Restharrow

Metadata

Etymology note: The English name “restharrow” derives from “rest” (arrest/stop) and “harrow” (plough), referring to the plant’s deep, tough, woody roots that were notorious for entangling and halting horse-drawn ploughs. Dioscorides and Pliny described its use for urinary complaints in the first century AD, and Galen noted its effect on increasing urine flow and reducing urinary stones. Medieval herbalists reasoned that if the plant could “break” a farmer’s plough, it could also “break” stones in the body — a classic example of the Doctrine of Signatures influencing herbal tradition.

Approved Indications

Commission E (Germany)

• Approved: Irrigation therapy for:
  • Inflammatory diseases of the urinary tract
  • Prevention and treatment of kidney gravel (Nierengruess)
• Daily dose: 6-12 g of the drug or equivalent preparations

ESCOP

• Listed (monograph published in 2003 2nd edition; revised 2015): Irrigation of the urinary tract, especially in cases of:
  • Inflammation of the lower urinary tract
  • Renal gravel
  • Adjunctive therapy in bacterial urinary tract infections
• Note: ESCOP includes restharrow in its monograph series, though the level of endorsement is based on traditional use documentation rather than clinical trial evidence

EMA/HMPC (Traditional Use)

• Traditional herbal medicinal product (EMA/HMPC/138319/2013, finalized 2014):
  • To increase the amount of urine to achieve flushing of the urinary tract as an adjuvant in minor urinary complaints
  • For use in adults and adolescents over 12 years of age
• Classification: Traditional use only (not “well-established use”) — meaning the indication is based on at least 30 years of safe use (including 15 years within the EU), not on clinical trial evidence
• A revision 1 of the monograph was under consultation as of 2025

Agreement/Disagreement

• Good agreement between Commission E, ESCOP, and EMA/HMPC on the core indication: irrigation therapy for urinary tract inflammation and kidney gravel
• Commission E wording is the most expansive (“prevention and treatment of kidney gravel”)
• EMA/HMPC is most conservative (“minor urinary complaints”)
• All three bodies base their assessments primarily on traditional use, not clinical trial data
• US/Anglophone: Virtually unknown in mainstream medicine; not recognized by FDA or US clinical guidelines; the concept of “irrigation therapy” itself is absent from US practice

Conditions Treated

• Irrigation therapy for urinary tract inflammation (primary approved indication)
  • Inflammatory conditions of the lower urinary tract
  • Adjunctive support during bacterial UTIs (supportive flushing, not primary antimicrobial therapy)
• Kidney gravel prevention and treatment
  • Prevention of renal gravel formation
  • Support for passage of small urinary calculi
• Traditional uses (not formally approved):
  • Gout and rheumatic complaints (empirical use documented in older sources)
  • Skin conditions (folk medicine)

Role in Blasen- und Nierentees (Bladder and Kidney Teas)

Restharrow root occupies a central position in the German tradition of Blasen- und Nierentees — combination herbal teas designed for urinary tract flushing therapy. These teas typically combine several aquaretic and anti-inflammatory herbs, and restharrow has been a standard ingredient for centuries. The EMA/HMPC has even published a separate monograph on “Species diureticae” (diuretic tea combinations) recognizing this tradition.

Common combination partners in traditional Blasen- und Nierentees include:

A notable commercial combination product is Aqualibra, which combines restharrow root extract with Java tea (Orthosiphonis folium) and goldenrod herb (Solidaginis herba) for urinary tract complaints. All three component herbs have individual EMA/HMPC monographs.

Mechanism of Action

Primary Mechanisms

1. Aquaretic Effect (Mild Diuretic)

   • Increases urine volume without significant electrolyte loss (aquaretic rather than true saluretic diuretic)
   • The mechanism is not fully elucidated but is multifactorial
   • The essential oil and isoflavonoid content are believed to contribute to the diuretic action
   • Animal studies have confirmed diuretic activity, but no human clinical trials have formally measured this effect

2. Inhibition of Renal Hyaluronidase-1 (Hyal-1)

   • A more recently proposed mechanism: isoflavonoids from restharrow root inhibit human hyaluronidase-1, an enzyme involved in renal fluid regulation
   • Hyal-1 degrades hyaluronic acid in the kidney, contributing to water reabsorption; inhibition of this enzyme may promote aquaresis
   • The isoflavanone sativanone showed 61.2% inhibition of Hyal-1 at 250 micromolar concentration
   • Other active isoflavonoids: onogenin (25.4%), medicarpin (22.4%), and calycosin-D (23.0%) inhibition at the same concentration
   • This mechanism provides a molecular rationale for the traditional aquaretic use, though it has only been demonstrated in vitro
   • [Source: Addotey et al. 2018, Fitoterapia 130:169-174, PMID: 30176279]

