I'm on 4 pills(800mg) a day for 7 days.I wish I could say that this drug is helping but so far it's not. I'm starting to think that since I have IBS-C, perhaps an specific anti-biotic is needed. Now my doctor thinks I'm fool for recommending this treatment but his Zelnorm idea was just as bad for me. I just pray that my breath test is positive so that he'll prescribe me Neomycin. I need an end to this!!! Please read my two posts:Neomycin for eradicating methane-bacteria in IBS-CIBS-C is associated with methane-bacteria.