Centaury

Centaurium erythraea Rafn belongs to Gentianaceae, the gentian family, and was published by Rafn in a flora of Denmark and Holstein in 1800 (International Plant Names Index, via Kew’s Plants of the World Online). Grieve notes that it was earlier placed in Gentiana as Gentiana centaurium, and it has been sold and studied under several other names: Erythraea centaurium, a genus name the Flora of North America (FNA) treats as illegitimate, and Centaurium umbellatum and C. minus, which FNA describes as invalidly published or misapplied names for this species. Kew accepts C. erythraea with a native range from the Azores and Morocco through Europe to southwestern Siberia and Iran, plus Yemen. It has spread well beyond that: FNA records it as introduced in parts of Canada and the United States, Central and South America, New Zealand, and Australia, and notes that North America’s own native “centauries” have been moved to a separate genus, Zeltnera. The species is variable. EMA’s assessment report notes that hybridization is frequent and that C. erythraea in the broad sense (sensu lato, or s.l.) is an unresolved group of plants ranging from diploid to hexaploid, which is why the European monograph covers the species “s.l.”

It is a small, upright herb, 3 to 60 cm tall in FNA’s measurements, and it often still has a rosette of basal leaves when it flowers. Grieve describes a stiff, square stem with smaller paired leaves, branching near the top into flat-topped clusters of rose-pink, star-shaped flowers. FNA gives the corolla as 10 to 17 mm long, pink to rose-violet or occasionally white, with a whitish eye, and notes that the anthers twist into a spiral after shedding their pollen, a detail Grieve also mentions. The flowers keep short hours. Grieve wrote that they open only in fine weather and not after midday, and quoted the Elizabethan herbalist John Gerard on flowers that open after sunrise and shut again toward evening. Plants flower from summer into early fall (FNA). Grieve recorded that the whole herb was gathered in July, just as it came into flower, and the European Pharmacopoeia, revised in July 2024, defines the medicinal herb as the whole or fragmented dried flowering aerial parts of C. erythraea s.l., after deleting two related species from its definition (EMA addendum 2026).

In Britain, the Botanical Society of Britain and Ireland (BSBI) describes centaury as a biennial of short, open grassland on nutrient-poor, freely drained soils, from calcareous to mildly acidic, and also of sand dunes, woodland rides, and disturbed ground. It is assessed as Least Concern, though it has become less frequent locally because of agricultural improvement and relaxed grazing. Grieve noted that it grows in dry pastures and on chalky cliffs and is hard to cultivate. Chemically, EMA’s assessment report describes secoiridoid glycosides as the characteristic bitter compounds, about 75% of them swertiamarin, with smaller amounts of gentiopicroside and sweroside and the far more bitter centapicrin; because of centapicrin esters, the fruits are more bitter than the flowers, leaves, or stems. The herb also contains methoxylated xanthones such as eustomin, phenolic acids, oleanolic acid, plant sterols, and the alkaloid gentianine. Where it grows matters: a Polish survey of plants from polluted industrial regions found centaury among those with the highest cadmium, cobalt, and zinc levels, and its authors urged careful choice of collection sites (EMA).

Centaury’s name points back to the centaur Chiron. FNA explains that the genus name comes from the Greek kentauros, an allusion to Chiron. In his Natural History, written in the first century AD, Pliny the Elder tells that centaury cured Chiron when an arrow of Hercules fell on his foot, but the plant he describes in that chapter is a large one with a reddish root, which his nineteenth-century translators identified as a different plant, the greater centaury. In the next chapter Pliny describes a second, small-leaved centaury about a palm high, which the translators identified as this species. He wrote that in Italy it was called “gall of the earth” because of its extreme bitterness, and that the Gauls called it exacum because it purged harmful matter through the bowels. Grieve attached the Chiron story to the small plant, recording the old genus name Chironia, and explained that the later name Erythraea comes from the Greek erythros, red, for the color of the flowers. English names in her account include feverwort, felwort, Christ’s ladder, and centaury gentian.

