Herb robert

Herb Robert (Geranium robertianum L.): A Comprehensive Reference

Identity, Taxonomy, and Botanical Description

Nomenclature and Classification

Geranium robertianum, commonly known as herb-robert or, in North America, as Robert's geranium, is a species of cranesbill that is widespread throughout the northern hemisphere and introduced to some countries in the southern. It belongs to the family Geraniaceae, a small botanical family of approximately 750 species grouped into 5–11 genera, generally comprising herbaceous plants covered by glandular simple leaves, usually deeply lobed, with flowers bearing five petals, five sepals, five to fifteen stamens, and five carpels. The most distinctive feature of this family is a beak-shaped fruit composed of five mericarps arranged around an inner central column.

The genus name Geranium comes from the Greek noun geranos, meaning "crane," a reference to the beak-like fruit (seed capsule) reminiscent of the long beak of a crane. The specific epithet robertianum and the most frequent English common name "Herb-Robert" are both derived from the medieval Latin name herba Roberti, or herba Sancti Ruperti. The English form, as "Herbe Robert," was already in use by the 13th century. The origin of the name and the connection with the Austrian saint may both lie in the distinctive redness of the typical plant, which could be a corruption or modification of herba rubra, this in turn leading through the colour to an association with blood, and with the eighth-century St Rupert or Rudbert of Salzburg, who was invoked to heal bleeding wounds, ulcers, and erysipelas.

Common Names

G. robertianum L. is commonly known as herb Robert or red robin. Other common names include dragon's blood, stork's bill, and wild crane's bill. The plant is also colloquially called "Stinky Bob" due to its distinctive scent.

Morphology and Habitat

Herb-robert is a small, usually biennial but sometimes annual or even short-lived perennial herb that typically grows to about 30 cm (1 ft) tall and broad, or sometimes up to about twice that size. It produces usually pink but occasionally white five-petalled flowers typically 1 to 1.5 cm across. The three- or five-lobed hairy stalked leaves are deeply dissected; when crushed they give off a somewhat spicy and unpleasant odour. The branching stems are also hairy and, like the leaves, gradually turn red, generally beginning with those nearest to the base.

Geranium robertianum is very common throughout Britain and Ireland, and is found in many mainland European countries. Its natural range extends down to northern Africa and across into western Asia. Elsewhere in the temperate zone, including the Americas, Herb Robert is an introduced but now naturalised species, and in some places this plant is considered to be a noxious invasive weed. It grows at altitudes from sea level to 700 m at Great Dun Fell in England and up to 2,400 m in Kashmir.

Plant Parts Used and Preparation Forms

The aerial parts of the plant — leaves, stems, and flowers — are the parts most commonly collected and used in herbal practice. These therapeutic properties make it effective when administered internally in various pharmaceutical forms or extracts, in the management of multiple pathologies. Traditional preparations include infusions (teas), decoctions, tinctures, and topical poultices. A hot water infusion, once cooled, can be used as a mouthwash for gum disease or sore throats as well as for skin conditions where astringency is called for. Scientific studies have predominantly employed solid-liquid extracts using solvents including water, methanol, ethanol, ethyl acetate, and hexane to characterize phytochemical and biological properties.

Traditional and Historical Use

European Folk Medicine

Geranium robertianum L. has long been used in the folk medicine of several countries and in the practice of herbalism for a number of different therapeutic purposes. There are accounts of it being used in the folk medicine of several countries, including as a treatment for diarrhea, to improve functioning of the liver and gallbladder, for toothache and nosebleeds, and as a vulnerary (used for or useful in healing wounds).

The inhabitants of the high mountainous regions of Montenegro have indicated the above-ground parts of G. robertianum as applicable to diarrhea, stomach inflammation, diseases of the gallbladder, kidneys, bladder, and ureters and externally to hard-to-heal wounds and mild rashes. G. robertianum has been used for the treatment of haemorrhage, diarrhoea, mouthwash, wounds, gall stones, and burns.

