Okay - so I've never seen any data on this so I'm guessing.  If you put the moisturizer on first, let it absorb for 5-10 minutes and then use the Renova, it may dilute it just a hair but not enough to make a clinical difference.  I know from many years of experience myself and with my patients that the Renova still works very, very well.  It's also less irritating, so you're more likely to keep using it and use it more often. Maybe that's the key.  Dr. I