Figwort

What is Figwort?

Consumer drug references tell people with ventricular tachycardia "Don't use figwort" (Scrophularia nodosa), yet this issue found no measured cardiac glycoside or human case report behind the warning. That gap, and the fact that most "figwort" pharmacology was done on other Scrophularia species, shape everything below.

Scrophularia nodosa is a perennial of moist, shaded and disturbed ground, native to Europe and parts of Asia, with a thick knotted rhizome, a stiff square stem up to 150 cm tall (the French Pharmacopoeia's description), and small brownish flowers that social wasps pollinate. It stays in the figwort family, Scrophulariaceae, which lost foxglove (Digitalis) and many other genera when DNA studies broke the old family apart (Olmstead and colleagues, American Journal of Botany, 2001). Western herbalism uses the dried flowering tops, sometimes the root.

Traditional Chinese medicine uses a different plant: Xuan Shen, the dried root of Scrophularia ningpoensis Hemsl., processed until its cut surface turns black. Korea's equivalent root comes partly from a third species, S. buergeriana. These roots, not the European herb, carry most of the genus's published pharmacology.

Common Names

Figwort, common figwort, knotted figwort, woodland figwort, scrofula plant, throatwort, Scrophulariae herba; Braunwurz or Knotige Braunwurz (German); scrofulaire noueuse (French). King's American Dispensatory (1898) also used "carpenter's square," a name usually given to the American S. marilandica. Some sellers use "heal-all," which is more often the common name of self-heal (Prunella vulgaris), a different plant. Xuan Shen is sold as Scrophulariae Radix, yuan shen or ningpo figwort root.

Primary Active Compounds

Iridoid glycosides lead. In field-grown S. nodosa, Sesterhenn, Distl and Wink (Plant Cell Reports, 2006) measured total iridoid glycosides at 4.88% of dry weight, with harpagoside at 1.05% in leaves, aucubin as the other major iridoid, and catalpol only in traces. The aerial parts also contain acylated catalpol esters: Miyase and Mimatsu (Journal of Natural Products, 1999) isolated 18 acylated iridoid glycosides and 9 phenylethanoid glycosides, and Stevenson and colleagues (Phytotherapy Research, 2002) isolated scropolioside A, scrophuloside A4 and scrovalentinoside from the seed pods. The phenylethanoids include verbascoside (acteoside) and angoroside A and C. A German monograph collection (medpharm Heilpflanzen, 2003) adds harpagide, acetylharpagide, the flavonoid diosmin, tannins and possible saponins. Xuan Shen root is assayed for harpagide, harpagoside, angoroside C and cinnamic acid.

Key Note

"Figwort" on a label can mean the European herb top, the Chinese root of a different species, or a homeopathic tincture made from the fresh flowering plant. They differ in plant part, species, processing and marker content, and the research on one does not transfer automatically to the others.

The European herb is a traditional remedy with chemistry and cell studies behind it and no human trial of its own.

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Primary Functions & Benefits

Figwort's reputation is as a skin and gland remedy. King's American Dispensatory (Felter and Lloyd, 1898), whose monograph covered the American variety then classed as S. nodosa var. marilandica, called it "alterative, diuretic, and anodyne," recommended it internally for scrofula, skin disease and dropsy, and externally as a fomentation or ointment for bruises, ringworm, piles and "itch," while warning that it "is very slow to produce its effects." Health Canada's current natural health product monograph for S. nodosa allows seven traditional claims for the dried herb top: diuretic, analgesic, mild laxative, and relief of symptoms of chronic skin disease, eczema, psoriasis and pruritus. Each is labeled "traditionally used in Herbal Medicine," which in Canadian law means the claim rests on historical references, not trials.

Eczema, psoriasis and itch

No controlled trial of S. nodosa in any skin condition was found for this issue. The eczema, psoriasis and pruritus claims trace to the British Herbal Pharmacopoeia (1983) and to David Hoffmann's Medical Herbalism (2003), the references Health Canada cites for them. The laboratory support is thin and indirect: three acylated catalpol esters from S. nodosa seed pods stimulated growth of human dermal fibroblasts in culture, with the effect highest at 0.78 micrograms per mL and gone at 100 micrograms per mL for two of them (Stevenson and colleagues, 2002). Fibroblast growth is relevant to wound repair, not to the immune skin disease behind eczema or psoriasis.

Wounds: the human trials are on another species

The topical trials in the genus test Scrophularia striata, an Iranian species, not S. nodosa. A team led by Bagheri (Evidence-Based Complementary and Alternative Medicine, 2022) randomized 120 patients with brain or spinal cord injury and grade 1 or 2 pressure sores into four groups of 30. By day 10, complete healing occurred in 100% of the group using S. striata hydroalcoholic extract alone, 63% of the group using the extract plus phenytoin, 27% of the phenytoin control group and none of the placebo group. Miri and colleagues (International Wound Journal, 2025) randomized 100 ostomy patients to a topical S. striata solution daily for 14 days or the clinic's usual chamomile ointment and reported greater improvement in peristomal skin with the S. striata solution (p < 0.001). Neither result tells a buyer anything about a figwort capsule.