For centuries centaury was valued above all as a bitter and a fever remedy. Grieve records that Saxon herbalists prescribed it largely for snakebites and other poisons, that it was long celebrated for curing intermittent fevers, which explains the name feverwort, and that it was an ingredient of the Portland Powder once taken for gout. She quotes Nicholas Culpeper’s seventeenth-century verdict, “’Tis very wholesome, but not very toothsome,” along with his recommendations for dropsy, worms, and the bites of adders. In her own day it was used for dyspepsia, especially languid digestion with heartburn after food, and was combined with barberry bark for jaundice. German and Dutch handbooks summarized by EMA tell a similar story. Madaus (1938) recorded its old use as a febrifuge, for painful periods, and as a sedative, and called it the best remedy for a burning stomach; Kneipp (1935) credited it with blood-cleansing properties; and Steinmetz (1954) described it as a bitter stomach remedy and febrifuge for chlorosis and jaundice that “purifies the blood, promotes the menses and improves the appetite.” Bisset (1994) described its use as a bitter to stimulate the appetite and gastric secretion, especially in chronic indigestion.

Centaury moved from folk practice into official pharmacy. EMA notes that it appeared in the Dutch pharmacopoeia of 1889 and the German pharmacopoeia (DAB 6) of 1936, among others, and today it has its own European Pharmacopoeia monograph. Germany’s Commission E published a monograph in 1988, revised in 1990, approving about 6 g a day for loss of appetite and indigestion. EMA’s herbal committee adopted its current European monograph in November 2015 and, in a periodic review adopted in March 2026, found no reason to revise it. In 2014 Germany reported 191 herbal teas containing centaury, and Poland had registered single-herb centaury teas in 1995 and 2000. The urinary combination is more recent: Canephron N was approved in 28 countries by 2018, and EMA recorded similar three-herb tablets registered as traditional medicines in Bulgaria and other EU states. Bitterness also put centaury into drinks. US food regulations allow centaury only in alcoholic beverages, and a review of vermouth production by Panesar and colleagues (Natural Product Radiance 2009) lists European centaury among the herbs used to flavor vermouth.

Centaury is a textbook bitter. The European Pharmacopoeia defines a bitterness value as the reciprocal of the dilution at which a substance still tastes bitter, with quinine hydrochloride set at 200,000 for comparison; Commission E required centaury to reach at least 2,000. EMA’s assessment report puts the bitterness value of sweroside at about 12,000 and of centapicrin at about 4,000,000. The traditional explanation, which EMA cites from the pharmacognosy textbook of Evans (1996), is that bitter compounds stimulate the taste nerves in the mouth and so reflexively increase the secretion of gastric juice and bile. Commission E likewise lists increased gastric juice secretion as centaury’s action. This is why bitters are taken shortly before meals, and it is also the reasoning behind the peptic ulcer contraindication. EMA’s summary of its conclusions notes that laboratory studies suggest an appetite- and digestion-stimulating effect, but that the data are very limited. Little is known about what happens after centaury is swallowed: EMA found no pharmacokinetic data, so it is unknown how much swertiamarin or its relatives are absorbed or how the body breaks them down.

Laboratory and animal studies summarized by EMA point in several directions, mostly at doses far from a cup of tea. Swertiamarin had anticholinergic, antispasmodic effects on isolated rat colon, and gentianine protected against ulcers and reduced gastric secretion in rats. Centaury extracts reduced chemically induced paw swelling in rats by about 40% at 100 mg/kg, increased urine output in rats in a study by Haloui and colleagues (2000), protected rat livers against acetaminophen poisoning, and protected rat stomachs against aspirin-induced ulcers. Several rodent studies reported lower blood sugar in diabetic animals. In test tubes, swertiamarin and sweroside showed antibacterial activity, including against Escherichia coli (E. coli), the commonest cause of bladder infections, and the xanthone eustomin was antimutagenic. None of these effects has been confirmed in people. EMA did not treat them as evidence of clinical benefit, and its monograph rests on traditional use alone.

For Canephron N, trial authors describe a mix of effects seen in laboratory and animal work, including anti-inflammatory, antispasmodic, pain-relieving, mildly diuretic, and antibacterial actions (Wagenlehner and colleagues 2018). Sabadash and Shulyak (Clinical Phytoscience 2017) summarize in vitro studies reporting bactericidal and bacteriostatic effects on urinary pathogens and reduced bacterial adhesion to the bladder lining, and they cite Haloui’s rat study for the mild diuresis. In a predefined subgroup of the large fosfomycin trial, urine levels of interleukin-8, an inflammation signal, fell significantly in women taking Canephron N, and both interleukin-6 and interleukin-8 fell significantly with fosfomycin (Butler and colleagues, Urologia Internationalis 2023). Which herb contributes what is not known. Centaury’s share of each tablet is 18 mg of powdered herb, a small fraction of the 1 to 4 g that EMA lists for a single cup of centaury tea, and no study has tested centaury on its own for any effect on the urinary tract in people.

