Hempnettle

Hempnettle (Galeopsis spp.): A Comprehensive Reference

1. Identity: Botanical Names, Taxonomy, and Natural Source

1.1 Genus and Accepted Species

Galeopsis is a genus of annual herbaceous plants native to Europe and Asia; members of this genus often have common names ending in "hemp-nettle" or "hempnettle." Some species are naturalized in North America and New Zealand. The plants are considered poisonous, and while several species are widespread weeds, some are used as medicinal herbs.

The genus belongs to the family Lamiaceae (the mint or deadnettle family). Hempnettles belong to the Lamiaceae family, which is more commonly associated with aromatic plants such as mint and basil. The genus name "Galeopsis" is an ancient Greek name derived from "galē," meaning "weasel," and "opsis," meaning "appearance," thus translating as "weasel-resembling."

The principal species of pharmacognostic and dietary supplement interest include:

• Galeopsis segetum Necker (syn. Galeopsis ochroleuca Lamarck) — downy hemp-nettle. The official herbal drug entry "Galeopsidis herba" refers to this species, which has yellow flowers, and it is noted for its iridoid monoterpenes including harpagide, 8-O-acetylharpagide, antirrinoside, and 5-O-glucosylantirrinoside. This is the species most widely recognized in European phytotherapy references.
• Galeopsis tetrahit L. — common hemp-nettle or brittlestem hemp-nettle. Synonyms include Galeopsis lactiflora, Galeopsis neglecta, Galeopsis silvestris, Galeopsis urticifolia, Ladanum tetrahit, and Lamium tetrahit. Although G. tetrahit is ethnopharmacologically significant, it remains relatively under-investigated compared with other phenolic-rich Lamiaceae genera; however, recent studies have highlighted its promising phytochemical profile, especially in the leaves, which tend to accumulate higher phenolic levels than stems or roots.
• Galeopsis bifida Boenn. — bifid hemp-nettle. G. bifida is a synanthropic species widely distributed across Europe, Asia, and Siberia, deeply embedded in the ethnomedical tradition of Asian healers.
• Galeopsis speciosa Mill. — large-flowered hemp-nettle, with similar chemical profile trends to the other species.
• Galeopsis ladanum L. — red hemp-nettle, which appears in older European pharmacopeias and modern laboratory screens.
• Galeopsis pubescens Besser — hairy or downy hemp-nettle. In the past, this hempnettle was used in traditional medicine; it is widely distributed across Europe, spanning from the eastern parts of France to Russia, the Caucasus, and Siberia.

1.2 Morphology and Habitat

The common hemp-nettle is a biennial or annual herb that can reach heights of 30 to 80 cm. Key identifying traits include broadly ovate leaves with serrated margins, and square-shaped stems — a hallmark of plants in the Lamiaceae family. The plant is recognizable thanks to its opposite, serrated leaves and slender stems bearing clusters of tubular flowers, which are typically pale purple or lilac, blooming in whorls, and characterized by their two-lipped structure, making them particularly attractive to pollinators. The nettle-like leaves have regular large teeth around their margins, and flowers are usually pinkish-purple but can be almost white; yellow-flowered specimens also occur.

In its native Eurasian range, G. tetrahit is considered native in Europe and temperate regions of Asia, and it has been found as a naturalized introduction mainly in the northern continental United States, Alaska, and Canada. It thrives in diverse habitats, including forest margins, ruderal areas, agricultural edges, and disturbed soils, reflecting its notable ecological adaptability.

1.3 Taxonomic Note on G. tetrahit Origins

The distinctly broad habitat range of common hemp-nettle may reflect its polyploid origin: it is an amphidiploid formed by a complicated cross between two diploids, G. pubescens and G. speciosa, to produce a new tetraploid species. The same two parent species also crossed to give rise to the rather similar G. bifida.

1.4 Common Preparations and Forms

The official drug material, "Galeopsidis herba," consists of the aboveground parts of Galeopsis segetum gathered during the flowering season, prepared as ground and cut herb for teas and other galenical preparations for internal use. The above-ground herb is dried and used mostly as a tea; a juice or extract can also be made from fresh or dried plant. Hemp-nettle has no significance as a culinary herb; it has a faint smell and tastes slightly salty, bitter, and a bit slimy.