Gums

Kerdar and colleagues (Journal of Ethnopharmacology, 2019) gave 50 adults with chronic periodontitis either an S. striata mouthwash or Irsha, an Iranian mouthwash the authors describe as a form of Listerine, for 4 weeks, and reported short-term improvement in plaque index, pocket depth and bleeding on probing with the herbal rinse, with Streptococcus mutans counts changing later.

Pain and gut spasm, in animals

In mice, a crude S. nodosa extract at 500 mg/kg reduced acetic acid writhing by 65.6% (Ahmad and colleagues, Pakistan Journal of Pharmaceutical Sciences, 2012). In isolated rabbit jejunum, the chloroform fraction relaxed the muscle by 77.37% at 15 mg/mL while the aqueous fraction contracted it by 38.56%, which the authors attributed to action at muscarinic receptors. These are the only analgesic and antispasmodic data on the European species located for this issue.

"Lymphatic" and "alterative" claims

Herbal texts call figwort a lymphatic and an alterative, the old term for a remedy that gradually corrects a disordered constitution. King's listed "enlarged lymphatics" among its specific indications. No study has measured lymph flow or lymph node size after figwort. The term survives commercially in homeopathy: medpharm's monograph names Lymphomyosot, a German homeopathic combination product, as one place S. nodosa mother tincture is used. Burdock, yellow dock, cleavers and red clover carry the other "blood purifier" stories in this archive.

Xuan Shen's separate record

Xuan Shen is a cooling root in Chinese medicine, used for sore throat, fever, constipation and swellings, and as a core herb in formulas for thyroid overactivity and diabetes. Its pharmacology is largely in rats: lower blood pressure, less heart muscle thickening after induced pressure overload or coronary ligation, liver protection and anti-inflammatory effects. The human data are formula data. A 2026 meta-analysis in the Journal of Ethnopharmacology (Li and colleagues) pooled 44 randomized trials comparing Chinese herbal formulas with conventional Western treatment for Graves' disease and listed "Radix Scrophularia" among the six most frequently used herbs; it cannot isolate the root's contribution.

Forms & Standardization

No standardized S. nodosa extract has been tested in people, so there is no reference product against which to judge any form on the shelf.

Dried herb top, cut or powdered

The form Health Canada's monograph covers: the dried flowering tops, as powder, tea or non-standardized extract in water or ethanol. US bulk herb suppliers, Mountain Rose Herbs among them, sell it as organic dried herb. No herb-top product reviewed for this issue stated a harpagoside or total iridoid content.

Tinctures and glycerites

Liquid extracts of the herb in ethanol or glycerin are sold online by small herbal brands. Historical doses for the Eclectic fluid extract and tincture appear under Special Considerations; no marker data were found for any current figwort liquid.

Homeopathic mother tincture

The French Pharmacopoeia (2007) monograph for Scrophularia nodosa for homeopathic preparations is the only official quality standard for the European species located for this issue. The source is the whole fresh flowering plant, extracted in 65% ethanol, and the mother tincture must contain at least 0.03% m/m harpagoside, assayed by HPLC at 278 nm, with an identity test on thin layer chromatography that shows harpagoside as a violet band and aucubin as a brown-violet one. Higher homeopathic dilutions made from it contain essentially none of either.

Iridoid content by species and plant part

Harpagoside, the marker shared across the genus, varies tenfold or more:

• S. nodosa, field-grown leaves: 1.05% of dry weight (Sesterhenn and colleagues, 2006)

• S. ningpoensis, leaves in July: 12.02 mg/g, about 1.2% (Xie and colleagues, Journal of Pharmaceutical and Biomedical Analysis, 2020)

• S. ningpoensis root, crude drug: 0.078% to 0.362%, with harpagide 0.277% to 0.620% (Bai et al., China Journal of Chinese Materia Medica, 2011)

For scale, the European Pharmacopoeia sets a minimum of 1.2% harpagoside for devil's claw root, the archive's harpagoside plant. Figwort leaf can approach that figure; the Chinese root, which is the part actually studied, runs well below it. Figwort's harpagoside content is not evidence that figwort does what devil's claw extracts do.

Xuan Shen root slices and processing

The root is dried by alternately sunning it and piling it for 3 to 6 days at a time, a "sweating" process that turns the interior black. Processing changes the markers: Bai and colleagues found harpagide rose 13.7% to 96.0% while harpagoside fell 11.0% to 73.9%, and Cao and colleagues (Journal of Separation Science, 2015) found processed samples lower in harpagide and harpagoside but higher in catalpol, acteoside, angoroside C and cinnamic acid. Both the Chinese Pharmacopoeia and Hong Kong's Chinese Materia Medica Standards (volume 4) require harpagide plus harpagoside of at least 0.45% on the dried root, and Hong Kong adds at least 0.03% cinnamic acid, water-soluble extractives of at least 60.0% and ethanol-soluble extractives of at least 57.0%.

