Emerging treatments

Microbiota-directed therapies

Patients with IBS have significant differences in their microbiota compared with people without IBS, but it is unclear whether this represents cause or effect.[104][105][106] Some randomized placebo-controlled trials report an improvement in IBS symptoms in patients receiving fecal microbiota transplantation (FMT), while other studies report no difference in symptom control between the FMT and placebo groups.[107][108][109][110] FMT can be successfully accomplished with colonoscopy, use of nasojejunal tubes, or pills.

Ramosetron

Ramosetron, a 5HT-3 receptor antagonist, has been shown to be effective in both men and women for reducing diarrhea and abdominal pain in diarrhea-predominant IBS.[111][112] Constipation is a side effect in around 10% of patients.[113] It is approved for the treatment of IBS with diarrhea in several countries, including Japan and India, but not in the US or Europe.

Ondansetron

Ondansetron, a 5HT-3 receptor antagonist, has long been used as an antiemetic. One large prospective study demonstrated that it was modestly effective versus placebo for improving diarrhea and well-being in patients with diarrhea-predominant IBS.[114]

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