Sulfur, the active ingredient in this mask, is one of the oldest acne treatments known. Yes, sulfur smells bad (rotten eggs come to mind), but it is effective. The nice part is tha you don't have to leave the mask on your face very long (that'll just dry your skin out)- put it on a damp face after cleansing, brush your teeth, pet your dog, and wash it right off. The sulfur in this mask is antibacterial (the root cause of acne), improves cell turnover to speed up healing of old pimples/scars, and dries out existing blemishes. Used a couple times a week for active breakouts and maybe once a week for effectual prevention of new pimples, this product has earned a place in my acne fighting arsenal.