Mild indigestion and poor appetite are centaury’s officially recognized uses. EMA’s 2015 monograph accepts centaury tea, powder, tinctures, and extracts as a traditional herbal medicine for adults with “mild dyspeptic/gastrointestinal disorders” and “temporary loss of appetite,” a status that, as EMA explains, means effectiveness is plausible and use is documented for at least 30 years, including 15 in the European Union, but clinical trial evidence is insufficient. Commission E had earlier approved it for loss of appetite and peptic discomfort. Neither body had clinical trials to rely on: EMA’s assessors searched the medical databases and found no clinical studies of centaury alone, and the 2026 periodic review of ten years of newer literature found no relevant new data. The practical case therefore rests on the idea that bitters taken before a meal stimulate digestive secretions, and on generations of use as a single tea or in stomach blends in Germany, Austria, Poland, the Czech Republic, and elsewhere. Centaury sits in the same tradition as gentian and dandelion, and, as with them, nobody has measured in a trial how much it helps.

The most rigorous study involving centaury is a trial of the combination Canephron N, also called BNO 1045, for acute bladder infections. Wagenlehner and colleagues (Urologia Internationalis 2018) randomized 659 women aged 18 to 70 with uncomplicated cystitis at 51 centers in Germany, Ukraine, and Poland to Canephron N, two tablets three times a day for seven days, or a single 3 g dose of the antibiotic fosfomycin, with dummy medicines so that neither women nor doctors knew who got what. The main outcome was whether women needed an additional antibiotic within 38 days. In the per-protocol analysis, 16.5% of the Canephron group and 10.2% of the fosfomycin group did, a difference of about 6 percentage points that stayed within the 15-point non-inferiority margin the investigators had set; they acknowledged choosing it instead of the more usual 10 points. Symptoms improved faster with fosfomycin by day 4 but were similar by day 8, bacteria cleared from the urine better with fosfomycin, and five women on Canephron N developed pyelonephritis (kidney infection) against one on fosfomycin, a difference that was not statistically significant. Bionorica, the manufacturer, sponsored the trial, and some authors were its employees.

Smaller trials have tested the same combination for preventing infections. In an open-label Ukrainian trial, Sabadash and Shulyak (Clinical Phytoscience 2017) gave 90 women with recurrent E. coli cystitis a week of the antibiotic ofloxacin, and half of them also took Canephron N for three months; recurrences were lower in the herbal group at 6 months (8.9% versus 17.8%) and at 12 months (15.5% versus 35.5%), though neither patients nor doctors were blinded. After surgery for stress incontinence, 562 women took either three days of ciprofloxacin or three weeks of Canephron N liquid, and urinary infections over the next six months were similar, 13.6% versus 11.0% (Rechberger and colleagues, Journal of Clinical Medicine 2020); a 125-woman trial against fosfomycin after urogynecological surgery also found no significant difference (Wawrysiuk and colleagues, Pathogens 2022). A German prescription database study linked Canephron with fewer later recurrences than antibiotics, but it was retrospective and some authors worked for the manufacturer (Höller and colleagues, Antibiotics 2021). A 2026 meta-analysis of 12 studies with 3,821 patients called Canephron N an effective and safe alternative to antibiotics, but heterogeneity was high for its bacteriuria results, and its headline recurrence figures come from the Ukrainian trial in which every woman also received an antibiotic (Ak and colleagues, Neurourology and Urodynamics 2026).

