Home Ingredients Couch Grass (Elymus repens)

Couch Grass (Elymus repens)

Elymus repens (L.) Gould (syn. Agropyron repens (L.) P. Beauv.), rhizoma
Evidence Level
Preliminary
4 Clinical Trials
5 Documented Benefits
1/5 Evidence Score

Couch grass (Elymus repens, long sold as Agropyron repens) is a creeping grass whose washed, dried rhizome is drunk as a tea or taken as a liquid extract to flush the urinary tract. In the EU it is registered only as a traditional herbal medicine: regulators accept its use to increase the amount of urine as an add-on in minor urinary complaints, based on long-standing use alone, and found no well-controlled trial of any couch grass product. The human data are two open liquid extract studies without a control group, a small study in children without blinding, and an unblinded trial of an extract combined with potassium citrate. Animal tests did not confirm that the tea increases urine output, and most other findings come from rats or the lab. People told to limit fluids because of serious heart or kidney disease, pregnant or breastfeeding women and children under 12 should not use it.

Studied Dose No controlled trial of couch grass alone. EU traditional use: 3 to 6 g dried rhizome as tea 2 to 4 times daily (6 to 24 g a day), or 3 to 8 ml liquid extract 2 to 4 times daily, for 2 to 4 weeks with ample fluid. One combination trial used 100 mg dry extract twice daily.
Active Compound Washed, dried rhizome of Elymus repens (Agropyron repens) with the roots removed. It holds about 12% of the fructan triticin, which breaks down in hot water, plus free fructose and glucose, mannitol, inositol, phenolic acids and their esters (including p-coumaric acid hexadecyl ester), caffeoyl and feruloyl quinic esters, small amounts of flavonoids, silica, traces of anthraquinones and a small essential oil fraction. The EMA recognizes no constituent with known therapeutic activity.

Benefits

Traditional use to increase urine flow

The European Medicines Agency accepts couch grass rhizome as a traditional herbal medicine to increase the amount of urine and flush the urinary tract as an add-on in minor urinary complaints, provided enough fluid is drunk. That acceptance rests only on long-standing use of at least 30 years; its reviewers found no well-controlled clinical trial of any couch grass product.

Supported by Trial 3, Trial 1

Urinary comfort reports from open studies without a control group

In a post-marketing study of 313 people with irritable bladder or inflammatory urinary complaints, 32% to 53% were free of symptoms after 12 days of a couch grass liquid extract, depending on the complaint, and an earlier open study in 99 people reported fewer urination complaints. Neither had a comparison group, so the EMA judged both unsuitable for showing that it works.

Supported by Trial 2, Trial 3

Urine output in animal studies

In rats, a cold water extract raised urine output modestly compared with water, but rats drinking a couch grass infusion showed no diuretic effect and no favorable change in urine factors linked to crystal formation. The EMA concluded that no plausible animal data confirm a diuretic effect of the tea, and it found no clinical data on urine output in people.

Supported by Trial 4, Trial 3

Bacterial attachment to bladder cells in lab tests

An acetone extract of the rhizome, and a p-coumaric acid ester isolated from it, reduced attachment of urinary E. coli to human bladder cells in a dish without harming the bacteria or cells, while more water-soluble extracts had no effect. The compound is fat-soluble and present in small amounts, so it may be largely absent from tea, and whether it reaches the urine is unknown.

Supported by Trial 4, Trial 1

Blood sugar and blood fats in rat studies

In rats, a freeze-dried water extract of the rhizome at 20 mg/kg lowered blood sugar after a single dose and over 2 weeks in both normal and diabetic animals, without changing insulin, and lowered triglycerides, cholesterol and body weight in diabetic rats. These are animal results only; couch grass has not been tested for blood sugar or blood fats in people.