In the British Isles and broader European tradition, the plant's pronounced astringent properties — arising from its high tannin content — made it a go-to remedy for both external and internal applications. Its high concentration of tannins provided powerful astringent qualities, making it a primary ingredient for traditional wound healing. These properties were utilized externally to staunch minor bleeding, reduce swelling, and help shrink inflamed tissues. Internally, the herb was sought for detoxification and supporting the digestive tract. With its high tannin content, herb robert is particularly indicated where astringency is required. It is used for the gastrointestinal system, for peptic ulcers, gastric ulcers, or diarrhoea. In the reproductive system, it can be used for metrorrhagia and menorrhagia.

There is also a tradition of using the plant as a topical insect repellent. Freshly picked leaves, when rubbed on the body, are said to repel mosquitoes.

Broader Traditional Medical Systems

Since ancient times, species of Geranium have been utilized in numerous conventional health systems across the globe, such as Indian Ayurveda, Traditional Chinese medicine, and various indigenous medical practices, by means of herbal formulations. G. robertianum has specifically been used for the treatment of haemorrhage, diarrhoea, mouthwash, wounds, gall stones, and burns across various cultural traditions.

These therapeutic properties make it effective when administered internally in various forms and preparations in the management of multiple pathologies such as diarrhea, gastritis, ulcers, flu, sinusitis, diabetes, hypertension, hypercholesterolaemia, cancer, rheumatism, genitourinary problems, haemorrhages, and liver disorders. In Deliblato Sands, Serbia, this plant is known and used for its antidiarrheal and antihemorrhagic properties.

The plant's traditional role in wound care is particularly well-documented across European ethnobotanical literature. The association with St. Rupert of Salzburg — specifically invoked to heal bleeding wounds, ulcers, and erysipelas — reflects how deeply embedded the plant was in medieval European medical culture, with the name itself encoding its therapeutic reputation.

Key Constituents and Active Compounds

Phenolic Compounds: The Dominant Chemical Class

The chemistry of the Geranium genus is reasonably well-known and clearly dominated by phenolic constituents, with the most studied classes of compounds being tannins, flavonoids, and phenolic acids. The phytochemical characterization of G. robertianum has been focused mostly on the investigation of solid-liquid extracts of the plant, with special emphasis on phenolic compounds, particularly flavonoids.

Hydrolysable Tannins — Including Geraniin

Ellagitannins are the most frequently isolated tannins in G. robertianum, the main one being geraniin. In addition, the presence of proanthocyanidins has been reported. The ellagitannin geraniin, which received its name after crystallizing from Geranium thunbergii, is the Geranium genus's most unique single compound. This secondary metabolite is found in all types of leaves in Geranium species. Since HPLC has found geraniin in each of the 15 species examined, it would appear that geraniin is the distinctive hydrolysable tannin of the genus.

The aerial parts of G. robertianum contain tannins including geraniin, isogeraniin, and β-penta-O-galloylglucose, as well as bitter substances, traces of essential oil, citric acid, resins, alkaloids, saponins, and oxalate.

Phenolic Acids

Phenolic acids in G. robertianum are represented chiefly by gallic, ellagic, ferulic, caffeic, and chlorogenic acids. Among the phenolic compounds, several additional constituents have been identified: gallic, caffeic, ferulic, p-coumaric, syringic, and ellagic acids, as well as the flavonoids rutin, luteolin, quercetin, isoquercitrin, quercitrin, hyperoside, kaempferol, and astragalin.

Flavonoids

Flavonoids are abundant in this plant, including quercetin and kaempferol, present as aglycones or in glycosidic combinations. Phytochemical investigations of G. robertianum extracts indicate a predominance of hydrolyzable tannins, along with a diverse profile of phenolic acids (ferulic, coumaric, chlorogenic, caffeic, gallic, and ellagic acids), and flavonoids (notably quercetin and kaempferol, present either as glycosides or in aglycone form).

Non-Phenolic Compounds

Non-phenolic compounds have also been described in G. robertianum, including lectins, saponins, and alkaloids. In smaller amounts, the extracts also contain lectins, alkaloids, saponins, and organic acids, including malic and citric acids. When G. robertianum was analyzed, tartaric acid was found to be absent, while citric and malic acids were present.