Guidelines treat the combination cautiously. The EAU’s 2026 guidelines on urological infections cite the fosfomycin trial and make a weak recommendation that patients may be advised about a centaury, lovage, and rosemary combination, or a separate xyloglucan, hibiscus, and propolis product, to reduce repeat cystitis and antibiotic use. Fosfomycin, pivmecillinam, nitrofurantoin, and nitroxoline remain the strongly recommended first-line treatments. The EAU also strongly recommends telling women about antibiotic-sparing approaches and, where non-antibiotic treatment is chosen, using it in patients who are not elderly through shared decision-making. The trade-off is real. An individual-patient meta-analysis of 3,524 women in eight trials of non-antibiotic strategies, including analgesics, herbal products, and delayed prescriptions, found that they cut overall antibiotic use by 63% but tripled the odds of incomplete recovery and raised the odds of pyelonephritis more than fivefold (Kaußner and colleagues, Clinical Microbiology and Infection 2022). None of this applies to centaury on its own: the trials cannot separate the three herbs, and no study has tested centaury tea for bladder symptoms.

Centaury has many other folk uses that lack clinical support. EMA records historical use for fevers, painful periods, diabetes, snakebite, malaria, and wounds, and found that its use on the skin for inflammation and wounds did not meet the requirements for a monograph. El Menyiy and colleagues (Journal of Ethnopharmacology 2021) reviewed its traditional use in Morocco, Algeria, Italy, Spain, Portugal, and the Balkans for conditions including diabetes, fever, urinary infections, and digestive complaints, and called for further toxicology and pharmacokinetic studies. Rodent studies of blood sugar are interesting, but they have not been tested in people, so centaury should not be used to manage diabetes. As a bitter flavoring, centaury is better documented in drinks than in medicine: it is permitted in US alcoholic beverages and listed among vermouth herbs. For a herb with such a long history, the honest summary is that its digestive use is traditional, its urinary reputation rests on a three-herb product, and everything else is laboratory and animal work.

EMA’s monograph sets out the traditional preparations and single doses for adults and older people. For tea, 1 to 4 g of cut, dried herb is steeped in 200 ml (about a cup) of boiling water, up to four times a day. Powdered herb is taken at 0.25 to 2 g up to three times a day. A liquid extract made with 25% ethanol in a 1:1 herb-to-extract ratio is taken at 2 to 4 ml, and a tincture made with 70% ethanol at a 1:5 ratio at 1.5 to 5 g, each up to three times a day. A soft extract made with water, where 10 parts of herb yield 1 part of extract, is taken at 0.2 g per dose, 1 to 2 g a day. Commission E’s figure was about 6 g of herb a day, or 1 to 2 g of extract. EMA advises seeing a doctor if symptoms persist beyond two weeks or get worse, does not recommend any of these preparations under 18, and requires alcohol labeling on tinctures and ethanol-based extracts. The herb must meet the European Pharmacopoeia monograph, which uses swertiamarin as its identity marker.

In practice, centaury tea is intensely bitter, and that is the point. Grieve described an infusion of 1 ounce of herb to a pint of boiling water, taken by the wineglassful three or four times a day, half an hour before meals, for dyspepsia. Older handbooks summarized by EMA give single doses of about 1.5 to 3 g, and Bisset (1994) equated a teaspoon of herb to about 1.8 g. Registered products are usually simple teas: an Austrian single-herb tea contained 1.4 g per filter bag, taken three or four times daily, and two Polish teas were labeled for 1.5 to 2 g per cup. Germany reported no authorized single-herb centaury medicines in 2014, but 191 herbal teas containing it. Freshness affects quality. Aberham and colleagues (cited by EMA) found that swertiamarin stayed nearly unchanged at room temperature, while gentiopicroside and sweroside began to break down after six months of storage. Because the plant can accumulate cadmium and other metals near industry, products from suppliers who test for contaminants are preferable to herb gathered near roads or factories.

Centaury also appears in combination products. Canephron N coated tablets contain 18 mg each of powdered centaury herb, lovage root, and rosemary leaf, and were taken two at a time, three times daily, in the trials; liquid versions contain extracts of the same three herbs, and the incontinence-surgery trial used 5 ml three times a day. EMA’s table of marketed products shows these combinations registered in Bulgaria, Estonia, and other EU states as traditional medicines for supportive treatment of mild urinary tract inflammation and prevention of renal gravel (tiny kidney stones), so the approved use and age limits vary by country and label. Centaury also appears in multi-herb stomach teas, such as a Czech blend sold since 1971, and in an Estonian tonic solution containing more than 25 herbs. In the United States, federal food rules list centaury, under the name Centaurium umbellatum, among natural flavorings permitted only in alcoholic beverages. Anyone using a combination product alongside centaury tea or bitters should check the labels so as not to double up.