The named common preparations include:

• Herbal infusion/tea — the predominant traditional form, prepared from dried aerial parts
• Decoction — the flowering plant, being astringent, diuretic, and mildly expectorant, has been prepared as a decoction for the treatment of whooping cough, bronchitis, tracheitis, and similar conditions.
• Fresh or dried extract / tincture — used in both European folk herbalism and in the ethnomedical tradition of Siberian/Far Eastern healers
• Homeopathic remedy — a homeopathic remedy is made from the plant and is used to treat disorders of the spleen.

---

2. Traditional and Historical Use

2.1 European Folk Medicine

Traditional European herbal medicine documents the long-standing use of Galeopsis spp. for inflammatory and respiratory conditions, wound healing, and general tonic preparations. The plant was used as far back as antiquity to treat respiratory illnesses; later it was also used for its diuretic and wound-cleansing effects. In the 18th and 19th centuries, it was an ingredient in "miracle cures" for tuberculosis.

In the 18th and 19th centuries, it was an ingredient in preparations sold on the market as "Blankenheimer Tea" or "Lieber'scher Emaciation Tea" at high prices, but these proved to be ineffective and were eventually banned; the herb subsequently fell into obscurity. Today it is used to treat minor respiratory illnesses.

Herbalists used hempnettle to soothe respiratory ailments; infusions and teas made from its aerial parts were commonly prescribed for coughs, bronchitis, and hoarseness, with its mild expectorant quality helping to ease chest congestion and support clearer breathing.

2.2 Documented Traditional Indications

Galeopsis spp. have been used in traditional practice mainly for their sedative, neuroprotective, antioxidant, anti-inflammatory, expectorant, astringent, and diuretic properties. The primary historical therapeutic areas included:

• Respiratory conditions: coughs, bronchitis, tracheitis, whooping cough, asthma, and pulmonary complaints generally
• Wound healing and skin ailments: wound-cleansing and tissue-wasting complaints
• Diuretic use: fluid retention and related conditions
• Digestive complaints: G. bifida preparations are utilized in the form of a decoction to treat oral afflictions (stomatitis) and gastrointestinal disorders, including gastritis, ulcers, gastroenteritis, and inflammations affecting the esophagus, stomach, or intestines, as well as conjunctivitis and cystitis.

2.3 Asian and Siberian Ethnomedical Traditions

In the Far East, a tincture derived from the aerial parts of G. bifida is employed to stimulate the appetite, manage gastric ailments, and address epilepsy, while nomadic populations in northern Asia use the plant for the treatment of hepatic diseases.

2.4 North American Ethnobotany

Although brittlestem hemp-nettle is not native to North America, it has been present long enough that the Iroquois incorporated it into herbal medicine, using an infusion of the roots to induce vomiting as an emetic and as a cure for bewitching.

---

3. Key Constituents and Established Chemical Profile

3.1 Overview of Compound Classes

In the chemical composition of Galeopsis spp., flavonoids, phenolic acids, phenylpropanoid glycosides, iridoids, diterpenoids, triterpenoid compounds, essential oils, and fatty acids have been identified.

3.2 Iridoid Glycosides

Iridoids are among the most pharmacognostically important constituents. The specific iridoid monoterpenes identified in Galeopsis segetum include harpagide, 8-O-acetylharpagide, antirrinoside, and 5-O-glucosylantirrinoside.

In G. bifida, six iridoid glycosides were identified against reference standards: harpagide, harpagide 8-O-acetate, ajugol, secologanin, reptoside, and ajugoside. Harpagide and harpagide 8-O-acetate are common components of Galeopsis species and the broader Lamiaceae family. Harpagide derivatives predominated among iridoids, accounting for 15 of the 33 total iridoid compounds detected.

All species of Galeopsis contain aucubin-like glycosides in roots, leaves, and seeds. Acetylharpagide is typical of leaves of species of the subgenus Ladanum, and galiridoside characterizes leaves of taxa of the subgenus Tetrahit; however, the leaves of Galeopsis pubescens, G. segetum, and G. pyrenaica contain appreciable amounts of both constituents.