3. Anti-inflammatory Activity

   • Dichloromethane extract (rich in isoflavonoids and triterpenes) inhibits IL-8 and TNF-alpha release from LPS-stimulated human neutrophils in a concentration-dependent manner
   • Root extracts interact with TLR4 (Toll-like receptor 4) and LPS signaling pathways
   • The pterocarpan medicarpin inhibits 5-lipoxygenase and subsequently leukotriene formation
   • [Source: Kauhl et al. 2020, Front Pharmacol 11:889, PMID: 32595508]

4. Anti-adhesive Activity Against Uropathogenic E. coli

   • Aqueous root extract significantly inhibits adhesion of uropathogenic E. coli to T24 bladder epithelial cells in a concentration-dependent manner
   • The extract does not kill bacteria (no influence on E. coli proliferation at 125-1000 micrograms/mL) but prevents bacterial attachment to host cells
   • The mechanism does not involve FimH-mediated adhesion, suggesting a different anti-adhesive pathway than cranberry
   • This finding provides a mechanistic rationale for the traditional use in urinary tract infections
   • [Source: Deipenbrock et al. 2020, Planta Med 86(8):507-516, PMID: 31968378]

5. Potential Litholytic Effect

   • An in vitro study exposed seven surgically extracted human kidney stones to an O. spinosa solution
   • Statistically significant passage of calcium, phosphate, and uric acid was detected in the restharrow solution versus control
   • Uric acid stones showed higher dissolution rates than other stone types
   • This is the first in vitro evidence suggesting a direct litholytic effect, but translation to in vivo conditions is uncertain
   • [Source: Suveren et al. 2020, Arab J Urol 18(2):88-93]

Key Bioactive Compounds

Clinical Evidence Summary

The Core Problem: Near-Absence of Clinical Trials

Restharrow root represents one of the starkest examples of the gap between regulatory approval (Commission E, EMA) and modern clinical trial evidence. Despite centuries of documented traditional use and approval by major European regulatory bodies, no controlled clinical trials have been published evaluating the diuretic, aquaretic, or urinary tract irrigation effects of Ononis spinosa in human subjects. The EMA assessment report itself acknowledges that “laboratory studies demonstrated urine production increases” but “no patient studies conducted.”

This is an important transparency point: the Commission E and EMA approvals rest entirely on traditional use documentation, pharmacological plausibility, and the absence of reported harm — not on clinical efficacy data.

Preclinical Evidence

The preclinical evidence base is considerably stronger than the clinical base:

Evidence Limitations

• No randomized controlled trials in human subjects for any indication
• No dose-finding studies in humans
• No pharmacokinetic studies for restharrow-specific compounds
• The diuretic/aquaretic effect has been confirmed in animals but never formally measured in a human clinical trial
• The anti-inflammatory and anti-adhesive mechanisms have only been demonstrated in vitro
• The litholytic effect is based on a single in vitro study with surgically extracted stones
• The preclinical evidence from Muenster University (Hensel group) is emerging and methodologically sound, but remains preclinical

Honest Assessment

Restharrow root has a plausible pharmacological rationale and a centuries-long safety record, but its evidence base is essentially pre-modern by current EBM standards. The recent in vitro work from the University of Muenster (2018-2020) is beginning to build a molecular foundation, but clinical trials are needed to confirm relevance in human patients. Clinicians and patients should understand that using restharrow for irrigation therapy is based on traditional European practice, not on demonstrated clinical efficacy in controlled trials.

Safety Profile

Contraindications

• Edema due to impaired cardiac or renal function — because irrigation therapy requires high fluid intake (minimum 2 liters/day), which is contraindicated in fluid-restricted patients
• Conditions requiring reduced fluid intake (severe cardiac insufficiency, severe renal failure)
• Acute kidney disease
• Known hypersensitivity to Ononis spinosa or other Fabaceae plants
• Children under 12 years — insufficient safety data (EMA recommendation)

Drug Interactions

• None known — no drug interactions have been formally documented
• Theoretical caution with diuretics (potential additive effect), but this has not been observed or studied
• The absence of known interactions is partly due to the absence of pharmacokinetic studies, not proof of safety

Side Effects

• None known at recommended doses — no adverse effects have been reported in the traditional use documentation or in the EMA assessment
• The long history of use without reported adverse effects provides reasonable reassurance of safety at traditional doses
• The methanolic extract has been shown to have no cytotoxicity to primary human cells in vitro (PMID: 32344670)

