I never had back pain when I was getting it from a pharmacy because my insurance only covered 4 pills a month and I cut them in half. I had very mild when I started getting them from ADC and taking it a lot more.
For me, the first time I took it it worked. My wife and I were camping without the kids and I took it expecting not much and that it would be like those bogus supplements with names like Alpha Male, Cobra, Panther Pills... you know the ones with the celebrity endorsements. I took the pill and an hour later we went to bed. My life has never been the same.