OK guys i use niacin on a daily basis using the flush free...sometimes before an arms workout ill use the regular version where you get the huge vascularity and feel like your skin is burning etc...so i used it last wk and i got ridiculous veins, hot flashes etc, and it worked great!! i used it again on my carb day before arms about 45 minutes before and it did nothing, im confused how this happened, im planning on using it before i go onstage but i dont know why i didnt get the flush effect the other day, any ideas????