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Mountain knotgrass

Aerva lanata

Also calledSirupeelai (Tamil, Siddha) · Pashanabheda / pashana bedhi, 'stone-breaker' (Ayurveda, Siddha) · Polpala (Sinhala, Sri Lanka) · Bui (India)

In older monographsOuret lanata

A woolly, weedy undershrub of the dry tropics. In Siddha (as sirupeelai) and Ayurveda it is a 'stone-breaker' diuretic for urinary stones and urinary disorders; in Sri Lanka, as polpala, a widely self-prescribed herbal drink. Rat studies support anti-stone and kidney-protective effects. Human evidence is limited to small diuresis studies with conflicting results and a four-patient case series. Ayurvedic practice warns against long-term use, and a rat study found kidney-tubule damage after a month.

What it is used for

  • The main traditional use, as pashanabheda in Ayurveda and sirupeelai in Siddha. In rats with ethylene-glycol-induced calcium oxalate stones, an aqueous suspension (2 g/kg/day for 28 days) lowered oxalate-synthesising enzymes and crystal deposition, and the leaf extract reduced urinary stone risk factors. Isolated quercetin and betulin were also active. In Sri Lankan human studies, polpala drink increased urine volume in one study, while another found no diuresis or change in salt excretion. No trials have tested stone outcomes.1,2,4,5,6

  • An ethanol extract (75–300 mg/kg) reduced blood urea and creatinine in rats with cisplatin- or gentamicin-induced kidney injury. In a four-patient Siddha case series on early diabetic nephropathy, Sirupeelai kudineer was followed by lower urea and creatinine and no reported adverse events. There was no control group. A Sri Lankan rat study found the herb damaged kidney-tubule cells (see safety).1,7,2

  • An extract relaxed isolated goat trachea and, at 30–60 mg/kg by mouth, showed anti-asthmatic and mast-cell-stabilising effects in mice. Extracts also reduced airway inflammation in mice with ovalbumin-induced allergic asthma. Animal work only.1,9

  • An alcoholic extract reduced raised blood sugar by 42–48% in alloxan-diabetic rats (375–500 mg/kg), and repeated dosing for 28 days lowered serum glucose. Animal work only.1

  • Used as a vermifuge for children in Sri Lanka. An ethanolic extract was more active than albendazole against a tapeworm and an earthworm in a laboratory test. There are no human data.1

  • The root is described as demulcent and diuretic for strangury (slow, painful urination). Siddha texts list sirupeelai for urinary disorders (neeradaippu, moothira kiricharam). Not clinically tested for urinary infection.1,7

  • Cough
    Traditional

    Valued for cough in Sri Lanka (Ceylon) and used in Ayurveda for cough and asthma; in Nigeria for cough and bronchitis. No clinical data.1,2,8

  • Headache
    Traditional

    The roots are used for headache in India and in Ayurveda, and the plant for headache in Nigeria. No clinical testing.1,2,8

How it is prepared

infusion

Polpala drink: dried herb steeped in 200 ml of hot water for 15 minutes, then strained.

Gunatilake et al. 2012: 25 g dried herb in 200 ml is the amount Sri Lankan Ayurvedic physicians commonly prescribe (personal communication); Ayurveda does not prescribe it for more than a week.

Kidney stones

decoction

Sirupeelai kudineer: dried whole plant powder boiled in water and reduced to a quarter, made fresh each day.

Parvathy et al. 2024 case-series protocol: 6 g powder boiled in 480 ml water reduced to one quarter; 120 ml twice daily before food for 2–5 weeks.

Kidney disease

Amounts are as recorded by the named source, not a recommendation.

Safety

Pregnancy
Contraindicated
Breastfeeding
Insufficient data

Interactions with medicines

  • diabetes medicinesMinorTheoretical: the extract lowered blood glucose in diabetic rats, so it might add to the effect of glucose-lowering drugs. No human interaction reports.
Interaction checker →

Do not use if

  • Pregnancy or trying to conceive: anti-implantation and pregnancy-failure effects in rats
  • Long-term use: Ayurvedic practice limits use to about a week for fear of urinary-tract damage
  • Existing kidney disease, unless under medical supervision

Toxicity

Oral LD50 in mice was high (22.6 g/kg), but 0.43 g/kg by injection. In a 90-day rat study (40–1000 mg/kg/day orally), the extract altered blood counts, liver enzymes and kidney markers, lowered sperm count, motility and testis weight, and caused mild to moderate cell changes in the brain, kidney and liver. In Sri Lankan rats given polpala infusion for 30 days, standard kidney-function tests did not change significantly, but electron microscopy showed damage to proximal kidney-tubule cells. This supports the Ayurvedic warning against long-term use. In female rats, 200–400 mg/kg caused 20–30% pre-implantation loss and 30–40% pregnancy failure.