The particularly valued active iridoid in downy hemp-nettle is harpagide. These bitter substances have antimicrobial and anti-inflammatory effects and harpagide is thought to be a degradation product of harpagoside — the compound responsible for devil's claw's effectiveness in treating painful degenerative joint diseases — showing similar effects.

3.3 Phenylethanoid (Phenylpropanoid) Glycosides

Galeopsis tetrahit L. (Lamiaceae) is a traditional European medicinal species rich in phenolic compounds, among which verbascoside is a key bioactive marker with strong antioxidant potential. Analysis of dry extract from G. tetrahit leaves yielded 345.8 ± 28.3 mg verbascoside per gram of dry extract (34.6%, w/w), corresponding to approximately 59.8 mg/g in dried leaves. Verbascoside is widely distributed within Lamiaceae and Plantaginaceae and is frequently used as a quantitative chemical marker in the standardization of herbal extracts due to its strong bioactivity and well-characterized pharmacological relevance.

Additional phenylethanoid glycosides identified include isoverbascoside. Earlier research identified several bioactive metabolites with acetylcholinesterase (AChE) inhibitory properties, including iridoid glycosides (harpagide, harpagide 8-O-acetate, ajugoside), phenylethanoid glycosides (verbascoside, isoverbascoside), flavonoid glycosides (luteolin and apigenin derivatives), and hydroxycinnamic acids (caffeoylquinic acids, e.g., chlorogenic acid).

3.4 Phenolic Acids and Flavonoids

Studies confirm that leaves contain the highest concentrations of phenolic acids and flavonoids, particularly chlorogenic acid, p-coumaric acid, and ferulic acid, which were identified as major bioactive compounds. Chlorogenic acid was the most abundant compound in an investigation of three wild-grown Romanian species, with the highest levels detected in G. tetrahit leaves at 22,347.907 ± 1,117.395 μg/g, followed by G. tetrahit aerial parts at 11,678.509 ± 583.925 μg/g and G. speciosa leaves at 8,712.628 ± 435.631 μg/g.

Flavonoids identified across the genus include luteolin glycosides and apigenin glycosides. High content of antioxidant and anti-inflammatory compounds including verbascoside, 3-O-caffeoylquinic acid, luteolin, and apigenin glycosides has been documented in G. bifida.

3.5 Silicic Acid and Tannins

The phytochemical profile also includes silicic acid (to some extent water-soluble) and tannins. The silicic acid in downy hemp-nettle is considered to strengthen connective tissue and to support hair and horn growth as well as cartilage tissue.

3.6 Organ-Specific Distribution

An unequal quantitative distribution of metabolites is observed within separate organs of the plant, characterized by high accumulation of most compounds within the aerial part (leaves and flowers). In G. bifida, two chemotypes based on geographical origin were identified: the southern Siberian type accumulates flavone glucuronides, while the northern type tends to accumulate high levels of phenylpropanoids and acylated flavone glucosides.

A major challenge in phytochemical comparison across studies is the strong influence of plant origin, environmental stressors, and harvest conditions on secondary metabolite accumulation; phenolic compounds including phenylethanoid glycosides are known to vary significantly with altitude, sunlight exposure, soil composition, and developmental stage.

---

4. Mechanisms of Action

4.1 Expectorant Activity

"The herb acts as an expectorant, due to its saponin content, and as an astringent because of the tannins, silicic acid, iridoids and antirrhinoside," as summarized in pharmacognostic references. Hempnettle helps loosen congestion in the chest and airways so it can be coughed up, and can also dry out the tissues, which may reduce swelling.

4.2 Antioxidant Mechanisms

Flavonoid-rich extracts exhibit stronger antioxidant activity, requiring lower concentrations to achieve 50% inhibition in radical scavenging assays. The strong positive correlation between total flavonoid content and FRAP (ferric reducing antioxidant power) further supports the role of flavonoids as efficient electron donors, reinforcing their involvement in redox reactions.

Antioxidant assays (DPPH, ABTS, FRAP), total phenolic content, and total flavonoid content confirmed notable radical scavenging and reducing activity in G. tetrahit extracts, with pure verbascoside showing markedly stronger effects, supporting its major contribution to the extract's antioxidant potential.

