Do I once again need to experience irritation, peeling etc as I did when first using .04 or can I do the switch to retin-a .1 so gradually that I don't experience that and yet it is still working? I have sun damage, precancerous spots. Am 67 with some wrinkles & combination skin- experience some breakouts. The .04 was not irritating after awhile, did not stop some of the precancerous spots although stopped some. Using .1 every other night, spf 30 daytime, now in cold weather 2hr a day.