Centaurea benedicta (1,2), Carduus benedictus (1,3,4), Carbenia benedicta Family:
Asteraceae (Compositeae) Common names:
Blessed thistle, Holy thistle (1,2,3,5,6)

Part(s) used:
Whole herb (Cnici benedicti herba) - leaves and flowering tops (1,2,3,4,5,6)


Blessed thistle is an erect annual with a slender red spiny stem (growing up to 0.7m). The leaves are amplexicaul (clasping the stem), somewhat decurrent, leathery, with the irregular teeth of the wavy margin ending in spines. The upper leaves are sessile; the lower ones petioled. The flower heads are yellow and surrounded by spine-tipped bracts. The whole plant, leaves, stalks and also the flowerheads, are covered with a thin down. Blessed thistle originated in the Mediterranean region. It has been introduced in most parts of Europe, Asia, South Africa and Central and South America. This plant flourishes on dry stony ground and in open areas. It grows more compactly in some soils than in others. The commercial product comes from eastern and southern Europe. The leaves and flowering tops are collected in summer (1,2,3,4).


Historically, blessed thistle was regarded as a cure for the bubonic plague (3,4,7). Grieve states that blessed thistle is mentioned in all treatises on the Plague, �and especially by Thomas Brasbridge, who in 1578 published his �Poore Man�s Jewell, that is to say, Treatise on the Pestilence, unto which is annexed a declaration of the vertues of the Hearbes Carduus Benedictus and Angelica� (3). A. Vogel suggests that the name benedictus may refer to the Benedictine monks who used blessed thistle during the Middle Ages to treat the Plague. �In the 17th century, Matthiolus wrote of the blessed thistle: �...there is hardly a better medication for cancer and other rotting damage.� Cancerous growths on the outer body were washed with �cardobenedictine� water and sprinkled with the crushed herb� (8). Traditionally, blessed thistle has been used to treat anorexia, dyspepsia (1,2,3,5,6,7), flatulence, indigestion (3,5,7), diarrhoea (5,7), dysmenorrhoea (7), migraine (3,5), to stimulate lactation (3,5,7) and for wound healing (2,4,7). It has also been used as an abortifacient (7).

Major Active Constituents

The biological activity of blessed thistle is ascribed mainly to the principal bitter constituents - sesquiterpene lactone glycosides of the germacrane type (2,4,5,7). The main constituent is cnicin (0.2-0.7%) (2,4,6,7). Other constituents include polyacetylen (9), and absinthin (10); triterpenoids such as a-amyrenone, a-amyrin acetate, a-amyrine, and multiflorenol acetate (10; 11); lignans such as trachelogenin, arctigenin (2,7), and nortracheloside (12); flavonoids; polyacetylenes; tannins (8%); and essential/volatile oil (0.3%) with p-cymene, fenchon, citral and cinnamaldehyde (2,4,7). Salonitenolide has also been found to be present (9). Lignan lactones such as trachelogenin and arctigenin may contribute to the bitter characteristics of blessed thistle (2,7).


Bitter tonic, appetite stimulant (1,2,3,4,5,7), diaphoretic, emmenagogue (1,3,5,7), galactagogue (3,5), emetic at high doses (1,3,4,5), anti-microbial/antibiotic (4,5,13,14,15), anti-inflammatory (2,16,17), anti-proliferative (18,19,20,21,22,23,24), antitumour/antineoplastic (2), wound healing (2,4,7).


Anti-microbial effects
The sesquiterpene lactone cnicin has a structure allowing it to form covalent bonds with proteins. This is due to the a-methylen-?-lactone structures of bitter terpenoid lactones, which are known to have antibacterial properties (2). In vitro studies observing the effects of cnicin and the essential oil of blessed thistle against Bacillus subtilis, Brucella species, Escherichia coli, Proteus species, Pseudomonas aeruginosa, Staphyloccoccus aureus and Streptococcus faecalis show that these constituents possess antibacterial activity against these strains, suggesting a broad spectrum of anti-microbial activity (13,14,15). There have been studies investigating several lignans in Cnicus benedictus as possible anti-HIV and anti-cancer agents (20,21,25,26) but so far the evidence remains unclear.