Supported by Trial 4

Mechanism of action

1

Fructan-rich rhizome without a recognized active marker

About 12% of the dried rhizome is triticin, a fructan built from roughly 30 fructose units that breaks down in hot or boiling water, alongside free sugars and sugar alcohols such as mannitol. European regulators could not identify any constituent with known therapeutic activity, so there is no marker to standardize products or to track in the body.

2

Flushing depends on the fluid drunk with it

The traditional effect is a flushing of the urinary tract, and the EU monograph states that adequate fluid intake is required for urine volume to increase. Animal tests of the tea did not confirm a direct diuretic action. No pharmacokinetic data exist for any constituent.

3

Phenolic compounds differ between teas and alcohol extracts

Analysis of the rhizome tea found at least 20 phenolic compounds, mainly caffeoyl and feruloyl quinic esters with coumaric, caffeic and ferulic acids, the flavonoid hesperidin, and the amino acid tryptophan. The fat-soluble coumaric acid esters active in lab adhesion tests were found in acetone and other low-polarity solvent extracts, and the EMA notes they may be present in alcohol extracts but not in water teas.

Clinical trials

1
Couch Grass Extract With Potassium Citrate vs Potassium Citrate Alone in Kidney Stone Patients: Unblinded RCT (combination product)
PubMed

Prospective randomized, unblinded trial of a supplement (CalcoMEV) combining 100 mg dry couch grass extract with 24 mEq potassium citrate twice daily, versus potassium citrate 20 mEq three times daily, each with the same diet advice and other medicines chosen by metabolic testing, for 5 months (Brardi et al. 2012, Arch Ital Urol Androl)

50 patients in Italy with kidney stones and one or more metabolic abnormalities that call for potassium citrate, 25 per group; some also took allopurinol, amiloride with hydrochlorothiazide, or pyridoxine.

Stone number (minus 1.0 vs 0.0 stones) and the diameter of the largest stone (minus 3.6 vs 0.0 mm) fell more with the combination, as did urinary uric acid (minus 164.7 vs minus 38 mg/24 h); urinary citrate, oxalate, calcium and pH did not differ. There was no placebo or couch-grass-only arm, the arms got different potassium citrate doses, and the EMA concluded that no conclusion on couch grass itself can be drawn and described the extract as not of pharmaceutical quality. The EMA notes that no adverse events were recorded.

2
Couch Grass Liquid Extract in 313 Users With Urinary Complaints: Open Post-Marketing Study (no control group, not PubMed-indexed)
PubMed

Multicenter post-marketing surveillance study of 50 to 60 drops of a 20% ethanol couch grass liquid extract for 12 days, known only from the summary in the EMA assessment report (Hautmann and Scheithe 2000, Z Phytother; summarized by the EMA)

313 patients with irritable bladder, urethritis, cystitis or prostatitis.

At the end, the share free of symptoms was 32% with irritable bladder, 44% with urethritis, 53% with cystitis and 42% with prostatitis. No side effects were reported. With no control group, the EMA judged that the study met the criteria for a surveillance study but not for assessing efficacy.

3
Couch Grass Liquid Extract in 99 Patients With Urination Complaints: Open Observation (no control group, not PubMed-indexed)
PubMed

Open clinical observation of a 20% ethanol couch grass liquid extract, 60 drops 3 times daily for 28 to 31 days, known only from the summary in the EMA assessment report (Barsom 1981, Erfahrungsheilkunde; summarized by the EMA)

99 patients (87 men, 12 women) with urination complaints linked to prostate enlargement, prostatitis or cystitis.

Urge incontinence, painful or difficult urination, night-time urination and straining were reported as significantly reduced in 44.4% to 100% of patients, urine markers of inflammation normalized, and 96% rated the results good or very good; no adverse effects were recorded. The EMA called it a pilot observation, not a well-controlled study.