Xuan Shen granules

Concentrated water extracts dried onto a carrier. Sun Ten's Xuan Shen granules list Scrophularia ningpoensis root and non-GMO corn starch; Mayway's 5738CX concentrated powder lists the root and corn-derived dextrin. Neither retailer page reviewed stated an extract ratio or a marker percentage. Decoction does not carry the markers over completely: across 15 batches of a standard Xuan Shen decoction, 70.84% of harpagide and 48.56% of harpagoside transferred from root to liquid (Xu et al., China Journal of Chinese Materia Medica, 2019).

Multi-herb formulas

Most Xuan Shen is taken in formulas. Zengye granule, listed in the Chinese Pharmacopoeia, combines Xuan Shen, ophiopogon root (Mai Dong) and rehmannia root (Sheng Di) in a ratio of 1.0 to 0.8 to 0.8. Simiao Yong'an decoction combines honeysuckle flower, Xuan Shen, dong quai root and licorice.

Food Sources

Figwort is not a food, and no cuisine uses S. nodosa or S. ningpoensis. Exposure comes through herbal tea or tincture of the European herb top, Chinese decoctions, granules and patent formulas containing Xuan Shen root, homeopathic products, and topical ointments. The iridoids themselves are not unique to figwort: aucubin occurs in ribwort plantain (Plantago lanceolata), and catalpol is a principal iridoid of rehmannia root, but nobody eats those for their iridoids either.

Who Should Take Figwort

No group has been shown in a human trial to benefit from taking S. nodosa by mouth, so no one can be told with evidence that they should.

A person with eczema or psoriasis is relying on Eclectic-era practice and the 1983 British Herbal Pharmacopoeia, which is what Health Canada's traditional claims rest on. A person with a slow-healing wound is relying on trials of a different species (S. striata) applied to the skin, not swallowed. A person looking for a "lymphatic cleanse" is relying on a word that no measurement supports.

The realistic candidate is an adult who is not pregnant or breastfeeding, takes no lithium, diuretic, diabetes drug or heart rhythm medicine, and wants to try a traditional herb for minor skin complaints while understanding that nothing has been proven. Xuan Shen is a different decision, normally made with a licensed Chinese medicine practitioner who prescribes it inside a formula.

Who Should AVOID or Use Caution

Contraindications

• During pregnancy. There are no reproductive toxicity studies of S. nodosa or Xuan Shen. King's American Dispensatory (1898) recorded root decoctions taken "to restore the lochial discharge when suppressed" and to relieve painful menstruation, a uterine reputation (owned in this archive by False Unicorn Root) that argues against use in pregnancy. Health Canada requires labels to tell pregnant women to consult a practitioner first; RxList, drawing on the Natural Medicines database, says to avoid it.

• Breastfeeding, for the same absence of data.

• Children. Health Canada's monograph covers adults 18 and over only, and no pediatric data exist.

• Anyone using figwort in place of treatment for a diagnosed heart rhythm disorder, heart failure, thyroid disease or diabetes. None of the animal findings described in this issue supports substitution.

Use Caution

• Heart disease of any kind. Health Canada requires labels to say to ask a health care practitioner "before use if you have heart disease," citing Brinker (2010) and Hoffmann (2003). The underlying claim is weak (see Critical Safety Point), but extracts of related species slow the heart rate in rats, and no study has tested figwort in people with heart disease in either direction.

• People taking lithium. Natural Medicines-derived references warn that figwort "might decrease how well the body gets rid of lithium," reasoning from its traditional diuretic action. No figwort and lithium study exists, but lithium's narrow margin makes the theoretical risk worth respecting.

• People taking diuretics such as furosemide, hydrochlorothiazide, chlorthalidone or chlorothiazide, for the same reason: an added diuretic effect could lower potassium further.

• People with diabetes. The same references say figwort "might affect blood sugar control." No human glucose data exist for figwort; the related animal work is on Xuan Shen.

• People with loose stools or a sensitive gut. Health Canada allows a "mild laxative" claim, and Chinese practice says not to use Xuan Shen in those with "spleen deficiency and loose stools."

Critical Safety Point

The specific warning on ventricular tachycardia ("Don't use figwort if you have this condition"), which RxList prints and which circulates on store and practitioner sites, could not be traced to any measured cardiac glycoside in a Scrophularia species, any electrocardiogram study, or any human case. The sources RxList lists for its figwort page are three late twentieth century reference books (Newall, Anderson and Phillipson, 1996; the American Herbal Products Association's Botanical Safety Handbook, 1997; the PDR for Herbal Medicines, 1998), and Health Canada attributes its broader heart-disease caution to Brinker (2010) and Hoffmann (2003). This issue could not open those books to see what each one cites. The idea is older and wider than one book, though: the 2017 genus review records traditional use of several Scrophularia species as "heart stimulant," a 2012 paper on S. nodosa calls it a "cardiac stimulant" without testing that, and a Greek university plant database, citing 1981 popular guides, says "Tachycardia may be observed." What could be checked is the chemistry a digitalis-like hazard would need, and it is not there. That does not make figwort inert on the heart: related species slow the heart rate in animal studies (see How Figwort Works). Being unable to find a hazard is not the same as showing safety: ventricular tachycardia is a medical emergency in its own right, nobody with it should be self-treating with any herb, and the absence of a figwort study in heart patients cuts both ways. The practical rule is unchanged even though the stated reason is weak. If you have a heart rhythm disorder or take an antiarrhythmic drug, digoxin or a beta blocker, do not add figwort without your cardiologist's agreement, and treat any new palpitations, fainting or chest discomfort after starting it as a reason to stop and be seen.

