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Blessed Thistle

Scientific Name(s): Cnicus benedictus
Common Name(s): Cardin, Carduus benedictus, Holy thistle, Spotted thistle, St. Benedict's thistle

Medically reviewed by Last updated on Aug 15, 2022.

Clinical Overview


Blessed thistle has been traditionally used to stimulate secretion of gastric juices and saliva, to increase appetite and facilitate digestion, and to stimulate the flow of bile. It is a common ingredient in combination formulas for gastric health. Anti-inflammatory, antimicrobial, and cytotoxic activities have been reported and thought to be due to the chemical constituent cnicin. However, there are no clinical trials to support these potential uses.


No clinical studies exist to provide dosing recommendations for blessed thistle. Doses of 4 to 6 g daily have been traditionally used.


Blessed thistle is contraindicated in patients with gastric ulcers or other inflammatory bowel conditions, such as Crohn disease.


Avoid use. Blessed thistle should not be used in pregnancy. Information regarding safety and efficacy in lactation is lacking.


None well documented.

Adverse Reactions

Allergy and cross sensitization have been reported with other members of the Asteraceae family. Stimulation of gastric acid secretion has been reported. Emesis is likely with high dosages.


Clinical information is limited. Emesis is likely with high dosages (5 g or more).

Scientific Family

  • Asteraceae (daisy)


Blessed thistle is native to southern Europe, western Asia, and North Africa, and has been naturalized throughout the United States and Europe. It is considered a noxious weed and grows mostly in stony, uncultivated areas. It is an annual, growing about 0.7 m in height with leathery, hairy leaves 30 cm long and 8 cm wide. The entire plant is covered with down and bears pale yellow flowers in dense, prickly flower heads. Blessed thistle should not be confused with Silybum marianum, which is commonly referred to as "milk thistle."Duke 2002, Khan 2009, Ulbricht 2008, USDA 2016 Synonyms are Centaurea benedicta and Cirsium pugnax.


The plant was widely cultivated during the Middle Ages in Europe and was used in many herbal formulations of the period.Blumenthal 2000 Its medicinal use as a healing herb was mentioned by Shakespeare in his play Much Ado About Nothing.Shakespeare 1914 It was thought to be useful against the bubonic plague; however, its main uses were for treatment of digestive complaints, gout, fever, and headache.Duke 2002, Khan 2009 Blessed thistle was also recommended as an emmenagogue and galactogogue, and for the treatment of intestinal worms.Duke 2002, Khan 2009 The plant's dried leaves, stems, and flowers have been used medicinally. Blessed thistle, used in flavoring Bénédictine liqueur, has generally recognized as safe (GRAS) status as a flavoring agent. It is available as a single herb and in homeopathic preparations. Blessed thistle is approved by the German Commission E for treatment of dyspepsia and loss of appetite, and is a minor component of a multiherb cancer remedy formulation.Blumenthal 2000


The most prominent constituent of blessed thistle is the bitter sesquiterpene lactone ester cnicin. The leaves and plant parts contain tannins, sesquiterpenes, a high mineral content (primarily potassium, manganese, magnesium, and calcium), phytosterols, triterpenoids, and small amounts of volatile oil.Blumenthal 2000, Duke 1992, Jaiswal 2011, Khan 2009 Linoleic and oleic acid have been identified in the seed.Duke 1992

Uses and Pharmacology

Animal data

Limited studies suggest cytotoxicDuke 2002, Erel 2011, Vanhaelen-Fastrè 1972, Vanhaelen-Fastré 1978 and antimicrobial activityBroekaert 1993, Bruno 2003, Duke 2002, Panagouleas 2003 of extracts of the plant and of the chemical constituent cnicin. Cnicin has been shown to have anti-inflammatory properties in vitro and in rat paw edema tests, with similar efficacy to indomethacin.Duke 2002, Erel 2011 Inhibition of acetylcholinesterase and antioxidant activity has also been demonstrated by an ethanol extract of the plant.Paun 2015

Clinical data

Use of blessed thistle is largely based on the ability of the bitter principle cnicin to stimulate secretion of gastric juices and saliva, and potentially bile; however, research reveals no clinical data regarding use of this plant for any indication.


No clinical studies exist to provide dosing recommendations for blessed thistle. Doses of 4 to 6 g daily have been traditionally used. The leaves (1.5 to 2 teaspoons per cup of water) and dried flowering shoots (1.5 to 3 g 3 times/day) have also been used.Blumenthal 2000, Duke 2002

Pregnancy / Lactation

Avoid use. Blessed thistle has been traditionally used as an emmenagogue and should not be used in pregnancy. Although traditionally used to promote lactation, information regarding safety and efficacy in lactation is lacking.Blumenthal 2000, Duke 2002, Khan 2009, Ulbricht 2008 Blessed thistle was identified as one of the 4 most common herbs used by certified or licensed midwives for increasing lactation based on state-wide surveys in California, Texas, and North Carolina.Dennehy 2010


None well documented.

