Skin cancer: Has anybody had fluorouracil treatment?

My parent has hit the point where she gets four or five pre-cancerouas growths on her face every year. The doctor has been freezing them off with good results.

The Dr. recently suggested she apply a fluorouracil lotion to her face two times a day for two weeks. Apparently, this kills off the defective skin cells and holds down the development of the pre-cancerous growths for about two years. But, my mom is worrying about the redness and unpleasnt effects of the treatment during the 2 to 3 weeks she is dealing with it.

Can anybody who has used this treatment pass on their experience. She wants to hear from people who have done the treatment.
Thanks.