Recommended Dosages

No trial has established an effective oral dose of S. nodosa for any condition, so no dose is recommended here. What follows describes what regulators allow labels to print and what that amount contains.

Dried herb top

Health Canada's monograph allows licensed products for adults to provide 0.2 to 8 grams of dried herb top per day, as powder, tea, decoction, tincture or other non-standardized extract. That range was assembled from four herbal references (Hoffmann, 2003; Bartram, 1998; the British Herbal Pharmacopoeia, 1983; and a 1983 reprint of King's American Dispensatory), not from a dose-finding study. If the herb matched the 1.05% harpagoside measured in field-grown leaves, 8 g would contain about 84 mg; stems and flowers carry less, and no product reviewed here stated its content.

Tinctures and glycerites

No modern product reviewed for this issue gave a herb-equivalent dose that could be checked against the Health Canada range. A label that lists only "drops" of an unstated-ratio extract cannot be converted into grams of herb.

Xuan Shen granules and root

Practitioner products. The pharmacopoeial root quantity, with its context, sits under Special Considerations, because it is a prescription amount for a different species and not a supplement dose.

Homeopathic products

Dilutions of the mother tincture contain no measurable harpagoside and are outside the scope of a herbal dose.

Duration

Health Canada restricts products making the diuretic claim to occasional use. No duration of continuous oral use has been studied in humans for either species.

Timing & Administration

There are no human pharmacokinetic studies of S. nodosa, so nothing is known about absorption, timing relative to meals, or time of day. The one oral pharmacokinetic figure in the genus comes from rats: angoroside C, a Xuan Shen phenylethanoid, peaked within 15 minutes, had an elimination half-life of 1.26 hours and an oral bioavailability of about 2.1% at 100 mg/kg (Zhang and colleagues, Frontiers in Pharmacology, 2018).

Xuan Shen is traditionally decocted, and the standard decoction extracts only about half of the root's harpagoside (48.56%) against about 70.84% of its harpagide. A home tea of the European herb top is an infusion, not a decoction, and no extraction data exist for it.

For anyone on lithium or a diuretic who decides to use figwort anyway, timing does not solve the theoretical problem: the concern is the body's handling of water and salt, not contact in the stomach, so spacing doses apart offers no protection.

Timeline of Effects

Each time point below comes from one specific study and should not be read as a plan for taking anything; none involves S. nodosa taken by mouth.

Topical S. striata in people

Complete healing of grade 1 and 2 pressure sores by day 10 in the extract-only group (Bagheri and colleagues, 2022); peristomal skin assessed after 14 days of daily application and at 21 days (Miri and colleagues, 2025); periodontal measures at 2 and 4 weeks of mouthwash use (Kerdar and colleagues, 2019).

Xuan Shen extracts in rats

Heart remodeling studies ran 4 weeks (Gu and colleagues, Pharmazie, 2010), 8 weeks (Gu and Chen, 2008), 14 weeks (Huang and colleagues, Phytomedicine, 2011) and 21 weeks (Zhang and colleagues, SpringerPlus, 2016). These describe how long rat experiments lasted, not when a person would notice anything.

Traditional expectation

King's American Dispensatory (1898) described the alterative effect as "very slow to produce its effects," without a time frame.

When to conclude it is not working

Because there is no human benchmark for oral figwort, no time point makes a lack of response informative. For a skin condition, a reasonable personal test is a fixed period with photographs and a symptom diary, after which a dermatologist's assessment is worth more than any further weeks of the herb.

Benefits of Taking Figwort

For oral S. nodosa, no benefit has been demonstrated in people. The case for it is a list of laboratory and animal signals: catalpol esters from its seed pods that stimulate cultured human skin fibroblasts, a crude extract that reduced writhing in mice by 65.6% at 500 mg/kg, a chloroform fraction that relaxed rabbit gut muscle, and finely sieved herb powders that lowered markers of oxidative stress in mouse spleen cells at 250 micrograms per mL (Soualeh and colleagues, International Journal for Vitamin and Nutrition Research, 2019). Root extracts inhibited azole-resistant Candida tropicalis and Candida albicans in a Ukrainian screening of 166 plant extracts (Ohiienko and colleagues, Wiadomości Lekarskie, 2023).

The genus does have human results, all for other species or for topical use: S. striata extracts on pressure sores, peristomal skin and gums. Xuan Shen has a large body of rat cardiovascular and metabolic work and appears in Chinese formula trials, where its own share of any effect cannot be separated.

