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Herb library · Herb · Elymus repens (Agropyron repens)

Couch grass (dog grass)

The creeping underground stem of a common, hard-to-kill grass, brewed as a tea to increase the flow of urine. The EMA recognizes that as a traditional use. Studies in people exist but none is controlled, so whether it helps urinary complaints is not known.

Traditional use

Used in European herbal medicine since ancient times (the EMA traces it to Dioscorides and Pliny), mainly in mixtures, as a diuretic. Eclectic physicians in 19th-century America used it for an irritable bladder and painful urination. The EMA accepts it as a traditional herbal medicine to increase urine and flush the urinary tract in minor urinary complaints, based on long use.

What studies show

  • Insufficient

    Minor urinary complaints: the EMA reviewed an uncontrolled observation of 99 patients, a post-marketing survey of 313 patients taking a liquid extract for 12 days (32% to 53% were free of symptoms by the end), and a small unblinded study in 50 children with kidney stones. With no placebo or proper control group, it concluded that no conclusions on efficacy can be drawn.

Be careful of

Cautions

  • ConditionIt only works with plenty of fluid, so the EMA says it is not recommended if your doctor has told you to limit fluids (for example, with serious heart or kidney disease). See a doctor if you have fever, painful urination, cramps or blood in the urine.
  • AmountThe EMA's traditional-use dose for the tea is 3–6 g of the cut root in 250 mL of boiling water, 2 to 4 times a day, for 2 to 4 weeks. Not recommended for children under 12 (tea) or under 18 (extracts and tinctures).
  • PregnancyIts safety in pregnancy and breastfeeding has not been established, and the EMA does not recommend it then.
  • Ask a clinicianTalk with a clinician or pharmacist before using this if you take prescription medicines, are pregnant or breastfeeding, or are giving it to a child.

From the old books

What herbals and dispensaries of the past printed. History, in their words.

“Couch-grass is diuretic and slightly aperient. It is an excellent agent in cases of excessive irritability of the bladder from any cause, lessening the frequency and pain of urination.”
Harvey Wickes Felter and John Uri Lloyd, King's American Dispensatory (1905), vol. 2, p. 2001. See the page of King's American Dispensatory, vol. 2, p. 2001 (opens in a new tab) · Read the full passage from King's American Dispensatory, vol. 2, p. 2001

Sources

  1. European Union herbal monograph on Agropyron repens (L.) P. Beauv., rhizoma — Revision 1 (opens in a new tab) · EMA · read September 25, 2026
  2. Assessment report on Agropyron repens (L.) P. Beauv., rhizoma — Revision 1 (opens in a new tab) · EMA · read September 25, 2026
  3. European Union herbal monograph on Agropyron repens (L.) P. Beauv., rhizoma — Revision 1 (traditional use) (opens in a new tab) · EMA · read September 25, 2026

Reviewed September 25, 2026.