4.3 Acetylcholinesterase (AChE) Inhibition

Romanian population studies demonstrated that G. tetrahit leaf extracts exhibit strong antioxidant properties including potent DPPH radical scavenging and acetylcholinesterase inhibitory activity. AChE inhibition activity increases progressively from roots to aerial parts to leaves, with leaves consistently exhibiting the strongest inhibitory effects across all Galeopsis spp.; G. tetrahit leaves had the strongest inhibition with an IC₅₀ of 4.002 ± 0.32 mg/mL, followed by G. speciosa leaves (6.92 ± 0.14 mg/mL) and G. bifida leaves (6.97 ± 0.68 mg/mL).

4.4 Anti-Inflammatory Mechanisms via Iridoids and Verbascoside

A variety of iridoids have been reported to possess significant anti-inflammatory activities. Several in vitro studies have shown that hydrolyzed products of various iridoids showed better activity; the hydrolysis of the glycosidic bonds by β-glucosidase — for example in harpagide and harpagoside — is considered a prerequisite for activity.

The biological activities of verbascoside and isoverbascoside, including their antimicrobial, neuroprotective, immunomodulatory, anti-inflammatory, antioxidative, and free radical-scavenging activities, are being extensively studied in vitro and in vivo and clinically. In cell-based models, verbascoside increased the activity of the antioxidant enzyme SOD and reduced the oxidative stress indicator 8-OHdG, as well as apoptosis; it also upregulated PGC1-α and NRF1 expression and promoted mitochondrial biogenesis, mediated by suppression of PKC/HMGB1/RAGE/NFκB signaling.

---

5. Scientific Evidence by Area of Use

5.1 Respiratory Health

Traditional basis: People have historically taken hempnettle tea for mild swelling of the airways, cough, bronchitis, and fluid retention.

Evidence strength: People use hempnettle tea for respiratory tract infections and other purposes, but there is no good scientific evidence to support any use. No controlled human clinical trials investigating hempnettle specifically for respiratory outcomes have been identified in the peer-reviewed literature. The expectorant and astringent mechanisms attributed to its saponins, tannins, silicic acid, and iridoids are pharmacologically plausible but have not been validated in clinical trial settings. Evidence remains at the level of traditional use and pharmacological plausibility only.

5.2 Antioxidant Activity

In vitro / laboratory evidence (moderate, consistent across studies): Strong antioxidant activity was demonstrated through DPPH, ABTS, and FRAP assays, with leaves, particularly those of G. tetrahit, exhibiting the greatest radical scavenging potential. G. tetrahit leaves had the highest DPPH radical scavenging activity with an IC₅₀ of 0.458 ± 0.03 mg/mL, demonstrating a markedly stronger antioxidant effect compared to other species and plant parts examined.

The first study of the bioactivity of G. bifida extract demonstrated that the herb has low toxicity in acute experiments and expresses antioxidant potential against free radicals in the form of DPPH•, ABTS•⁺, and superoxide radical, as well as high ferric reducing antioxidant power, oxygen radical absorbance capacity, and protective action in the carotene bleaching assay.

Limitation: All antioxidant data to date originate from in vitro laboratory assays. No human intervention trials measuring in vivo antioxidant outcomes have been published.

5.3 Neuroprotection / Acetylcholinesterase Inhibition

In vitro evidence (preliminary): Studies reinforce findings on the AChE inhibitory potential of Galeopsis spp., with earlier research identifying several bioactive metabolites with AChE inhibitory properties, including iridoid glycosides (harpagide, harpagide 8-O-acetate, ajugoside), phenylethanoid glycosides (verbascoside, isoverbascoside), flavonoid glycosides (luteolin and apigenin derivatives), and hydroxycinnamic acids (caffeoylquinic acids, e.g., chlorogenic acid).

AChE inhibition assays revealed that G. tetrahit leaves exhibited the strongest neuroprotective effects, which may be attributed to their high phenolic acid and flavonoid content.

Limitation: Evidence is entirely in vitro. Whether AChE inhibitory concentrations are achievable in vivo at physiologically relevant doses has not been investigated. No clinical studies in humans have been conducted.