The honest summary is that figwort is a traditional skin herb with a plausible chemistry and no human evidence of its own.

Potential Negatives & Side Effects

What has been reported in people

No published adverse event report naming S. nodosa taken by mouth was found in PubMed for this issue. The two adverse effects official texts list are both predictable from the traditional claims: Health Canada requires a "diuretic effect may occur" statement on products that do not already make a diuretic claim, and the allowed "mild laxative" claim implies looser stools at higher intakes. Neither effect has been measured. A PubMed search for studies measuring urine output after figwort found none.

Historical toxicity claims

King's American Dispensatory (1898) reported, citing van de Moer (1895), that "the aqueous and alcoholic extracts of the herb and the seeds are poisonous." No dose, species or animal model is given in that summary, and the original 1895 report could not be located for this issue. It is the oldest toxicity statement in the record and should not be dismissed simply because it is old; it has also never been followed up.

Xuan Shen injections

Che and colleagues (Immunopharmacology and Immunotoxicology, 2018) wrote that Xuan Shen has been used as an injectable Chinese medicine and that allergic responses to such injections "are frequently reported," and then showed that harpagoside itself caused paw swelling and histamine release in mice and mast cell degranulation in culture without involving IgE. That makes harpagoside a candidate for allergy-like reactions by a non-immune route. Injectables are not supplements, and no oral case has been described.

Formula toxicity in rats

Zengye granule (Xuan Shen, ophiopogon and rehmannia) caused no toxicity in rats at a single 10 g/kg dose or at 2.5 g/kg a day for 30 days, but produced slight kidney and spleen toxicity at 5 and 10 g/kg a day, with raised white cell counts and ALT in female rats (Lv and colleagues, Journal of Ethnopharmacology, 2023).

Deficiency Symptoms

What figwort addresses

No deficiency. The body has no requirement for harpagoside, aucubin or any other figwort constituent, and none is measured in blood as a marker of health. Figwort is taken for symptoms, mainly of the skin, and the targets are inflammatory or infectious processes, not a shortfall.

Bottom line

No figwort deficiency state exists, and no test measures figwort status. The only meaningful monitoring for a figwort user is the ordinary kind: potassium for someone on a diuretic, lithium levels for someone on lithium, glucose for someone with diabetes.

Toxicity Symptoms

At high intake

No human poisoning from S. nodosa was found in the published record. The animal data are sparse and mostly on other preparations. A crude S. nodosa extract and its fractions showed no toxicity in the brine shrimp test at any concentration used (Ahmad and colleagues, 2012), a screening assay that says little about humans. The rat data on Zengye granule set a no-effect level of 2.5 g/kg a day for 30 days for that three-herb formula. For the European herb itself, no repeated-dose oral toxicity study in animals was located, and the 1895 claim King's cites, that its extracts are "poisonous," stands unreplicated in either direction.

Signs to reduce or stop

Stop and seek care for palpitations, a racing or irregular pulse, fainting or near-fainting, or chest discomfort, whatever their cause. Stop and contact a clinician for muscle cramps, weakness or unusual fatigue if you also take a diuretic (possible low potassium); for tremor, unsteadiness, confusion, vomiting or diarrhea if you take lithium (possible rising lithium level); and for shakiness, sweating or confusion if you take a diabetes drug. Persistent diarrhea, a rash, hives or facial swelling are also reasons to stop.

General note

Neither species has reproductive toxicity, carcinogenicity or genotoxicity studies in the sources reviewed for this issue. That gap, rather than any positive finding, is why pregnancy is listed under Contraindications.

How Figwort Works

Iridoid glycosides: the chemical signature

Iridoids are monoterpenes built on a cyclopentane ring fused to an oxygen-containing pyran ring, usually stored in the plant bound to glucose. The ones in figwort fall into three groups. Simple glycosides: aucubin, catalpol and harpagide. Cinnamic acid esters: harpagoside is harpagide carrying a cinnamoyl group. Acylated catalpols: catalpol linked through a rhamnose sugar to acetyl and methoxycinnamoyl groups, the scropoliosides and their relatives, which the 2017 review by Pasdaran and Hamedi (Pharmaceutical Biology) describes as the most structurally varied iridoid group in the genus. The review counted 72 iridoid glycosides from the genus. Plants appear to use them as feeding deterrents; weevils of the genus Cionus that live on figwort store aucubin and catalpol from their host (Baden and colleagues, Journal of Chemical Ecology, 2013).

Anti-inflammatory signaling, in cells

The best mechanistic data on acylated catalpols come from S. dentata, a Chinese species: scropolioside B inhibited activity of the inflammatory transcription factor NF-kappa-B with an IC50 of 1.02 micromolar, while catalpol itself did not (Zhu and colleagues, Mediators of Inflammation, 2014). Whether S. nodosa's own scropolioside A and scrophuloside A4 reach such concentrations in human skin or blood after a cup of tea is unknown. Phenylethanoids such as verbascoside and angoroside C add antioxidant and anti-inflammatory activity in cell assays, but angoroside C had an oral bioavailability of about 2.1% in rats.