4
Couch Grass Extract in Children With Kidney Stones: Small Unblinded Comparative Study (not PubMed-indexed)
PubMed

Two-arm comparative study, described as randomized without stated methods, with no placebo or blinding, of an Agropyron repens extract in capsules dissolved in water at 5 mg/kg versus usual care for 60 days, with ultrasound every 14 days, known only from the summary in the EMA assessment report (Alosy et al. 2019, Indian J Forensic Med Toxicol; summarized by the EMA)

50 children aged 5 to 14 with kidney stones in Iraq, 25 per group; both groups were encouraged to drink water.

Stone number fell in 88% of treated children and in 3 control children, and stone size fell in 23 treated children; colic, blood in the urine and urinary infections were reported as reduced more often with the extract. The EMA noted undefined inclusion criteria, an undescribed control treatment, small size, no blinding and unavailable biochemical data, and judged it not enough to support efficacy.

Side effects and drug interactions

Common Potential side effects

No undesirable effects are known, according to the EU monograph, and none were reported in an observational study of 313 users of the liquid extract, but formal toxicity studies have not been done.
Not recommended for people told to limit fluids, for example with severe heart or kidney disease, because the traditional use depends on drinking plenty of liquid.
Do not use if hypersensitive to couch grass; this is the only contraindication in the EU monograph.
Not recommended during pregnancy or breastfeeding because safety is not established; reproductive, genetic and cancer toxicity tests have not been done, although a liquid extract was negative in one bacterial mutation test.
The EU monograph does not recommend the tea for children under 12 or the liquid extract and tincture for anyone under 18; the extracts and tinctures contain alcohol.
The WHO adverse reaction database held three reports from 2011 to 2020, including two liver injury cases from France in people also taking other herbs and medicines; a causal link to couch grass was not confirmed.
See a doctor if symptoms persist or if fever, painful urination, cramping or blood in the urine appears.

Important Drug interactions

The EU monograph lists no reported interactions, and none have been studied in people; no pharmacokinetic data exist for couch grass.
Prescription diuretics (water pills): any added effect on urine flow is theoretical and unstudied; tell your prescriber before combining them.
Lithium: any increase in urine flow could, in theory, shift lithium levels; a theoretical concern worth raising with the prescriber.
Diabetes medicines: a water extract lowered blood sugar in rats; this has not been studied in people, but monitor blood sugar if you combine them.

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Frequently asked questions about Couch Grass (Elymus repens)

Why does couch grass have so many Latin names?

The plant was long classified as Agropyron repens and has also been called Triticum repens and Elytrigia repens. Botanists later moved it to the genus Elymus, and the International Plant Names Index now uses Elymus repens, while the European Pharmacopoeia still lists the herbal substance as Agropyron repens. These names cover the same plant, and the part used is the washed, dried rhizome with its roots removed.

Has couch grass been tested against a placebo?

No published placebo-controlled trial exists. European regulators found only open studies without a control group and small trials that were not blinded. Two placebo-controlled trials of Renalof, a supplement of couch grass with mannitol and magnesium, are registered as completed, one enrolling 82 adults and one 155, but no results have been posted and no matching paper appears in PubMed.

Does couch grass tea contain the same compounds as an alcohol extract?

Not entirely. Hot water breaks down the fructan triticin, and the tea is rich in caffeoyl and feruloyl quinic esters and other phenolic acids. The fat-soluble coumaric acid esters that reduced bacterial attachment to bladder cells in lab tests came from an acetone extract, and the EMA notes they may be present in alcohol extracts but not in water teas.

Does couch grass tea supply a meaningful amount of silica?

Very little. Dried rhizome collected between June and October contained 0.34% to 0.43% total silicon, and a decoction of 3 g of rhizome in a glass of water was estimated to hold at most about 2.6 mg of absorbable silicon. These figures come from a 1976 analysis cited by the EMA.

Is couch grass sold in multi-herb products?

Often. It appears in traditional Polish tea blends, in a German four-herb tea with birch leaf, giant goldenrod and restharrow, and in an Italian supplement that pairs it with potassium citrate. In lab tests of the German tea, the bacterial anti-adhesion effect came from birch leaf compounds rather than couch grass, and in a rat study of a four-herb blend its own share could not be separated.