5.4 Anti-Inflammatory Activity

Mechanistic / in vitro evidence (preliminary): The anti-inflammatory potential of Galeopsis extracts is attributed primarily to harpagide, verbascoside, and chlorogenic acid derivatives. Harpagide is thought to be a degradation product of harpagoside, which is responsible for devil's claw's effectiveness in treating painful degenerative joint diseases; there is evidence that these iridoids protect damaged articular cartilage from further degradation. These claims are extrapolated from the related compound harpagoside in devil's claw (Harpagophytum procumbens) and from the broader iridoid literature; no clinical trials specifically testing Galeopsis extracts for anti-inflammatory outcomes in humans have been identified.

5.5 Antimicrobial Activity

In vitro evidence (preliminary): Research has demonstrated the plant's potential to scavenge free radicals and modulate inflammatory pathways; additionally, some studies suggest mild antimicrobial effects, supporting its historical use for respiratory and skin conditions. These findings are based on laboratory screening studies; no controlled human studies have been conducted.

5.6 Liver / Gastrointestinal Applications

Ethnopharmacological evidence only: A study on G. bifida found that its extracts can be considered as low-toxic antioxidant agents and, considering the early ethnopharmacological information on its use in the treatment of liver and stomach diseases, it is assumed that the benefits are due to its high content of compounds with antioxidant and anti-inflammatory activity, such as verbascoside, 3-O-caffeoylquinic acid, luteolin, and apigenin glycosides. This is a hypothesis based on chemical composition; no clinical studies evaluating hepatic or gastrointestinal endpoints exist.

5.7 Standardization Research

A 2026 study reported the standardization of a G. tetrahit leaf extract using a fully validated UHPLC–PDA method developed according to ICH Q2(R2) requirements; leaves of wild-grown G. tetrahit collected from southwest Romania were extracted with 70% ethanol, yielding 17.28% dry extract. Standardization based on verbascoside not only supports consistency in biological activity but also enables comparisons across geographical origins, chemotypes, and harvesting seasons. This is an analytical/quality-control study, not a clinical efficacy study.

---

6. Body Systems Associated with Hempnettle

• Respiratory system: The primary traditional target; expectorant, astringent, and bronchial effects attributed to saponins, tannins, and iridoids
• Immune/inflammatory system: Anti-inflammatory and immunomodulatory activities attributed to harpagide, verbascoside, and phenolic acids in vitro
• Nervous system: AChE inhibitory activity of G. tetrahit leaf extracts suggests neuroprotective potential, currently limited to in vitro data; early pharmacological studies have indicated the presence of central nervous system (CNS) depressive, antioxidant, neuroprotective, and anticholinesterase activities
• Urinary / fluid balance: Traditional use as a diuretic for fluid retention
• Gastrointestinal system: Decoctions used in folk medicine for gastritis, stomatitis, and gastrointestinal inflammation, particularly in Eastern traditions
• Connective tissue / musculoskeletal: Silicic acid content in downy hemp-nettle is proposed to strengthen connective tissue and support cartilage tissue.
• Hepatic system: Traditional use among nomadic Asian populations for hepatic diseases

---

7. Dosage Forms and Reported Dosages

The following dosage information is drawn solely from pharmacognostic references citing traditional or official pharmaceutical guidelines. No controlled clinical trial-derived dosages exist for hempnettle.

• Drug material: "Production: Hempnettle consists of the aboveground parts of Galeopsis segetum Necker (synonym Galeopsis ochroleuca Lamarck) and is gathered in the wild during the flowering season."
• Infusion preparation: "To prepare an infusion, pour boiling water over 2 g of comminuted drug, strain after 5 minutes."
• Daily dosage: "Average daily dose: 6 g drug. One cup of the infusion may be taken several times daily and, if preferred, sweetened with honey."
• Mode of administration: "Ground and cut herb for teas and other galenical preparations for internal use."

These figures are cited from the Physician's Desk Reference for Herbal Medicines (PDR), which draws on the German pharmacopoeia tradition for Galeopsidis herba. No separate dosage ranges for extracts, tinctures, or capsule forms have been established in peer-reviewed clinical literature.