Smooth muscle

The spasmolytic action of S. nodosa's chloroform fraction on rabbit jejunum (77.37% relaxation at 15 mg/mL) behaved like antagonism at muscarinic acetylcholine receptors, the authors concluded, while the water fraction had the opposite, contracting effect. The same group isolated seven flavonoids from the chloroform fraction, including centaurein and serpyllin, but did not establish which compound was responsible.

What a cardiac glycoside is, and why figwort does not fit

A cardiac glycoside is a steroid with a five- or six-membered lactone ring (a cardenolide such as digoxin from foxglove, or a bufadienolide such as bufalin from toad venom) attached to sugars. It works by blocking the sodium-potassium pump in heart muscle cells, which raises calcium inside the cell, strengthens contraction and slows conduction, and in excess triggers dangerous rhythms, including ventricular tachycardia. That is the pharmacology a cardioactive-herb warning about ventricular tachycardia implies. The 204 compounds tabulated across the genus by Pasdaran and Hamedi include iridoids, phenylethanoids, flavonoids, phenolic acids, triterpene saponins, sterols, diterpenes and a few alkaloids, and no cardenolide or bufadienolide. A review of S. ningpoensis listing more than 162 compounds (Ren and colleagues, Journal of Ethnopharmacology, 2020) names iridoids, phenylpropanoid glycosides, organic acids, volatile oils, terpenoids, sugars, flavonoids, sterols and saponins, again with no cardiac glycoside. In October 2026 a PubMed search pairing Scrophularia with cardiac glycoside, cardenolide, bufadienolide, bufalin, digoxin or "cardioactive" returned two records. One is the 2012 Ahmad paper, whose abstract says S. nodosa "contains saponins, cardioactive glycosides, flavonoids" but which isolated only seven flavonoids. The other is a 2025 Chinese study that used Xuan Shen polysaccharide as a nanoparticle carrier for bufalin, the toad compound, against liver cancer cells (Zheng et al., China Journal of Chinese Materia Medica); there the cardiac steroid was added by the chemists.

What the measured cardiac pharmacology shows instead

Where Scrophularia has been tested on heart tissue, in other species and in animals, the results do not fit a toxic digitalis-like profile, but they do show activity. Iridoid and aromatic glycosides from Xuan Shen root, harpagoside among them, inhibited the potassium-induced rise in intracellular calcium in rat heart muscle cells at 100 micromolar (Chen and colleagues, Chemistry and Biodiversity, 2008), the reverse of what a cardiac glycoside does. Xuan Shen extracts lowered heart rate and blood pressure in pressure-overloaded rats (Gu and Chen, 2008). In isolated rat hearts subjected to 30 minutes of ischemia, a methanol extract of the Iranian S. frigida reduced the number and duration of ventricular tachycardia episodes during ischemia and, at the highest concentration (10 micrograms per mL), slowed the heart rate (Garjani and colleagues, Iranian Journal of Pharmaceutical Research, 2017). None of this was done with S. nodosa, and none of it is a human result. The arrhythmia findings point away from what a ventricular tachycardia warning predicts, but heart-rate slowing is also what digoxin and beta blockers do, so an additive effect cannot be ruled out.

Synergistic Supplements

Xuan Shen inside Chinese formulas

Xuan Shen is almost never prescribed alone. Its classic partners are ophiopogon root and rehmannia root (Zengye, for dry mouth, dry throat and constipation in "yin deficiency"), and honeysuckle flower, dong quai and licorice (Simiao Yong'an, one of the 100 formulas in China's first catalogue of ancient classic prescriptions). In rats with diet- and streptozotocin-induced diabetes, a Xuan Shen and Atractylodes pair added to metformin lowered post-meal glucose and inflammation more than metformin alone (Guo and colleagues, Frontiers in Microbiology, 2022). No human trial isolates what Xuan Shen adds to any of these pairings.

Western blends

In Western practice figwort appears in "skin" and "blood purifier" blends alongside burdock, yellow dock, cleavers and red clover. No combination has been tested, and stacking several traditionally diuretic or laxative herbs adds the side effects without adding evidence.

What not to stack

Licorice, which lowers potassium with regular use, is a poor partner for anyone already taking a diuretic, and it is one of the four herbs in Simiao Yong'an. Combining figwort with devil's claw or other harpagoside sources has no rationale and no safety data. Other herbs sold as diuretics, such as dandelion leaf, juniper or horsetail, compound the lithium and potassium concerns.

Interactions & What NOT to Take

No human drug interaction study of S. nodosa or Xuan Shen was found for this issue. Every interaction below is theoretical, based on traditional actions or animal data, and is listed because the drugs involved have narrow margins.

Lithium

Lithium carbonate and lithium citrate. If figwort acts as a diuretic, it could reduce lithium clearance and raise blood levels; RxList, drawing on Natural Medicines, rates the interaction moderate. Avoid, or combine only with lithium level monitoring arranged by the prescriber.

