Chronic Diarrhea
Loose stools four or more times a day for more than six months, when prescribed treatment has not worked. In the Han's United cohort, this group includes 1,730 patients and shows the most durable results of any indication: 81.0% improvement at 3 months and 72.3% at 3 years.
What counts as chronic diarrhea
In the study our data is based on, the diagnosis required all four criteria to be present at once. This matters: the definition determines exactly who the percentages apply to.
Diagnostic criteria used in the study
- Frequency
Bowel movements four or more times a day
- Consistency
Unformed stool
- Duration
Symptoms persisting for more than six months
- Prior treatment
Prescribed therapy has not worked
What counted as a treatment outcome
- Cure — stool frequency and character returned to normal
- Marked improvement — stool frequency dropped to two or three times a day
- Outcomes were assessed at 3, 12, and 36 months after the course
The role of the microbiome
- About 100 trillion microorganisms live in the human gut
- They take part in digestion, immunity, and maintaining the gut barrier
- When the balance is disrupted, diversity declines, beneficial bacteria decrease, and pathogens increase
- The guideline describes FMT as a reset of the gut ecosystem, not a one-time medication
When conventional treatment hasn't helped
The study included specifically those patients whose prior therapy had not worked — this is one of the conditions for the diagnosis.
FMT is a next step, not a substitute for a workup. The cause of the diarrhea needs to be established by a doctor first.
Why FMT
The guideline on intestinal microbiota transplantation describes four mechanisms behind how the method works.
Flora replacement
Beneficial bacteria competitively suppress pathogenic ones
Metabolic restructuring
Synthesis of short-chain fatty acids is restored, pH is regulated
Immune regulation
Pro-inflammatory factors decrease, immune balance is restored
Barrier restoration
Intestinal wall permeability decreases, fewer toxins enter the bloodstream
Mechanism of action
After extraction and purification, a healthy donor's microbiota is transplanted into the patient's gut to restore the disrupted balance of the intestinal microecosystem. The guideline emphasizes: this is a transplant of beneficial microbial communities, not a simple transfer of intestinal contents.
What this means for chronic diarrhea
- Addresses the disrupted composition of the microbiome, not just the symptom
- Course-based treatment: one session a day, six sessions make up a course
- In the study, the result lasted longer than for other indications
- If there is no response, a repeat course or a change in strain type is possible
What the research showed
The primary source of these figures is an analysis of 15,000 cases conducted at Shanghai Tongji University-affiliated Tenth People's Hospital and published in 2025.
81.0%
Improvement at 3 months
1,730
Patients with chronic diarrhea in the cohort
72.3%
Improvement maintained at 3 years
15,000
Total study cohort
Evidence base
- Analysis of 15,000 cases (2025): 1,730 patients with chronic diarrhea. Improvement of 81.0% at 3 months, 78.1% at 12 months, 72.3% at 36 months
- Durability of the result: among the nine disease groups in the study, chronic diarrhea loses effect the slowest — for most of the other groups, the percentage drops noticeably more by the three-year mark
- Safety over three years of follow-up: no serious adverse reactions were recorded, no cases of infection transmission were identified, and no link was found between FMT and the emergence of new diseases
- Chinese expert consensus, 2022: diarrhea associated with microbiota disruption and infectious diarrhea are included in the list of indications for FMT
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How these percentages were calculated
The caveats here matter more than the numbers themselves — we give them in full
- The study is retrospective and descriptive. There was no control group: it contains no comparison with untreated patients.
- The percentages are calculated from those who reached the follow-up point, not from all participants. Across the whole cohort, by three years, 6,218 of the 15,000 people remained under observation, so the decline in percentage reflects both the fading of the effect and dropout from follow-up.
- This is the proportion showing improvement, not cure. For chronic diarrhea, a marked effect was defined as stool frequency dropping to two or three times a day; cure meant complete normalization.
- The average age of participants was 45. This is data on adult patients.
Source: Tian Hongliang, Wang Le, Ma Chunlian, et al. Chinese Journal of Gastrointestinal Surgery, 2025, 28(3): 296-303.
Related conditions
FMT is also used for other bowel disorders
Ulcerative Colitis
510 Han's United patients, 64.3% improvement at 3 months. Active clinical trials.
Crohn's Disease
Inflammatory bowel disease. Part of the IBD cohort (510 Han's United patients).
IBS
1,940 Han's United patients, 70.6% improvement at 3 months.
Functional GI
8,258 constipation patients — 70.3% improvement. Largest group in the Han's United cohort.
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Has diarrhea lasted more than six months?
Send your medical history and test results — a doctor will check whether your case fits the criteria used to select patients, and will tell you honestly if FMT won't help here.
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