A lot of brands do not work because they are not manufactured right.Assuming you get one that is made correctly (after all most of these in nature get from one person's colon to another person's colon so they can make the journey) then there is the problem of getting the right strain as some do more good than others, and gas volume may not be the source of your IBS symptoms, either.I, personally, went from 25-30 farts a day to less than 3 with probioitcs, once I found a brand that actually seemed to have the right bacteria in it. I can't attribute that change to anything else, and the fart frequency goes right back up within the right amount of time (as probiotics tend to be transients rather than permanent residents in the colon) when I stop taking them.I no longer need them every day, but I do reseed from time to time because I really like not having to fart myself to sleep.