Diuretics

Furosemide (Lasix), bumetanide, torsemide, hydrochlorothiazide, chlorthalidone, chlorothiazide and indapamide. Possible additive fluid and potassium loss.

Diabetes medicines

Metformin, insulin, glipizide, glyburide, glimepiride and pioglitazone. Reviews describe antidiabetic effects of Xuan Shen in laboratory and animal models (Song and colleagues, Frontiers in Endocrinology, 2025); in diabetic rats a Xuan Shen pair plus metformin lowered post-meal glucose more than metformin alone (Guo and colleagues, 2022); and Natural Medicines-derived references advise glucose monitoring. No human glucose data exist for S. nodosa.

Heart rhythm and heart failure drugs

Digoxin, amiodarone, flecainide, propafenone, sotalol, dofetilide, and beta blockers such as metoprolol and bisoprolol. There is no measured cardiac glycoside in figwort to add to digoxin, but the animal data on Xuan Shen and S. frigida point toward slower heart rates, which could add to the rate-slowing effect of digoxin, beta blockers or amiodarone. No one has studied the combination. Do not add figwort to these drugs without the prescribing cardiologist's agreement.

Veratrum (li lu)

Chinese medicine's classic "eighteen incompatibilities" rule forbids combining any of the "shen" roots, Xuan Shen among them, with Veratrum root, which is itself a toxic plant that slows the heart and lowers blood pressure. No one should be taking Veratrum outside specialist practice in any case.

Quality, Testing & Adulteration

Species substitution

The French Pharmacopoeia's homeopathic monograph warns specifically about water figwort, Scrophularia aquatica: in translation, a hollow stem and leaves with winged petioles signal adulteration. S. nodosa has a stiff, four-angled stem that is not hollow. On the Asian side, Korean sources define Scrophulariae Radix as the root of S. ningpoensis or S. buergeriana, and related species differ in marker content: Nam and colleagues (Plants, 2020) measured harpagoside at 1.94, 5.50 and 6.47 mg/g in three Korean Scrophularia species, S. buergeriana among them, and compared their morphology.

Processing changes the chemistry

Because sweating and drying shift harpagoside downward and catalpol, acteoside and cinnamic acid upward, two lots of genuine Xuan Shen can assay differently depending on how they were processed. That is why the Chinese and Hong Kong standards set a combined harpagide plus harpagoside minimum (0.45%) rather than a harpagoside figure alone.

Heavy metals

Gong, Ren and Zhang (Toxics, 2024) studied soil and plants in a Xuan Shen production area and found lead the dominant soil contaminant, with average single-factor pollution indices of 0.94 outside the root zone and 0.89 within it, just under 1.0, the usual pollution threshold. The calculated health risk from eating the leaves and stems was more than ten times that from the root, though the authors found no significant carcinogenic risk from either. Leaves and stems are not the official drug, but Xie and colleagues (2020) proposed developing them as a medicinal resource, which would raise the stakes. Hong Kong's standard requires the root to pass its general limits for metals, pesticides, mycotoxins and sulfur dioxide residues, and caps foreign matter at 1.0%, total ash at 5.0% and water at 16.0%.

Third-party testing

None of the figwort or Xuan Shen products reviewed for this issue carried a USP Verified, NSF Certified or ConsumerLab seal, and none of the retailer pages (Sun Ten granules, Mayway 5738CX) published contaminant or marker results. For the European herb, no USP or European Pharmacopoeia monograph was found to test against; the only official assay located for S. nodosa is the French homeopathic one.

How to judge a lot before you buy

Ask the seller for the certificate of analysis for the specific lot. A credible one gives the full Latin binomial and the plant part (S. nodosa herb top, or S. ningpoensis root), an identity method such as thin layer chromatography against harpagoside and aucubin or DNA barcoding, a measured harpagoside figure (and for Xuan Shen, harpagide plus harpagoside against the 0.45% minimum), and results for lead, cadmium, arsenic and mercury in mg/kg, each beside the limit it was judged against. Then check what you can see. The Supplement Facts panel should name the species, not just "figwort" or "Scrophularia." A product that says "Scrophularia root" with no species could be any of several Asian species. A liquid extract should state its ratio and solvent. Genuine Xuan Shen slices are grayish yellow to grayish brown outside, black and slightly glossy in cross section, smell faintly of caramel and taste slightly bitter, per the Hong Kong standard.

Special Considerations

Practitioner and historical quantities, in context

These figures describe historical or prescription practice and are not supplement recommendations. Xuan Shen root: 9 to 15 g a day in decoction, the quantity given in Chinese pharmacopoeial and materia medica references, prescribed by practitioners, usually inside a formula. King's American Dispensatory (1898): infusion or syrup, 2 to 4 fluid ounces; fluid extract, 30 to 60 drops; strong tincture, 10 to 40 drops. Ellingwood's American Materia Medica (1919): "specific scrophularia," 5 to 30 drops. None of these was established in a trial, and the Eclectic preparations no longer exist in their original form.