What is Couch Grass?

Couch grass (Elymus repens, long sold as Agropyron repens) is a creeping grass whose washed, dried rhizome is drunk as a tea or taken as a liquid extract to flush the urinary tract.

What is Couch Grass used for?

NutraSmarts does not list Couch Grass under a health category. What the research covers: The European Medicines Agency accepts couch grass rhizome as a traditional herbal medicine to increase the amount of urine and flush the urinary tract as an add-on in minor urinary complaints, provided enough fluid is drunk.

What is the recommended dosage of Couch Grass?

No controlled trial of couch grass alone. EU traditional use: 3 to 6 g dried rhizome as tea 2 to 4 times daily (6 to 24 g a day), or 3 to 8 ml liquid extract 2 to 4 times daily, for 2 to 4 weeks with ample fluid. Always follow the product label and check with a healthcare provider for personal advice.

Is Couch Grass safe, and does it have side effects?

Side effects and cautions reported for Couch Grass include: No undesirable effects are known, according to the EU monograph, and none were reported in an observational study of 313 users of the liquid extract, but formal toxicity studies have not been done. It may also interact with some medications. Couch Grass is not right for everyone, so check with a healthcare provider first if you are pregnant or breastfeeding, have a medical condition, or take prescription medication.

Does Couch Grass interact with any medications?

Possible interactions include: The EU monograph lists no reported interactions, and none have been studied in people; no pharmacokinetic data exist for couch grass. Prescription diuretics (water pills): any added effect on urine flow is theoretical and unstudied; tell your prescriber before combining them. If you take prescription medication, check with a pharmacist or doctor before using it.

How strong is the scientific evidence for Couch Grass?

NutraSmarts rates the evidence for Couch Grass as Preliminary (1 out of 5). It is backed by 4 study summaries and 13 cited references summarized on this page. A higher rating reflects more, larger, and better-designed human studies.

References(13 citations)

Evidence ratings on NutraSmarts are based on the totality of human clinical research, with emphasis on randomized controlled trials, meta-analyses, and systematic reviews. The references below directly support claims made throughout this page.

