Genetics is thought to be the primary cause of acne in 80% of cases. The role of diet and cigarette smoking is unclear, and neither cleanliness nor exposure to sunlight appear to play a part. In both sexes, hormones called androgens appear to be part of the underlying mechanism, by causing increased production of sebum. Another frequent factor is excessive growth of the bacterium Propionibacterium acnes, which is normally present on the skin.
Your pimples need TLC, too. The study on acne vulgaris found that, in an attempt to dry out acne lesions, patients often use too many products or apply excessive amounts to problem areas, resulting in further irritation and over drying of the skin. Vigorous scrubbing and using harsh exfoliants can make acne worse by rupturing whiteheads and blackheads, turning them into painful red ones. And remember: no matter how satisfying it is, picking and popping your zits will also increase inflammation and opportunity for infection.
Acne appears when a pore in our skin clogs. This clog begins with dead skin cells. Normally, dead skin cells rise to surface of the pore, and the body sheds the cells. When the body starts to make lots of sebum (see-bum), oil that keeps our skin from drying out, the dead skin cells can stick together inside the pore. Instead of rising to the surface, the cells become trapped inside the pore.