Regulatory status

United States: sold as a dietary supplement ingredient under DSHEA, with no FDA review of efficacy or safety. Canada: a Health Canada natural health product monograph for S. nodosa allows seven traditional claims at 0.2 to 8 g of herb top a day for adults, with pregnancy and heart disease consultation statements. Germany: the medpharm monograph collection (2003) records no Commission E monograph for figwort herb and rates the information "insufficient" for an evaluation. France: the 2007 Pharmacopoeia covers S. nodosa only as homeopathic raw material. China and Hong Kong: Xuan Shen root is an official medicine with assay standards.

Name confusion

"Heal-all" is the usual name of self-heal (Prunella vulgaris), and "carpenter's square" usually means the American S. marilandica. If a product uses one of these names, check the Latin binomial before assuming it is S. nodosa.

Research Status & Evidence Quality

Tier 1, chemistry (strongest)

The iridoid and phenylethanoid composition of S. nodosa and Xuan Shen is well documented by isolation and HPLC studies, with measured contents for harpagoside, aucubin and harpagide, an official French homeopathic assay and Chinese and Hong Kong root standards. The 2017 genus review found 204 compounds and no cardiac glycoside.

Tier 2, topical human trials of another species

Three randomized trials of S. striata, an Iranian figwort, on pressure sores (120 patients, double-blind), peristomal skin (100 patients, convenience sample, chamomile comparator) and periodontitis (50 patients), each small and from a single country. They support the genus's wound and gum reputation; they do not test S. nodosa or oral use.

Tier 3, Xuan Shen in animals and formulas

Rat and mouse studies of heart remodeling, blood pressure, liver protection, inflammation and glucose, plus Chinese formula trials. The largest human dataset is observational: a target trial emulation using hospital records of 3,302 hypertensive patients found that the 359 given Xuan Shen Yishen decoction alongside antihypertensives reached intensive blood pressure targets more often (17.5% against 8.09%; odds ratio 2.29), with fewer readmissions at 6 months (Wang and colleagues, Chinese Journal of Integrative Medicine, 2025). Patients were not randomized, and the decoction contains more than one herb.

Tier 4, oral S. nodosa

Mouse writhing, rabbit gut muscle, mouse spleen cells, fungal cultures and fibroblast cultures. No human trial found.

The cardiac caution

No measured cardiac glycoside, no electrocardiogram study and no human case report located. The earliest digitalis comparison located is a single 1898 sentence about an unnamed extract; a looser "heart stimulant" reputation runs through traditional sources. Rat and isolated-heart studies of related species show heart-rate slowing.

Research Limitations

Pasdaran and Hamedi noted that only 17 of about 350 Scrophularia species have been studied in any detail and that they "could not find any clinical trials" on the genus's biological activities. Most pharmacology uses Xuan Shen root, while most Western products contain S. nodosa herb top. Almost no study reports the marker content of its test material. Missing entirely: human pharmacokinetic data, interaction studies, reproductive or carcinogenicity studies and any survey of US figwort products. This issue could not read the late twentieth century reference books that carry the ventricular tachycardia wording, so the step at which "resembling digitalis" became a ventricular tachycardia warning remains untraced.

Summary & Key Takeaways

Bottom Line

Figwort is a traditional European skin herb whose name is shared by a Chinese medicinal root of a different species, and almost all of the research belongs to that root or to an Iranian relative used on wounds. The European plant contains measurable iridoids, including about 1% harpagoside in its leaves, and has no human trial of its own. Its best-known warning, against use in ventricular tachycardia, rests on no measured cardiac glycoside and no reported case; the earliest digitalis comparison located is an 1898 remark about an unnamed powder.

Key Safety Points

• Avoid in pregnancy and while breastfeeding, and do not give it to children.

• If you take lithium, a diuretic or a diabetes drug, do not start figwort without your prescriber, because its traditional diuretic and reported glucose effects could matter for narrow-margin drugs.

• If you have any heart rhythm disorder or take digoxin, an antiarrhythmic or a beta blocker, do not add figwort without your cardiologist; the warning's evidence is weak, but so is the evidence of safety.

• Check that the label names the species and plant part; S. nodosa herb and S. ningpoensis root are different products.

• Stop for palpitations, fainting, cramps or weakness, persistent diarrhea, or any allergic reaction.

Special Note

A weak warning is still a warning until someone tests it. The appropriate response to this issue's finding is not "figwort is safe for the heart," which nobody has shown, but a request: anyone selling figwort, or any reference that prints the ventricular tachycardia line, should be able to say what measurement it rests on. On the evidence located for this issue, there is none.

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Researched and drafted with AI assistance. Every claim verified against primary sources and human-reviewed before publication. Last reviewed: October 26, 2026. Corrections: reply to any issue.

Nothing in this issue is medical advice; it is written for education. If you take lithium, a diuretic, a diabetes medicine or any heart medicine, have a heart rhythm disorder or another diagnosed condition, or are pregnant or breastfeeding, talk to a clinician before taking figwort or changing anything.