Pregnancy and Lactation

• Not recommended due to lack of safety data
• No reproductive or developmental toxicity studies have been conducted
• No evidence of harm, but traditional precautionary avoidance applies
• The EMA explicitly states restharrow should not be used during pregnancy and lactation without medical advice

Toxicology

• No acute or chronic toxicity has been reported in the scientific literature
• Repeated-dose toxicity studies have been performed with ethanol extracts but studies with aqueous preparations (the traditional form of use) are lacking
• No carcinogenicity or mutagenicity data are available

Clinical Dosage

Herbal Tea (Primary Traditional Form)

Preparation of Restharrow Root Tea

The traditional preparation method is a decoction rather than a simple infusion, owing to the hard, woody nature of the root:

1. Place 2-3 g (approximately 1-2 teaspoons) of finely cut or coarsely powdered restharrow root in a cup
2. Pour 150 mL of boiling water over the root
3. Steep for 20-30 minutes (longer than typical herb teas due to the woody root)
4. Strain and drink between meals
5. Repeat 2-4 times daily
6. Critical: Maintain total fluid intake of at least 2 liters per day during treatment

Traditional Blasen- und Nierentee (Bladder and Kidney Tea) Formulas

Restharrow root is traditionally combined with other aquaretic herbs. A classic German pharmacy formula:

Example formula (Species diureticae type):

• Restharrow root (Ononidis radix) — 30%
• Birch leaf (Betulae folium) — 30%
• Goldenrod herb (Solidaginis herba) — 20%
• Horsetail herb (Equiseti herba) — 20%

Preparation: 1-2 tablespoons of the mixture per cup (150 mL boiling water), steep 15-20 minutes, 3-4 cups daily.

Key Commercial Products

• Aqualibra (Germany): Combination of restharrow root, Java tea, and goldenrod extracts — a registered herbal medicinal product for urinary tract complaints
• Bad Heilbrunner Nieren- und Blasentee (Germany): Traditional bladder and kidney tea containing restharrow among other herbs
• Various German pharmacy (Apotheke) restharrow root teas and combination diuretic teas

Duration of Treatment

• Consult a physician if symptoms persist beyond 1 week (EMA recommendation)
• Can be used for longer periods for prevention of kidney gravel, under medical supervision
• No specific maximum treatment duration established, but medical guidance is recommended for use beyond 2 weeks

Sources

• EMA Assessment Report on Ononis spinosa L., radix (EMA/HMPC/138316/2013)
• EMA Community Herbal Monograph on Ononis spinosa L., radix (EMA/HMPC/138319/2013)
• EMA Ononidis radix Product Page
• EMA Herbal Monograph on Species diureticae
• ESCOP Monograph — Ononidis radix (Restharrow Root)
• Arzneipflanzenlexikon — Spiny Restharrow
• Altmeyers Encyclopedia — Ononidis radix
• Addotey JNA et al. Isoflavonoids with inhibiting effects on human hyaluronidase-1 and norneolignan clitorienolactone B from Ononis spinosa L. root extract. Fitoterapia. 2018;130:169-174. PMID: 30176279
• Kauhl U et al. Root extracts from Ononis spinosa inhibit IL-8 release via interactions with TLR4 and LPS. Front Pharmacol. 2020;11:889. PMID: 32595508
• Deipenbrock M et al. Aqueous root extract from Ononis spinosa exerts anti-adhesive activity against uropathogenic Escherichia coli. Planta Med. 2020;86(8):507-516. PMID: 31968378
• Kramer C et al. Methanolic extract of the herb Ononis spinosa L. is an antifungal agent with no cytotoxicity to primary human cells. Pharmaceuticals. 2020;13(4):78. PMID: 32344670
• Gampe N et al. Characterization and identification of isoflavonoid glycosides in the root of Spiny restharrow by HPLC-QTOF-MS. J Pharm Biomed Anal. 2016;123:74-81. PMID: 26874257
• Suveren E et al. The possible litholytic effect of Ononis spinosa L. on various human kidney stones — an in vitro evaluation. Arab J Urol. 2020;18(2):88-93.
• Blumenthal M et al., eds. The Complete German Commission E Monographs: Therapeutic Guide to Herbal Medicines. Austin: American Botanical Council; 1998.

Connections

• See Goldenrod for the flagship European irrigation therapy herb (often combined with restharrow)
• See Birch Leaf for another classic Blasen- und Nierentee ingredient
• See Horsetail for a further aquaretic herb used in combination diuretic teas
• See Bearberry Uva Ursi for a urinary tract herb with a different mechanism (antiseptic via arbutin/hydroquinone rather than irrigation)
• See Cranberry for comparison of anti-adhesive mechanisms against uropathogenic E. coli (cranberry targets FimH; restharrow uses a different pathway)