I have tried B5 from GNC and it did not work AT ALL - not to mention they are very expensive. It's a poor quality brand. I have been using a very good brand of B5 and have noticed a big difference in my cystic acne. I've been on it for three weeks and it is very inexpensive, especially considering the quality of it. I bought mine from:
www.b5clearskin.com
If you don't have really bad Acne you will probably notice a difference in a week or so. I have (had) REALLY BAD cystic Acne and in three weeks I have noticed a HUGE difference in my skin. I am so happy it is working for me.