Essential Oil Constituents

The main constituents of the essential oil isolated from the aerial parts are represented by linalool, γ-terpinene, germacrene-D, limonene, geraniol, α-terpineol, and phytol. Studies concerning the essential oils of this species are still scarce, but the number of identified compounds is high.

Vitamins and Micronutrients

Several vitamins — A, B₁, B₂, B₃, C, and E — have been identified and quantified in leaves. In one study, phytochemical analysis and vitamin content determination were carried out using standard analytical methods to determine their various levels. Iron (Fe) was found to be the most abundant element in one analyzed extract. Fe was found to be the most abundant element, followed by Zn, Mn, Ni, and Cr. Four potentially hazardous heavy metals — As, Co, Pb, and Cd — were found to be under the detection limit.

Established and Proposed Mechanisms of Action

Antioxidant Activity

Compounds such as quercetin, kaempferol, geraniin, and proanthocyanidins are associated with strong antioxidant properties, promoting free radical scavenging and cellular protection. Both leaf and stem extracts reveal high amounts of ellagitannins, with a slight prevalence of these compounds observed in the extract from leaves. High radical scavenging activities against DPPH˙, ABTS˙⁺ and OH˙ were observed for both leaf and stem extracts, as well as good activities toward ferric reducing antioxidant power, lipid peroxidation, and oxygen radical absorbance capacity.

Antimicrobial Activity

Essential oils and extracts from G. robertianum exhibit significant antimicrobial activity against Gram-positive and Gram-negative bacteria and various fungi, including resistant strains. These effects are linked to secondary metabolites that disrupt membranes, inhibit microbial enzymes, and modulate oxidative stress.

Astringent and Hemostatic Mechanisms

The high tannin content — principally geraniin and related ellagitannins — is the primary mechanistic basis for the plant's well-recognised astringent effects. Tannins are strongly associated with astringency. They can help create a tightening, drying sensation on tissues, which helps explain why astringent plants are often used for inflamed gums, minor weeping skin lesions, or loose stools.

Anti-inflammatory Mechanisms

Geranium extracts have been shown to significantly reduce the expression of the proinflammatory cytokine TNF-α and inflammatory and oxidative stress genes (NF-κB, HO-1, Nrf-2) while increasing Keap-1 in gastric mucosa, presenting a significant protective effect against mucosal injury.

Anticancer Mechanisms (Preclinical)

On A253 human salivary gland carcinoma cells, a G. robertianum extract elicited a dose-dependent antiproliferative effect, produced morphological changes, and increased reactive oxygen species (ROS) and both caspase-3/7 and caspase-9 levels — suggesting the induction of apoptotic cell death pathways.

Scientific Evidence by Area of Use

Antioxidant Activity

Evidence type: In vitro laboratory studies.

In one study, the phenolic profile of leaves and stems decoctions of Geranium robertianum L. was elucidated through UHPLC-DAD-ESI-MSⁿ analysis, and their antioxidant and anti-inflammatory potential were assessed in vitro. Importantly, and envisaging the use of these extracts in human diets, the potential toxicity of bioactive concentrations was also addressed in macrophages and hepatocytes. In a 2026 study, the antioxidant activity of a G. robertianum ethanolic extract was determined by means of three different colorimetric assays (DPPH, ABTS, and FRAP), with results indicating that the ABTS assay showed the highest antioxidant capacity.

Evidence strength: Multiple consistent in vitro studies confirm robust antioxidant activity. No human clinical trials exist. All findings are preliminary and cannot be extrapolated directly to clinical benefit.

Anti-inflammatory Activity

Evidence type: In vitro and animal studies.

The confirmation of the antioxidant, antimicrobial, anti-inflammatory, anti-hyperglycaemic, and cytotoxic activities of G. robertianum, closely related to its high content of phenolic compounds, has come to corroborate to some extent the recognised beneficial properties of this medicinal plant. Researchers concluded that Geranium robertianum and aloe vera offer potent gastroprotective effects in aspirin-induced ulcers via antioxidant, anti-inflammatory, anxiolytic, and mucosal-preserving mechanisms, highlighting their therapeutic potential for gastric ulcer prevention or treatment.

Evidence strength: Preliminary; based on in vitro and animal models. No human trials have evaluated the anti-inflammatory effects of Herb Robert directly.

