I used momentasone (nurse calls it MOM) from day 1 of radiation. I used it at least 2 hours before radiation (it was more like 7 hours and at bedtime. I already used Vanicream (because of formaldehyde and other chemical allergies), so I used both products twice daily. I had almost NO skin issues, to my surprise. No rash at all. Minimal discoloration. I am 5 weeks past my final radiation treatment and have had no skin issues. I always get a rash for no reason so by being proactive and using the momentasone and Vanicream early I feel like it worked wonderfully. I had even purchased the chaffing cream recommended by the nurse (which I did not even need)! I had 15 sessions of radiation in total. Good luck!