Hi Marci - 

Lotions with salicylic acid in them have been around for more than 20 years and used for a variety of skin conditions including that problem on the back of your daughter's arms (keratosis pilaris).  They are very safe, little or none is absorbed into the blood stream, and the flu shot won't interact with the lotion. Try the lotion at night on her acne too.  As long as she doesn't get irritated, it should improve her acne.  If she's not better in 8 weeks, go back to see her dermatologist.

Foods are a tough one.  I really like kids to stay away from junk food like sugary sodas, anything deep fried, most snack foods (a good one is Sun Chips) because they are full of cheap fat and carbs.  Try to get her hooked on things like apples or bananas dipped in penut butter or honey or thin slices of ham or whole wheat toast with a yummy jam, etc.  But ............ I have no proof that diet affects acne!

Your welcome!  Dr. I