In the healing traditions

  • Siddha

    Sirupeelai

    Named in Siddha literature as pashana bedhi ('stone-breaker') and uppu chatthai nasamakki; indicated for thrithodam, urinary disorders (neeradaippu / moothira kiricharam) and anaemia (pandu). Bitter (kaippu) taste and hot potency (veppa veeriyam). Its central action is diuretic; it is said to calm aggravated iyam humour and to aid elimination of metabolic wastes.

    Siddha materia medica as cited in Parvathy et al. 2024

  • Ayurveda

    Pashanabheda (polpala in Sri Lanka)

    Diuretic for lithiasis, with anti-inflammatory, anthelmintic, antibacterial and mild analgesic uses. Also used for cough, asthma and headache, and as an antidote for rat poisoning. Given as a decoction or tea, alone or with other herbs, and traditionally not prescribed for more than about a week.

    Gunatilake et al. 2012; Dinnimath et al. 2017

  • African traditional medicine

    Aerva lanata (Nigeria)

    Lithiasis, headache, renal disorder, vomiting of blood, bronchitis, nosebleed, cough, scorpion stings, fractures and spermatorrhoea.

    Omotoso et al. 2017

Active compounds

ervine, methylervine, aervine, aervoside and related alkaloids
alkaloids reported from the plant
quercetin, kaempferol, isorhamnetin, persinol and persinosides A and B
flavonoids; quercetin isolated and tested in antiurolithiatic models
betulin
triterpene isolated and tested in antiurolithiatic models
lupeol, β-sitosterol, campesterol, chrysin
other constituents reported; composition varies by region

History

Siddha literature calls the plant sirupeelai, the 'stone-breaker' (pashana bedhi), and in Ayurveda it is used as pashanabheda against urinary stones. In Sri Lanka three research groups studied polpala during the 20th century, and work continued because people kept self-medicating with it despite the traditional warning that long use harms the kidneys.

Sources

  1. 1.Goyal M et al. Aerva lanata: a review on phytochemistry and pharmacological aspects. Pharmacogn Rev 2011
  2. 2.Gunatilake M et al. Aerva lanata (Polpala): its effects on the structure and function of the urinary tract. Pharmacognosy Res 2012
  3. 3.GBIF Backbone Taxonomy: Aerva lanata (L.) Juss. ex Schult., synonym of Ouret lanata (L.) Kuntze
  4. 4.Soundararajan P et al. Effect of Aerva lanata on calcium oxalate urolithiasis in rats. Indian J Exp Biol 2006 (abstract)
  5. 5.Selvam R et al. Effect of A. lanata leaf extract and Vediuppu chunnam on the urinary risk factors of calcium oxalate urolithiasis during experimental hyperoxaluria. Pharmacol Res 2001 (abstract)
  6. 6.Dinnimath BM, Jalalpure SS, Patil UK. Antiurolithiatic activity of natural constituents isolated from Aerva lanata. J Ayurveda Integr Med 2017
  7. 7.Parvathy P et al. Treatment of early-stage diabetic nephropathy with Siddha drug Sirupeelai Kudineer: a case series. J Ayurveda Integr Med 2024
  8. 8.Omotoso KS et al. Toxicological evaluation of the aqueous whole plant extract of Aerva lanata. J Ethnopharmacol 2017 (abstract)
  9. 9.Sharif M et al. Immunomodulatory and anti-inflammatory effects of Aerva lanata in ovalbumin induced allergic asthmatic mice. J Ethnopharmacol 2022 (abstract)

Reference, not prescription. Nothing here is medical advice. Herbs can interact with medicines and be dangerous in pregnancy; tell your doctor or pharmacist about anything you take.