---

8. Safety Considerations

8.1 General Safety Assessment

When taken by mouth, there is not enough reliable information to know if hempnettle is safe or what the side effects might be. Regarding pregnancy and breast-feeding, there is insufficient reliable information to know if hempnettle is safe to use.

Bioactivity studies on G. bifida extract have demonstrated that the herb has low toxicity in acute animal experiments and expresses antioxidant potential in laboratory models.

8.2 Toxicological Concern: Paralysis Risk from Fruits and Seeds

A significant toxicological concern specific to the Galeopsis genus relates to its fruits and seed-derived material. There is evidence suggesting the potential for intoxication — manifesting as transient limb paralysis — following the consumption of fruits, with seed oil even being implicated, from Galeopsis spp. (G. bifida, G. ladanum, G. speciosa, and G. tetrahit). Total paralysis and other nervous disorders were reported from eating material from G. tetrahit in famine food records from China. Wikipedia's entry on the genus notes: "The plants are poisonous."

Notably, the conventional medicinal use of hempnettle employs the aerial vegetative parts and flowers (the herb, herba), not the fruits or seeds. The paralysis risk is associated primarily with fruit/seed ingestion rather than with properly prepared infusions of the aboveground flowering herb.

8.3 Chemotype and Geographic Variability

In the course of studying Siberian populations of G. bifida, the existence of two chemotypes characterized by geographical confinement was demonstrated. This phenomenon can be important when choosing locations to collect plant materials regarding specific parameters of their chemical composition. This variability means that the phytochemical content — and potentially the safety profile — of plant material may differ substantially across geographic origins.

8.4 Absence of Known Drug Interactions

No drug-herb interaction data specific to Galeopsis species have been identified in the published pharmacological or clinical literature. More evidence is needed to rate the effectiveness and safety of hempnettle for any of its current uses.

8.5 Under-Investigation Status

G. tetrahit is ethnopharmacologically significant but remains relatively under-investigated compared with other phenolic-rich Lamiaceae genera such as Phlomis, Nepeta, Stachys, or Salvia. The current evidence base is largely preclinical, consisting of in vitro chemical and bioactivity characterization studies, with no randomized controlled human trials published as of mid-2026.

---

References

• Goga et al. (2025). "Phenolic Acid Investigation and In Vitro Antioxidant and Antiacetylcholinesterase Potentials of Galeopsis spp. (Lamiaceae) from Romanian Flora." Pharmaceuticals, 18(4), 599. PMC12030362.
• Mavrodin et al. (2026). "Standardization of Romanian Galeopsis tetrahit Leaf Extract in Verbascoside Using a Validated UHPLC–PDA Method." Plants, 15(3), 461. PMC12899807.
• Olennikov DN. (2020). "Synanthropic Plants as an Underestimated Source of Bioactive Phytochemicals: A Case of Galeopsis bifida (Lamiaceae)." Plants, 9(11), 1555. PMC7696744.
• Li et al. (2021). "Verbascoside Protects Gingival Cells against High Glucose-Induced Oxidative Stress via PKC/HMGB1/RAGE/NFκB Pathway." PMC8464661.
• Wikipedia. "Galeopsis." Wikimedia Foundation.
• Native Plant Trust Go Botany. "Galeopsis tetrahit (brittle-stemmed hemp-nettle)."
• BSBI. "Galeopsis tetrahit L., Common Hemp-nettle." Botanical Society of Britain and Ireland.
• RxList. "Hempnettle: Health Benefits, Side Effects, Uses, Dose & Precautions."
• WebMD. "Hempnettle: Overview, Uses, Side Effects, Precautions, Interactions, Dosing and Reviews."
• eFlora.info. "Hemp-Nettle — Galeopsis tetrahit." (Citing PDR for Herbal Medicines.)
• Ewalia. "Downy Hemp-Nettle (Galeopsis segetum)."
• Plants For A Future (PFAF). "Galeopsis segetum — Downy Hemp Nettle."
• First Nature. "Galeopsis tetrahit, Common Hemp-nettle: identification, distribution, habitat."
• Purdue University Famine Foods. "Galeopsis tetrahit."
• ResearchGate. "Anti-inflammatory activity of verbascoside- and isoverbascoside-rich Lamiales medicinal plants." (2023)