Benefits
Loose-stool duration in a 40-child placebo-controlled trial
In a double-blind trial in Russia, 40 children aged 3 months to 7 years in hospital with rotavirus infection took a tormentil tincture (3 drops per year of age, 3 times daily, up to 5 days) or a look-alike placebo. Loose stools lasted 3 days versus 5 on placebo, and less IV fluid was needed. It has not been repeated, and EU regulators do not recommend tormentil under 18.
Traditional European use for mild, short-lived loose stools
The European Medicines Agency's herbal committee accepts tormentil rhizome as a traditional herbal medicine for relief of mild diarrhea in adults, taken as a tea, tincture, liquid extract or dry extract. This rests on long-standing use; the committee judged the clinical data preliminary and not enough for well-established use. It advises seeing a doctor if symptoms last over 3 days.
Loose-stool duration with a tannin and chamomile sachet in children
In an open-label Italian trial, 60 children with acute gastroenteritis took oral rehydration solution with or without a sachet product (Actitan F) of tannins from agrimony and tormentil plus chamomile flavonoids for 7 days. Loose stools lasted a median 5 days with the sachet and 4 days without, not a significant difference. Stool counts at 24 hours did not differ between groups, and the maker funded the study.
Bowel symptom scores in an open-label adult dose-finding study
In Germany, 16 adults with active ulcerative colitis took an ethanolic tormentil extract at 1,200, 1,800, 2,400 and 3,000 mg a day, 3 weeks each, with 4-week breaks. At 2,400 mg a day the median activity score fell from 8 to 4.5 and CRP from 8 to 3 mg/L, and scores rose again during breaks. There was no control group, so this does not show an effect.
Gut bacteria and tannin breakdown in lab studies
When tormentil extracts were incubated with human stool samples, gut bacteria broke down catechin and its oligomers, in one study produced urolithins from its ellagitannins, and favored the growth of short-chain fatty acid producers (Ruminococcaceae), raising bacterial diversity. These are lab findings with stool samples, not results in people.
Mechanism of action
Astringent tannin content
Some commercial tormentil rhizomes measured above 20% tannins and related polyphenols, and tinctures above 2%, led by procyanidin B3, procyanidin C2 and agrimoniin. The EMA assessment considers the astringent effect of these tannins to make the traditional use for loose stools plausible, though this has not been measured directly in people.
Tannins stay in the gut rather than entering the blood
In the 16-patient study, no tannins or tannin breakdown products were found in blood samples even at 3,000 mg a day. In a human gut-cell model, condensed tannins mostly stayed bound to the cell surface and only triterpenes passed through, so any action is likely local in the gut.
Gut bacteria turn ellagitannins into urolithins
Human stool bacteria formed urolithins A, B and C from a tormentil rhizome extract, and urolithins tested in human immune cells grown in the lab lowered the inflammatory signal TNF-alpha. Whether this happens to a useful degree in people taking tormentil is unknown.
Antioxidant activity in the lab
Tormentil scavenged superoxide and peroxyl radicals in cell-free tests and reduced oxygen radical release from colon biopsy tissue taken from patients with active ulcerative colitis. These are test-tube and tissue findings, not effects measured after taking tormentil by mouth.
Clinical trials
Randomized, double-blind, placebo-controlled trial at a children's infectious disease hospital in St. Petersburg, Russia. Per the EMA assessment, the study product was a 1:10 tincture in 40% ethanol and the placebo an alcohol extract of tea matched for look and taste. (Subbotina et al. 2003, Pediatr Infect Dis J)
40 children aged 3 months to 7 years with rotavirus diarrhea (20 tormentil, 20 placebo); 3 drops per year of age, 3 times daily, until diarrhea stopped or for up to 5 days.
Diarrhea lasted 3 days with tormentil versus 5 days with placebo (P < 0.0001), and 8 of 20 children versus 1 of 20 were diarrhea-free 48 hours after admission. The tormentil group needed smaller volumes of IV fluids. No side effects were reported (per the EMA assessment). The EMA noted this tincture is weaker than EU products and has no documented EU use, and does not recommend tormentil for children.
Pilot, randomized, open-label (no placebo) trial at the University of Naples, retrospectively registered (NCT03356327); the sachet combined tannins from agrimony and tormentil with chamomile flavonoids, and the maker, Aboca, funded the study and donated the products. (Russo et al. 2018, Ital J Pediatr)
60 children with acute gastroenteritis of under 7 days and mild to moderate dehydration; 30 took the sachet (1 sachet every 4 hours, up to 4 a day, for 7 days) plus oral rehydration solution, 30 took rehydration solution alone.
Median duration of diarrhea was 5 days with the sachet and 4 days with rehydration alone (P = 0.48), so the main outcome did not favor the sachet. Median stool count after 24 hours was 3.5 versus 4, not a significant difference (P = 0.4); only the fall from baseline within the sachet group was significant. Most children in the sachet group (23 of 30) stopped the rehydration solution after day 1. No adverse events were reported. Tormentil's own share of any effect cannot be judged.
Open-label, uncontrolled, dose-escalating study at University Hospital Freiburg, Germany, of an ethanolic dry extract (tannin content 15 to 22% per the EMA assessment), each dose for 3 weeks followed by a 4-week washout. (Huber et al. 2007, J Clin Gastroenterol)
16 adults with active ulcerative colitis (clinical activity index 5 or higher), taking 1,200, 1,800, 2,400 and 3,000 mg a day in turn.
At 2,400 mg a day, median activity index fell from 8 to 4.5 and CRP from 8 to 3 mg/L; the index fell in all patients on treatment and rose again during washouts. No tannins were found in blood. Six patients (38%) had mild upper abdominal discomfort; the EMA assessment reports mild digestive symptoms in 62% and one hospitalization for worsening colitis. Without a control group, the effect cannot be separated from natural fluctuation.
In vitro study testing six herbal remedies used by people with inflammatory bowel disease in cell-free radical tests and on inflamed colon biopsies, compared with 5-ASA. (Langmead et al. 2002, Aliment Pharmacol Ther)
Colorectal biopsies from patients with active ulcerative colitis; no one took tormentil by mouth.
Tormentil scavenged superoxide and peroxyl radicals in a dose-dependent way and reduced oxygen radical release from the inflamed biopsies, as did most of the other herbs. The authors called for formal trials. Test-tube results do not show what happens after the herb is swallowed.