  1. European Medicines Agency, Committee on Herbal Medicinal Products (HMPC). European Union herbal monograph on Agropyron repens (L.) P. Beauv., rhizoma, Revision 1 (EMA/HMPC/114726/2021). European Medicines Agency. 2022;EMA/HMPC/114726/2021. Final, Revision 1, adopted by the HMPC 30 March 2022..SourceUsed to support: Not PubMed-indexed; official EU monograph. Lists couch grass rhizome only under traditional use: a traditional herbal medicinal product to increase the amount of urine to flush the urinary tract as an adjuvant in minor urinary complaints, based exclusively on long-standing use. Gives the doses (tea 3 to 6 g 2 to 4 times daily, 6 to 24 g a day; liquid extract 1:1, 3 to 8 ml 2 to 4 times daily; tincture 1:5, 5 to 15 ml 3 times daily; 2 to 4 weeks), requires adequate fluid intake, does not recommend it where reduced fluid intake is advised, lists hypersensitivity as the only contraindication, no use of the tea under 12 or extracts under 18, not recommended in pregnancy and lactation, no reported interactions, no known undesirable effects, and missing reproductive, genetic and cancer toxicity tests.
  2. European Medicines Agency, Committee on Herbal Medicinal Products (HMPC). Assessment report on Agropyron repens (L.) P. Beauv., rhizoma, Revision 1 (EMA/HMPC/113793/2021). European Medicines Agency. 2022;EMA/HMPC/113793/2021. Final, Revision 1, 30 March 2022..SourceUsed to support: Not PubMed-indexed; the EMA's scientific review. Covers the naming (Elymus repens is the IPNI name; the European Pharmacopoeia keeps Agropyron repens), constituents (about 12% triticin fructan, sugars, mannitol, phenolic esters, traces of anthraquinones), rat data (mild diuresis only with a cold macerate; an infusion did not confirm it), a negative Ames test, and summaries of an open study in 99 patients (Barsom 1981), a post-marketing study in 313 patients (Hautmann and Scheithe 2000), a pediatric comparative study (Alosy et al. 2019) and the Brardi trial. Concludes that no well-controlled trial exists and no constituent with known therapeutic activity can be recognized, and records the WHO database reports and the history of dose changes.
  3. Brardi S, Imperiali P, Cevenini G, Verdacchi T, Ponchietti R. Effects of the association of potassium citrate and agropyrum repens in renal stone treatment: results of a prospective randomized comparison with potassium citrate. Arch Ital Urol Androl. 2012;84(2):61-7..PubMedUsed to support: Unblinded randomized trial in 50 patients with kidney stones: a supplement of 100 mg couch grass dry extract with 24 mEq potassium citrate twice daily, added to standard drug and diet treatment, reduced stone number and size and urinary uric acid more than potassium citrate alone over 5 months; urinary citrate, oxalate, calcium and pH did not differ. A combination product with no placebo or couch-grass-only arm.
  4. Beydokthi SS, Sendker J, Brandt S, Hensel A. Traditionally used medicinal plants against uncomplicated urinary tract infections: Hexadecyl coumaric acid ester from the rhizomes of Agropyron repens (L.) P. Beauv. with antiadhesive activity against uropathogenic E. coli. Fitoterapia. 2017;117:22-27. doi: 10.1016/j.fitote.2016.12.010.PubMedUsed to support: Lab study: an acetone extract of couch grass rhizome (above 250 micrograms per ml) reduced attachment of uropathogenic E. coli to human T24 bladder cells, while more water-soluble extracts did not; the active compound was identified as hexadecyl coumaric acid ester, and the extracts were not toxic to the bacteria or the cells. Not a human study.
  5. Grases F, Ramis M, Costa-Bauzá A, March JG. Effect of Herniaria hirsuta and Agropyron repens on calcium oxalate urolithiasis risk in rats. J Ethnopharmacol. 1995;45(3):211-4. doi: 10.1016/0378-8741(94)01218-o.PubMedUsed to support: Animal evidence only: in Wistar rats on standard, high-carbohydrate or high-protein diets, a couch grass infusion produced no positive effect on the main urinary risk factors for calcium oxalate crystals; the EMA notes this infusion experiment also failed to confirm a diuretic effect.
  6. Eddouks M, Maghrani M, Michel JB. Hypoglycaemic effect of Triticum repens P. Beauv. in normal and diabetic rats. J Ethnopharmacol. 2005;102(2):228-32. doi: 10.1016/j.jep.2005.06.019.PubMedUsed to support: Animal evidence only: an aqueous rhizome extract at 20 mg/kg by mouth lowered blood glucose after one dose and normalized it after 2 weeks in streptozotocin-diabetic rats, and also lowered glucose in normal rats, without changing basal insulin.
