Salicyic Acid - Salicylic Acid causes skin cells to shed quicker than they were doing naturally. This causes the pores to unclog and cleanses the bacteria inside them. As a result this prevents the pores from clogging again in the future, whilst shrinking them in size. In turn, this allows the new cells to grow, promoting healthy skin.
As a result, Salicylic Acid is often used in products aimed at remedying oily or spot-prone skin.
The Acid is also known to be an anti-irritant, antibacterial product that fights acne, and has been "certified" as a safe product by Paula Begoun, in her Cosmetic Ingredient Dictionary. Here's what she has to say about Salicylic Acid:
**Updated by Kat M 01/05/2011**