Salicylic Acid

Salicylic acid, better known as BHA (beta hydroxy acid), exfoliates by breaking down the bonds that hold dead skin cells to the surface, rather than by scrubbing them away. Because it dissolves in oil rather than water, it can travel into the oil filled lining of a pore and clear buildup from the inside, which is why it's particularly effective against blackheads and whiteheads.

The FDA classifies salicylic acid as an approved over the counter acne treatment at concentrations between 0.5% and 2%. Its usefulness goes beyond acne, though: by clearing away surface buildup, it can also soften the look of dullness, uneven tone, and other visible signs of aging.

Two things set it apart from a physical scrub. First, it has hydrating qualities that help offset the drying effect exfoliation can sometimes have. Second, it carries natural calming properties, so it can actually help soothe skin that's already irritated rather than aggravate it further.