I tried DA for about 3 weeks on one per day and then upped my dose to 2 per day for a further 2 weeks and i'm afraid to say it didn't seem to make any difference for me.
Like Lil says, it's worth a shot tho as we are all different and it might help you.
I am usually IBS-C. I've been on Miralax, Lactulose, Zelnorm, you name it. AFter the Zelnorm stopped working, I am now on a combination of DA-IBS, plus Phazyme, plus Milk of Mag., for a little over a month now.
I take 2 DA's, one in the morning and one before bed. The Phazyme is to help with the gas, so I take one midmorning and one after dinner. The Milk of Mag I take one tbsp. in the morning and one tbsp after dinner.
I was supposed to be on this combo until this month when the Amitiza is available. However, I've decided not to go with the Amitiza now because this other way is working! The main plus of this is that all three products that are working are also all OTC. I like this.
Good luck, I'd suggest trying it out, but maybe with 2 instead of one.