The white stuff squeezed out from inside the acne is sebum, keratin plugs and other substances, which usually accumulate in the mouth of the hair follicle and will form acne. The secretion of sebaceous glands is regulated by sex hormones. Increased levels of androgens or an imbalance between male and female hormones after puberty can increase the size of sebaceous glands and the secretion of sebum. Sebum provides an anaerobic environment for the growth of Propionibacterium acnes within the hair follicles to provide oil and the pathogen hydrolyzes the triglycerides within the sebum to free fatty acids, which stimulates proliferation of keratinocytes at the follicle ducts and over-keratinization of keratinocytes. Skin hyperkeratosis, so that sebum excretion is blocked, when sebum, keratin plugs, etc. accumulate in the mouth of the hair follicle, acne will be formed, so after squeezing the acne, the discharge of white stuff is sebum, keratin plugs and other substances. It is recommended that patients who have acne should not directly squeeze the acne with their hands to avoid secondary infection and delay treatment.