I was skeptical about using this stuff. I never believed it would work this fast. It took 3 days for my one cat to have her acne totally gone from her chin. My older cats acne was worse. Her fur around one side of her mouth was gone and she had the dark looking stuff right under her chin. The dark stuff is almost gone and the mouth area is getting better and better. The fur is starting to fill back in too! I HIGHLY recommend this for feline acne.