i own one but don't use it. if you read the info that comes with it, it doesn't work on all acne. see if you can google up any info. sorry i can't be of more help. the main point of zeno is to use it as soon as you feel one developing and it's not a miracle worker (like i assumed). the acne apparently just goes away after repeated treatments. my sister uses it and she's happy, i'm not. maybe it's me.