, they break down the sebum and produce gases with a rancid or foul smell, such as hydrogen sulfide. Additionally, if sebum remains accumulated in the pores for a prolonged period, it can undergo oxidation and denaturation, further intensifying the odor of the pimples. Therefore, when squeezing pimples, one may notice a distinct unpleasant smell. To avoid this situation, it is recommended to maintain clean skin and refrain from squeezing pimples manually to prevent worsening the infection. Furthermore, appropriate medical treatments or cosmetic procedures can be employed to improve pimple-related issues.