I don't know that is the case. Some of the studies do suggest improvement (both globally and symptom-based), but you have to be careful how that is interpreted. The gut has its own brain and this is clearly affected by these drugs. Many of these drugs affect serotonin, which is made primarily in the gut for the gut. Serotonin seems to have at least two roles in the gut. One is to make it go (5HT3- and 5HT4) and the other is to sense the gut (5HT3), so if you alter serotonin levels, you alter the activity of the gut. In addition, some of the antidepressants have anticholinergic properties. It now appears that are defects in serotonin processing in the gut and newer drugs such as Alosetron target some of these problems directly.On top of this, the antidepressants can have inhibitory effects on the pain at the brain level. They may also influence one's perception of symptoms. It seems that a lot of the studies on antidepressants have focused on this, for example.Despite this, antidepressants are no cure-all. And the reason for that is clear, other "forms" of IBS probably don't involve serotonin.However, I wouldn't rule out the existing drugs (most of which are not available in the US). Once again, it is difficult to interpret the data for various reasons. Even Kruis' meta-analysis, which seems to say they are not all that good (because of high placebo response) really seemed to display data showing otherwise, although one could argue with that for a variety of reasons.