Anti-inflammatory effects
Pharmacokinetic studies show that following oral ingestion of blessed thistle by rats, the lignans arctiin and tracheloside are metabolized to their genins, arctigenin and trachelogenin (16). Studies on rats indicate that these lignans appear to exert inhibitory effects on cyclic AMP, phosphodiesterase, and histamine release in mast cells (16). Cnicin has demonstrated mild anti-inflammatory effects in the standard rat paw model of inflammation (17). Platelet activating factor (PAF) antagonist activities have also been observed, as well as antagonist action against calcium ions (16).

Anti-proliferative effects
Studies investigating the antineoplastic and cytotoxic effect of constituents in blessed thistle have been done, investigating the effects against some tumour cell lines including leukemia (HL-60), hepatomas, and sarcomas. These studies indicate that the constituents cnicin and arctigenin exhibit anti-tumour activity via inhibition of cellular DNA, RNA or protein synthesis (15,18,19,20,21,22,23). Differentiation in mouse myeloid leukaemia cell lines has been observed due to arctigenin activity (24).

Clinical Outcome Studies

No results were found through Medline search.


Anorexia/loss of appetite, dyspepsia (1,2,3,5,6,7), minor digestive complaints (2,4), flatulence, indigestion, intermittent fevers (1,3,4,5,7), stimulation of lactation (3,5), applied topically for wounds and ulcers (2,4,7). Anecdotally, blessed thistle has also been recommended for cervical dysplasia (7), diarrhoea, haemorrhage (5,7), and dysmenorrhoea (7).

Contra-indications and Cautions

Blessed thistle should be avoided during pregnancy due to the potential emmenagogue and abortifacient properties (4,5,7). Although blessed thistle has traditionally been used to stimulate lactation, there is a paucity of safety information, so it is currently not recommended for this use (7).

Traditionally, blessed thistle is believed to increase GIT secretions (4,7) and should therefore be used with caution in cases of peptic ulcer (7).

Allergy/hypersensitivity has been reported, and there is a potential for allergic cross-reactivity reactions from other plants within the Asteraceae family such as echinacea and mugwort. This is believed to be due to the sesquiterpene lactones. Blessed thistle may cause contact dermatitis in some individuals.

In large doses (>5g per cup of tea), blessed thistle may cause vomiting (1,3,4,5,7).


Recommended doses are based on historical practice.

Adult dose:
Tincture: 7.5-10mL (1.5g/L blessed thistle) tds has been used (7).
Liquid extract (1:1g/mL in 25% alcohol): 1.5-3.0mL tds has been used (5,7).
Infusion: 1.5-2g of blessed thistle in 150mL water tds has been used (7). Infusion should be drunk cold as a tonic, and warm as a diaphoretic and emmenagogue (1).
Tea: 1.5-3g of dried blessed thistle flowering tops steeped in boiling water and taken as tea tds, or: 1-3 tsp of dried blessed thistle herb in one cup boiling water for 5-15mins; 1 cup may be taken tds (5,7), recommended by some to be used 30mins - 1hour before meals (2,7). Bitter in taste (7).

Large doses are emetic (1,3,4,5).

Poultice: Flowerheads (5).

Safety and efficacy data for children is lacking, and blessed thistle is generally not recommended in infancy or early childhood (7).


1. Felter HW, Lloyd JU. 1898-1900. King�s American dispensatory. Vol. I. 18th ed. Sandy, Oregon: Eclectic Medical Publications.

2. van Wyk B-E, Wink M. 2004. Medicinal Plants of the World. Pretoria: Briza.

