Serotonin can help reduce stress; so in that case, serotonin could help those who flare easily in response to stress.
I started taking Lexapro after my second flare went into remission. Lexapro has helped me enormously with social anxieties. I haven't noticed any affect in regard to my flares though. Doesn't mean that it hasn't helped my condition, only that I haven't noticed any benefit in this regard.
Colitis is in remission. No longer get IBS.
Figuring out how to reduce a flare or get into remission is a trial and error experience. Don't expect your GI to have all the answers. He was trained in making diagnoses, prescribing medications, and surgically removing the colon. He was not trained in alternative treatments. That's why they are called alternative treatments.
What works for me: Fecal transplantation, Probiotics, Anti-inflammatory foods, No HFCS, No crystalline fructose, No foods high in fructose, No artificial sweeteners, No pro-inflammatory foods when flaring, vitamins & supplements, Lexapro (for stress).