There IS proof that SSRI's, TCA's and other antidepressants help with the symptoms of IBS though - I believe that the disorder has to do with a faulty brain-gut loop somehow, because of this. For those that don't know, the gut does contain quite a bit of serotonin-receptors, for instance, which can then obviously be DIRECTLY AFFECTED by swallowing an SSRI.
However, as I understand it, your response to various drugs is dependent on which TYPE of IBS you have, so not every AD-med' is equal here, you gotta' pick the right one. (I suppose the others have far less PERIPHERAL effects...? and are more selective towards the brain itself - a bit like how you can have antihistamines which work on both mind and body - which in that case is often bad - you want it either for sleep or for runny nose, not both - this could be something similar)
American Gastroenterological Association Institute Guideline on the Pharmacological Management of Irritable Bowel Syndrome
http://www.gastrojou...1089-0/fulltext
"A systematic review of multiple RCTs of 6- to 12-week duration showed a modest improvement in global relief and abdominal pain in patients treated with tricyclic antidepressants, although the overall body of evidence was low quality."
American Gastroenterological Association Institute - Technical Review on the Pharmacological Management of Irritable Bowel Syndrome
http://s3.amazonaws....Association.pdf
Hmm... let's have a look at the Tricyclics, and see what we can find... IF you want to try something quickly though, which is sort-of tricyclic, and currently undergoing trials for the treatment of specificaly IBS, then get some Tianeptine - it should be mentioned that some find Tianeptine activating and therefore helpful with fatigue.
The same could be said for the true tricyclics, wherein many of them have significant norepinephrinergic reuptake inhibition action. (similar to an SNRI, like Duloxetine)
All right... let's see...
https://www.ncbi.nlm...les/PMC2669938/
"We suggest using TCAs with the least anticholinergic effects (i.e. doxepin and desipramine) for elderly patients or constipation-predominant IBS and imipramine or amitriptyline for diarrhea-predominant IBS and patients with insomnia. Larger comparative trials with strict surveillance on compliance are needed to elaborate the role of antidepressants in standard practice."
Well, there you have the info! = ) What type of IBS do you concur with, in the description? Constipation or diarrhea? Would some of your problems with fatigue perhaps best be battled by one of the more noradrenergic ones?
On another note - there's a FODMAP, aka Food Map -app these days, which lets you check various food-stuffs if they elicit responses in IBS - the first list is only generic though, and not entirely correct for you as a person, but you can also eventually build a vast cartography of specific substances which are ok for just YOU to digest.
I have a friend with IBS, and I've been nagging her to actually get a grip on this, since she's been complaining for years - eventually she started using the app and now her symptoms have significantly lessened, since now she can double-check not just individual ingredients, but specific dishes as well! = )