Dating as far back as ancient Greece, the bark of the willow tree (salix alba) has been revered for its ability to reduce fevers, relieve inflammation, and ease pain. The active ingredient in willow bark is Salicylic Acid, a beta hydroxy acid that exfoliates the skin while acting as an anti-inflammatory. In fact, the anti-inflammatory pain reliever aspirin is made from this same natural source.
The p.Acnes bacterium, which causes acne, thrives in pores that are blocked with dead skin cells, excess oil, and other debris. P.Acnes is anaerobic and microaerophilic, which means that it needs some oxygen, but too much oxygen will kill it. This is how your acne breakouts start- in a pore clogged with oil and blocked off from oxygen by a layer of dead skin cells.
Saliclyic Acid is a Keratolytic (a peeling agent) that powerfully breaks up and dissolves the sticky bonds that hold those excess skin cells to the surface of your skin. Once this outer layer has been chemically loosened and dissolved, your pores are exposed to bacterial-killing oxygen. Even better, oil-absorbing, acne-fighting ingredients, such as Tea Tree Oil, can penetrate the pores and take action.
The anti-inflammatory properties of Salicylic Acid make it the perfect exfoliant for acne-prone skin, which is often easily irritated. When you can fight acne without causing redness, the result is exactly what you want-- clear, glowing skin with fewer acne breakouts.