After using fluorouracil cream, wait 2 hours before applying sunscreen or moisturizer to the treated area. Do not use other skin products including creams, lotions, medications, or cosmetics unless instructed by your doctor to do so.This medication must not be used during pregnancy.It may harm an unborn baby.se this medication as directed by your doctor. Before you apply this medication to the skin, clean the affected area and dry well. Wait 10 minutes, then apply a small amount of medication to the affected skin, using just enough to cover the area with a thin film.