Antimicrobial Activity (Antibacterial, Antifungal, Antiviral)

Evidence type: In vitro laboratory studies (2023, Pharmaceutics).

The purpose of a 2023 study was to assess the phytochemical profile of extracts from aerial parts of G. robertianum, commercially available in Poland, and to study their anticancer potential and antimicrobial properties, including antiviral, antibacterial, and antifungal effects. Additionally, the bioactivity of fractions obtained from the hexane and ethyl acetate extract was analyzed.

The highest antibacterial activity was observed for fraction GrEA4 against Gram-positive bacteria, including Micrococcus luteus ATCC 10240 (MIC 8 μg/mL), Staphylococcus epidermidis ATCC 12228 (MIC 16 μg/mL), Staphylococcus aureus ATCC 43300 (MIC 125 μg/mL), Enterococcus faecalis ATCC 29212 (MIC 125 μg/mL), and Bacillus subtilis ATCC 6633 (MIC 125 μg/mL). The observed antibacterial effect may justify the traditional use of G. robertianum to treat hard-to-heal wounds.

Regarding antiviral effects, the hexane and ethyl acetate extracts inhibited the development of HHV-1-induced cytopathic effect (CPE) in virus-infected cells and decreased the viral load by 0.52 log and 1.42 log, respectively. Among the analyzed fractions, only those obtained from the ethyl acetate extract showed the ability to decrease the CPE and reduce the viral load.

One ethanolic extract exhibited moderate antibacterial activity against both Gram-positive and Gram-negative bacteria, with inhibition zones generally comparable to those of levofloxacin. However, the extract was significantly less effective against the P. aeruginosa strain.

Evidence strength: Preliminary; all findings are from in vitro cell culture experiments. No clinical trials in humans. Activity against P. aeruginosa (a common Gram-negative pathogen) was notably limited.

Anticancer Activity

Evidence type: In vitro cell-line studies.

The cytotoxic influence on cancer cells, including MCF-7 (breast adenocarcinoma), NCI-H460 (non-small cell lung cancer), HeLa (cervical carcinoma), and HepG2 (hepatocellular carcinoma), has been described in prior studies.

In the 2023 Pharmaceutics study, significant anticancer activity was found for G. robertianum hexane extract (GrH) and ethyl acetate extract (GrEA), with a selectivity index (SI) between 2.02 and 4.39 — meaning the extracts showed preferential toxicity toward cancer cells over normal cells.

A 2026 study published in Antioxidants (MDPI) examined activity on a salivary gland carcinoma cell line. An ethanolic extract obtained from the aerial parts of G. robertianum L. (GR) was investigated in terms of phytochemical composition and biological activity. GR extract exhibited high levels of phenolic compounds and flavonoids, and its antioxidant activity was determined by DPPH, ABTS, and FRAP assays. On A253 human salivary gland carcinoma cells, the GR extract elicited a dose-dependent antiproliferative effect, produced morphological changes, and increased ROS and both caspase-3/7 and caspase-9 levels.

Both traditional use and the literature data point to the anticancer potential of G. robertianum, but this activity had not been previously assessed regarding head and neck cancers (HNCs) or colon cancer before the 2023 study.

Evidence strength: Weak-to-preliminary; entirely in vitro at this stage. Cell-line selectivity indices are promising, but results in cell culture models do not reliably predict clinical efficacy or safety in humans. No animal or human trials on cancer outcomes have been reported.

Antidiabetic and Metabolic Effects

Evidence type: Animal model study (2010).

In a study of Geranium robertianum L. (herb Robert) leaf decoctions in Goto-Kakizaki (GK) rats (a model of type 2 diabetes), oral administration of G. robertianum leaf decoctions over a period of four weeks lowered the plasma glucose levels in diabetic rats. Furthermore, the treatment improved liver mitochondrial respiratory parameters (state 3, state 4 and FCCP-stimulated respiration) and increased oxidative phosphorylation efficiency. This study was published in Acta Biochimica Polonica (2010) and nicknamed "MitoTea" by the authors.

Herb Robert may be considered within the treatment of type 2 diabetes due to its effect on lowering blood glucose levels and supporting mitochondrial function.