  7. Maghrani M, Lemhadri A, Zeggwagh NA, El Amraoui M, Haloui M, Jouad H, Eddouks M. Effects of an aqueous extract of Triticum repens on lipid metabolism in normal and recent-onset diabetic rats. J Ethnopharmacol. 2004;90(2-3):331-7. doi: 10.1016/j.jep.2003.10.011.PubMedUsed to support: Animal evidence only: an aqueous rhizome extract at 20 mg/kg by mouth lowered triglycerides and cholesterol in diabetic rats and reduced their body weight after 2 weeks; in normal rats the triglyceride fall had disappeared by 2 weeks.
  8. Bortolami M, Di Matteo P, Rocco D, Feroci M, Petrucci R. Metabolic Profile of Agropyron repens (L.) P. Beauv. Rhizome Herbal Tea by HPLC-PDA-ESI-MS/MS Analysis. Molecules. 2022;27(15):4962. doi: 10.3390/molecules27154962.PubMedUsed to support: Chemical analysis of couch grass rhizome tea: saccharides, organic acids and amino acids, and at least 20 phenolic compounds, mainly caffeoyl and feruloyl quinic esters, followed by coumaric, caffeic and ferulic acids and the flavonoid hesperidin; tryptophan was identified for the first time. No health outcomes were measured.
  9. Schimmer O, Krüger A, Paulini H, Haefele F. An evaluation of 55 commercial plant extracts in the Ames mutagenicity test. Pharmazie. 1994;49(6):448-51..PubMedUsed to support: Bacterial mutation (Ames) testing of 55 commercial plant extracts with and without liver enzyme activation; couch grass is not among the extracts the abstract lists as active, and the EMA review reports that the couch grass liquid extract (1:1, 20% ethanol) showed no mutagenic potential up to 200 microliters per plate.
  10. Crescenti A, Puiggròs F, Colomé A, Poch JA, Caimari A, Bas J, Boqué N, Arola L. [Antiurolithiasic effect of a plant mixture of Herniaria glabra, Agropyron repens, Equisetum arvense and Sambucus nigra (Herbensurina®) in the prevention of experimentally induced nephrolithiasis in rats]. Arch Esp Urol. 2015;68(10):739-49..PubMedUsed to support: Animal evidence only, in Spanish with an English abstract: a four-herb extract containing couch grass reduced calcium oxalate crystal deposits at 125 mg/kg and kidney microcalcifications at all doses in rats with chemically induced crystal formation, and raised urine output at 125 and 500 mg/kg. Two authors are affiliated with Laboratorios Deiters; couch grass's own share cannot be separated.
  11. Boertz S, Dey M, Herrmann F, Esch S, Sendker J, Dobrindt U, Hensel A. Complex Standard Formulation as an Example for Synergism and Improved Antibacterial Activity Against Uropathogenic Escherichia coli for Urinary Tract Infections. Planta Med. 2025;91(8):419-429. doi: 10.1055/a-2563-7503.PubMedUsed to support: Lab study of a German four-herb tea formulation (birch leaf, couch grass, giant goldenrod, restharrow): the anti-adhesive effect against uropathogenic E. coli came from birch leaf dammarane triterpenes extracted in the presence of goldenrod, not from couch grass; no extract affected bacterial growth. Not a human study.
  12. Sountoulidis P (principal investigator), Aristotle University of Thessaloniki. A Randomized, Double-blind, Placebo-controlled Study of Agropyron Repens, Mannitol and Magnesium Supplement for the Treatment of Calcium Oxalate Upper Urinary Tract Stones: The AMMOS Study (NCT04860492). ClinicalTrials.gov. 2021;NCT04860492. First posted 27 April 2021; last update posted 26 September 2023; completed December 2022; no results posted. Accessed 2026..SourceUsed to support: Not PubMed-indexed (trial registry record). A double-blind, placebo-controlled trial of a couch grass, mannitol and magnesium supplement (Renalof 325 mg) in adults with calcium oxalate stones, enrolling 82 participants; listed as completed, with no results posted and no matching publication found in PubMed.
  13. Catalysis SL (sponsor). Efficacy and Safety of Renalof® in the Removal of Calculi Smaller Than 10 mm Located in the Reno-Ureteral Tract (NCT04695951). ClinicalTrials.gov. 2021;NCT04695951. First posted 6 January 2021; completed October 2020; no results posted. Accessed 2026..SourceUsed to support: Not PubMed-indexed (trial registry record). A randomized, single-blind, placebo-controlled study sponsored by the company Catalysis SL in 155 adults (120 on Renalof 650 mg twice daily, 35 on placebo) for 4 months; listed as completed, with no results posted and no matching publication found in PubMed.