Willow Bark Extract is a source of natural "salicylic acid-like" ingredients which has been shown to contribute effects similar to those seen from synthetic salicylic acid with none of the drawbacks associated with its use, primarily irritation. Willow Bark Extract has been found to increase stratum corneum turnover 2% more so than salicylic acid - 24% as opposed to 22%.
In vitro tests have shown Willow Bark Extract to have activity against Staphylococcus aureus and Propionibacterium acnes, the two strains of bacteria implicated in the formation of acne, as such it may prove useful in targeted facial cleaners, toners and lotion formulas.
It has proven efficacy against gram positive, gram negative bacteria, yeast, and mold.