Have tried devil's claw before, but this was the first time I found a reasonable concentration that would allow me to reach the levels of active ingredient used in studies. No side effects, but no dramatic effects on my aches and pains noted. Ramped up from 2-per-day to 4-per day over three weeks. Will continue until bottle gone, then will quit for a while to see if I note a difference. Kind of hard being your own control subject. Thinks this is about the best value out there. If the herb works for you, this is the one to get.