Acne involves the over-production of sebum from the sebaceous glands which results in the blockage of the pores with a sticky mass of the dead cells and oil. This creates a breeding ground for the opportunistic overgrowth of bacteria normally present in the skin. These convert the mass into compounds that cause inflammation and unattractive raised surfaces. Skin irritation may also result from the use of artificial cosmetics and even some popular acne products [see Is Bleaching Your Face Really A 'Proactive' Acne Solution?]. The problem is aggravated by pinching, squeezing, scratching or rubbing the skin area plagued with acne.