Evidence strength: Preliminary; based solely on a single animal study using a non-obese diabetic rat model. No human clinical data exist. Extrapolation to human antidiabetic use is not warranted from this evidence alone.

Neuroprotective Effects

Evidence type: In vitro cell model study (2023).

For the first time, a 2023 study investigated the in vitro neuroprotective effects of leaf extract of G. robertianum over a wide dose range (0–200 µg/mL) on the Parkinson's disease model using retinoic acid (RA)-differentiated SH-SY5Y cells and 1-methyl-4-phenylpyridinium (MPP⁺)-induced neurotoxicity. The neuroprotective effects were determined by MTT and lactate dehydrogenase (LDH) release assays. Results showed that G. robertianum leaf extract ameliorated cytotoxicity and oxidative damage by MPP⁺. Moreover, the extract exhibited a protective activity against MPP⁺-induced apoptosis. The findings suggest a promising new candidate for Parkinson's disease through neuroprotective mechanisms with respect to antioxidant and apoptosis-inhibitory properties of the water extracts.

Evidence strength: Very preliminary; a single in vitro cell model study only. No animal or human data. The neuroprotective potential of Herb Robert against Parkinson's disease has not been demonstrated beyond this cell model.

Gastroprotective and Digestive Effects

Evidence type: In vitro and animal studies; traditional use corroboration.

Herb Robert's anti-inflammatory, astringent, and antimicrobial effects are of benefit to the treatment of ulceration, inflammation, or problems associated with diarrhoea in the gastrointestinal tract, and may explain its longstanding traditional use for these types of conditions. Pre-treatment with aloe vera gel and geranium showed significant antioxidant activities with free radical scavenging and ferric-reducing power. They improved the stomach architecture and alleviated anxiety-like behaviour and motor deficits. They significantly reduced the expression of proinflammatory cytokine TNF-α and inflammatory and oxidative stress genes (NF-κB, HO-1, Nrf-2) while increasing Keap-1 in gastric mucosa. Data presented a significant protective effect against aspirin-induced gastric ulceration.

Evidence strength: Preliminary; corroborated by traditional use and in vitro or animal evidence. No human clinical trials on digestive or gastroprotective outcomes have been published.

Body Systems and Health Areas Associated with Herb Robert

• Gastrointestinal system: Used in folk and herbal medicine in many countries to treat digestive system disorders, specifically diarrhoea, stomach inflammation, peptic ulcers, and gastric ulcers.
• Hepatobiliary system: Traditional use for diseases of the gallbladder and improvement of liver function, supported by the 2010 animal study demonstrating improved liver mitochondrial respiratory parameters.
• Urogenital system: Traditional use for diseases of the kidneys, bladder, and ureters. In the reproductive system, it can be used for metrorrhagia and menorrhagia.
• Integumentary system (skin and wound healing): Externally applicable to hard-to-heal wounds and mild rashes. The high tannin content is considered the primary basis for hemostatic and wound-healing properties.
• Oral cavity: A hot water infusion, once cooled, can be used as a mouthwash for gum disease or sore throats.
• Metabolic/endocrine system: Animal model evidence for antihyperglycaemic and mitochondrial benefits in type 2 diabetes.
• Nervous system: Preliminary in vitro evidence for neuroprotective activity in a Parkinson's disease cellular model.
• Oncology (preclinical only): Selective cytotoxicity demonstrated in vitro against pharyngeal, colon, breast, lung, cervical, hepatic, and salivary gland cancer cell lines.

Dosage Forms and Reported Dosages

No standardized, clinically validated dosage for Herb Robert has been established in any regulatory monograph or clinical trial. The following dosage-related information reflects what has been reported in the scientific literature:

• Animal study (antidiabetic): Researchers evaluated the effects of Geranium robertianum leaf decoctions over a four-week period, during which diabetic rats received daily oral doses of the decoction. Specific dose values in mg/kg were not detailed in the available abstract data.
• In vitro (neuroprotective): The in vitro neuroprotective study tested leaf extract over a wide dose range of 0–200 µg/mL.
• In vitro (anticancer): Selectivity indices between 2.02 and 4.39 were recorded for hexane and ethyl acetate extracts at unspecified concentrations in the 2023 Pharmaceutics study.
• In vitro (antibacterial, 2026): Minimum inhibitory concentrations (MICs) against Gram-positive bacteria ranged from 8 μg/mL (against M. luteus) to 125 μg/mL (against S. aureus, E. faecalis, and B. subtilis).