3. Grieve M. 1973. A Modern Herbal. Surrey: Merchant.

4. Chevalier A. 2000. Encyclopedia of Herbal Medicine. 2nd ed. Great Britain: Dorling Kindersley.

5. Bartram T. 1998. Bartram�s Encyclopedia of Herbal Medicine. London: Robinson.

6. Blumenthal M (ed.) 1998. The German Commission E monographs. Austin,Texas: American Botanical Council.

7. Natural Standard Monograph. 2008. Natural Standard Inc. Cambridge, MA, USA. Accessed 17 September 2008. <>.

8. Cnicus benedictus L. Blessed Thistle. A. Vogel. 2005. Bioforce CA. Accessed 21 September 2008. <>.

9. Vanhaelen-Fastre R. [Polyacetylen compounds from Cnicus benedictus]. Planta Medica 1974;25:47-59.

10. Kataria H. Phytochemical investigation of medicinal plant Cnicus wallichii and Cnicus benedictus L. Asian J Chem 1995;7:227-228.

11. Ulbelen A and Berkan T. Triterpenic and steroidal compounds of Cnicus benedictus. Planta Medica 1977;31:375-377.

12. Vanhaelen M and Vanhaelen-Fastre R. Lactonic lignans from Cnicus benedictus. Phytochemistry 1975;14:2709.

13. Vanhaelen-Fastre, R. [Antibiotic and cytotoxic activity of cnicin isolated from Cnicus benedictus L]. J Pharm Belg. 1972;27(6):683-688.

14. Vanhaelen-Fastre, R. [Constitution and antibiotical properties of the essential oil of Cnicus benedictus (author's transl)]. Planta Medica 1973;24(2):165-175.

15. Vanhaelen-Fastre, R. and Vanhaelen, M. [Antibiotic and cytotoxic activity of cnicin and of its hydrolysis products. Chemical structure - biological activity relationship (author's transl)]. Planta Medic 1976;29(2):179-189.

16. Nose, M., Fujimoto, T., Nishibe, S., and Ogihara, Y. Structural transformation of lignan compounds in rat gastroin-testinal tract; II. Serum concentration of lignans and their metabolites. Planta Medica 1993;59(2):131-134.

17. Mascolo N, Autore G, Caspasso F, and et al. Biological screening of Italian medicinal plants for antiinflammatory activity. Phytother Res 1987;1:28-31.

18. Barrero, A. F., Oltra, J. E., Morales, V., Alvarez, M., and Rodriguez-Garcia, I. Biomimetic cyclization of cnicin to malacitanolide, a cytotoxic eudesmanolide from Centaurea malacitana. J Nat Prod. 1997;60(10):1034-1035.

19. Cobb E. Antineoplastic agent from Cnicus benedictus. Patent Brit 1973;335:181.

20. Eich, E., Pertz, H., Kaloga, M., Schulz, J., Fesen, M. R., Mazumder, A., and Pommier, Y. (-)-Arctigenin as a lead structure for inhibitors of human immunodeficiency virus type-1 integrase. J Med Chem 1-5-1996;39(1):86-95.

21. Hirano, T., Gotoh, M., and Oka, K. Natural flavonoids and lignans are potent cytostatic agents against human leu-kemic HL-60 cells. Life Sci 1994;55(13):1061-1069.

22. Moritani S, Nomura M, Takeda Y, and et al. Cytotoxic components of Bardanae Fructus (Goboshi). Biol Pharm Bull 1996;19:1515-1517.

23. Ryu SY, Ahn JW, Kang YH, and et al. Antiproliferative effect of arctigenin and arctiin. Arch Pharm Res 1995;18(6):462-463.

24. Umehara K, Sugawa A, Kuroyanagi M, and et al. Studies on the differentiation-inducers from Arctium fructus. Chem Pharm Bull 1993;41:1774-1779.

25. Maeda Y and Mitsuya H. Antiretroviral chemotherapy against AIDS. Med Biol Environ 1995;23:267-278.

26. Yang L, Lin S, Yang T, and et al. Synthesis of anti-HIV activity of dibenzylbutyrolactone lignans. Bioorg Med Chem Lett 1996;6(8):941-944.


This monograph was authored in 2008 by Sonia Hicks, a student in Southern Cross University�s Bachelor of Naturopathy programme, and edited by Nena Aleschewski BNat. While the author and editor have strived to cite published information accurately, Southern Cross University will not be re-sponsible for any inaccuracies that may have occurred.

This information is provided for educational purposes only and does not constitute medical advice. If you wish to use herbal medicine as part of your health care, seek the advice of an appropriately qualified practitioner.