Adverse Reactions

Allergy and hypersensitivity to blessed thistle have been reported.Ulbricht 2008 Use caution in people sensitive to other asteraceous plants. Blessed thistle extract was found to be strongly sensitizing in a study of 12 species in the Asteraceae family.Blumenthal 2000, Duke 2002, Ulbricht 2008

At high doses (5 to 6 g), blessed thistle is a known emetic.Blumenthal 2000, Duke 2002, Ulbricht 2008 Avoid use in persons with gastric ulcers, as stimulation of gastric acid secretion has been reported.Blumenthal 2000, Duke 2002, Ulbricht 2008


Clinical information is limited. The oral, median lethal dose of cnicin in mice was 1.6 to 3.2 mmol/kg.Khan 2009

Index Terms

  • Centaurea benedicta
  • Cirsium pugnax



This information relates to an herbal, vitamin, mineral or other dietary supplement. This product has not been reviewed by the FDA to determine whether it is safe or effective and is not subject to the quality standards and safety information collection standards that are applicable to most prescription drugs. This information should not be used to decide whether or not to take this product. This information does not endorse this product as safe, effective, or approved for treating any patient or health condition. This is only a brief summary of general information about this product. It does NOT include all information about the possible uses, directions, warnings, precautions, interactions, adverse effects, or risks that may apply to this product. This information is not specific medical advice and does not replace information you receive from your health care provider. You should talk with your health care provider for complete information about the risks and benefits of using this product.

This product may adversely interact with certain health and medical conditions, other prescription and over-the-counter drugs, foods, or other dietary supplements. This product may be unsafe when used before surgery or other medical procedures. It is important to fully inform your doctor about the herbal, vitamins, mineral or any other supplements you are taking before any kind of surgery or medical procedure. With the exception of certain products that are generally recognized as safe in normal quantities, including use of folic acid and prenatal vitamins during pregnancy, this product has not been sufficiently studied to determine whether it is safe to use during pregnancy or nursing or by persons younger than 2 years of age.

Blumenthal M, Goldberg A, Brinckmann J, eds. Herbal Medicine: Expanded Commission E Monographs. Newton, MA: Integrative Medicine Communications; 2000.
Broekaert WF, Cammue BPA, Osborn RW, et al, inventors. A family of fungicidal and bactericidal proteins from plant seeds. WO Patent No. 9305153. March 1993.
Bruno M, Rosselli S, Maggio A, Raccuglia RA, Napolitano F, Senatore F. Antibacterial evaluation of cnicin and some natural and semisynthetic analogues. Planta Med. 2003;69(3):277-281.12677537
Cnicus benedictus. USDA, NRCS. 2016. The PLANTS Database (, September 2016). National Plant Data Team, Greensboro, NC 27401-4901 USA. Accessed September 29, 2016.
Dennehy C, Tsourounis C, Bui L, King TL. The use of herbs by California midwives. J Obstet Gynecol Neonatal Nurs. 2010;39(6):684-693.21044150
Duke J, Bogenschutz-Godwin M, duCellier J, Duke P. Handbook of medicinal herbs. 2nd ed. Boca Raton, FL: CRC Press; 2002.
Duke J. Handbook of Biologically Active Phytochemicals and Their Activities. Boca Raton, FL: CRC Press, Inc; 1992.
Erel SB, Karaalp C, Bedir E, et al. Secondary metabolites of Centaurea calolepis and evaluation of cnicin for anti-inflammatory, antioxidant, and cytotoxic activities. Pharm Biol. 2011;49(8):840-849.21612369
Jaiswal R, Kiprotich J, Kuhnert N. Determination of the hydroxycinnamate profile of 12 members of the Asteraceae family. Phytochemistry. 2011;72(8):781-790.21453943
Khan I, Abourashed E. Leung's Encyclopedia of Common Natural Ingredients Used in Food, Drugs, and Cosmetics. 3rd ed. Hoboken, NJ: Wiley; 2009.
Panagouleas C, Skaltsa H, Lazari D, Skaltsounis AL, Sokovic M. Antifungal activity of secondary metabolites of Centaurea raphanina ssp. mixta, growing wild in Greece. Pharm Bio. 2003;41(4):266-270.
Paun G, Neagu E, Albu C, Radu GL. Inhibitory potential of some Romanian medicinal plants against enzymes linked to neurodegenerative diseases and their antioxidant activity. Pharmacogn Mag. 2015;11(suppl 1):S110-S116.26109755
Shakespeare W. Much Ado about Nothing. 3.4. London: Oxford University Press; 1914.
Ulbricht C, Basch E, Dacey C, et al. An evidence-based systematic review of blessed thistle (Cnicus benedictus) by the Natural Standard Research Collaboration. J Diet Suppl. 2008;5(4):422-437.
Vanhaelen-Fastrè R. Antibiotic and cytotoxic activity of cnicin isolated from Cnicus benedictus L. [in French]. JPharm Belg. 1972;27(6):683-688.4665015
Vanhaelen-Fastré R, Vanhaelen M. Antibiotic and cytotoxic activity of cnicin and of its hydrolysis products. Chemical structure - biological activity relationship (author’s transl) [in French]. Planta Med. 1976;29(2):179-189.948519

Further information

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