Traditional preparations (infusions, decoctions, tinctures) are used without a formally established dose in any pharmacopoeia or regulatory monograph for this species. Even though G. robertianum L. has been reported to be commonly used in traditional folk medicine to treat various diseases, the actual biological activity is surprisingly understudied.

Safety Considerations

General Safety Profile

Studies have confirmed antibacterial activity (against a very limited panel of bacteria), as well as the antioxidant, anti-inflammatory, and antihyperglycaemic activities of G. robertianum, but formal systematic toxicological evaluation in humans is lacking. Geranium robertianum L. is a widely distributed plant used as traditional herbal medicine, but the knowledge of its biological properties still needs to be improved.

Tannin Load and Oxalate Content

The high hydrolysable tannin content that underlies many of the plant's proposed benefits also carries potential safety implications at high doses. Tannins in large amounts can impair iron and protein absorption and may irritate gastric mucosa. Additionally, the aerial parts contain oxalate, which in large quantities may be relevant for individuals with a history of calcium oxalate kidney stones or oxalate-related metabolic disorders.

In Vitro Toxicity Assessment

Envisaging the use of extracts in human diets, one study specifically addressed the potential toxicity of bioactive concentrations in macrophages and hepatocytes — representing a relevant precautionary research step, though results from cell-based toxicity models are not directly predictive of in vivo human toxicity.

Regulatory Status

As of the current date, Geranium robertianum is not the subject of an approved monograph by the European Medicines Agency (EMA), the German Commission E, ESCOP, or the WHO for medicinal use. It does not appear in any major regulatory pharmacopoeial listing as an approved therapeutic agent. The medicinal value of herb-robert is considered uncertain by general botanical references, reflecting the gap between its extensive traditional use and the limited clinical evidence base.

Evidence Gaps

Even though G. robertianum L. has been reported to be commonly used in traditional folk medicine to treat various diseases, the actual biological activity is surprisingly understudied. The totality of scientific evidence consists of in vitro cell studies and a small number of animal experiments. No randomized controlled trials or systematic clinical studies in humans have been published for any indication. All biological activity data must therefore be characterized as exploratory or hypothesis-generating rather than clinically proven.

Overall Evidence Summary

The chemistry of G. robertianum is clearly dominated by phenolic constituents, the most studied classes being tannins, flavonoids, and phenolic acids. The confirmation of antioxidant, antimicrobial, anti-inflammatory, anti-hyperglycaemic, and cytotoxic activities of G. robertianum, closely related to its high content of phenolic compounds, has come to corroborate to some extent the recognised beneficial properties of this medicinal plant. Nonetheless, the body of published evidence remains at the in vitro and animal-model level. The gap between these preliminary findings and clinical validation is substantial, and no human studies have been published to support specific therapeutic claims. The plant's long history of use across European and global folk medicine traditions provides ethnobotanical context and a basis for ongoing investigation, but does not substitute for rigorous clinical evidence.

References

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• Graça VC et al. "Antioxidant and anti-inflammatory activities of Geranium robertianum L. decoctions." PubMed, 2017.
• Ferreira FM et al. "'MitoTea': Geranium robertianum L. decoctions decrease blood glucose levels and improve liver mitochondrial oxidative phosphorylation in diabetic Goto-Kakizaki rats." Acta Biochimica Polonica, 2010. PubMed.
• Arslan ME, Yilmaz A. "Neuroprotective effects of Geranium robertianum L. aqueous extract on the cellular Parkinson's disease model." European Review for Medical and Pharmacological Sciences, 2023.
• Haj Ali D et al. "Phytochemical Characterization and Biological Assessment of Geranium robertianum L. Ethanolic Extract on Human Salivary Gland Carcinoma Cells." Antioxidants 2026, 15(3):296. MDPI.
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