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Blessed Thistle

What is it?

Blessed thistle (Cnicus benedictus) is a flowering plant with sharp prickles on the stems and leaves. It's native to the Mediterranean region.

Blessed thistle contains chemicals called tannins, which might help with diarrhea, cough, and swelling.

People use blessed thistle for indigestion, infections, wounds, and many other conditions, but there is no good scientific evidence to support these uses.

Don't confuse blessed thistle with milk thistle. These are not the same.

How effective is it?

There is interest in using blessed thistle for a number of purposes, but there isn't enough reliable information to say whether it might be helpful.

Is it safe?

When taken by mouth: Blessed thistle is commonly consumed in foods. There isn't enough reliable information to know if blessed thistle is safe to use as medicine or what the side effects might be. In doses greater than 5 grams per cup of tea, blessed thistle might cause stomach upset and vomiting.

When applied to the skin: There isn't enough reliable information to know if blessed thistle is safe or what the side effects might be. Blessed thistle might cause an allergic reaction in some people.

Special precautions & warnings:

Pregnancy: Blessed thistle is likely unsafe to use while pregnant. Don't use it.

Breast-feeding: There isn't enough reliable information to know if blessed thistle is safe to use when breast-feeding. Stay on the safe side and avoid use.

Intestinal problems, such as infections, Crohn's disease, and other inflammatory conditions: Don't take blessed thistle if you have any of these conditions. It might irritate the stomach and intestines.

Allergy to ragweed and related plants: Blessed thistle might cause an allergic reaction in people who are sensitive to the Asteraceae/Compositae family. Members of this family include ragweed, chrysanthemums, marigolds, daisies, and many others.

Are there interactions with medications?

Be watchful with this combination.
Antacids are used to decrease stomach acid. Blessed thistle can increase stomach acid. Taking blessed thistle might decrease the effects of antacids.
Medications that decrease stomach acid (H2-blockers)
H2-blockers are used to decrease stomach acid. Blessed thistle can increase stomach acid. Taking blessed thistle might decrease the effects of H2-blockers.

Some common H2-blockers include cimetidine (Tagamet), ranitidine (Zantac), and famotidine (Pepcid).
Medications that decrease stomach acid (Proton pump inhibitors)
Proton pump inhibitors are used to decrease stomach acid. Blessed thistle can increase stomach acid. Taking blessed thistle might decrease the effects of proton pump inhibitors.

Some common proton pump inhibitors include omeprazole (Prilosec), lansoprazole (Prevacid), rabeprazole (Aciphex), pantoprazole (Protonix), and esomeprazole (Nexium).

Are there interactions with herbs and supplements?

There are no known interactions with herbs and supplements.

Are there interactions with foods?

There are no known interactions with foods.

How is it typically used?

Traditionally, blessed thistle has most often been used by adults as a tea. It's also used as a liquid extract. Speak with a healthcare provider to find out what type of product and dose might be best for a specific condition.

Other names

Carbenia Benedicta, Cardo Bendito, Cardo Santo, Carduus, Carduus Benedictus, Chardon Béni, Chardon Bénit, Chardon Marbré, Cnici Benedicti Herba, Cnicus, Cnicus benedictus, Holy Thistle, Safran Sauvage, Spotted Thistle, St. Benedict Thistle.


To learn more about how this article was written, please see the Natural Medicines Comprehensive Database methodology.


  1. Ahmadimoghaddam D, Sadeghian R, Ranjbar A, Izadidastenaei Z, Mohammadi S. Antinociceptive activity of Cnicus benedictus L. leaf extract: a mechanistic evaluation. Res Pharm Sci 2020;15:463-472. View abstract.
  2. Paun G, Neagu E, Albu C, et al. Inhibitory potential of some Romanian medicinal plants against enzymes linked to neurodegenerative diseases and their antioxidant activity. Pharmacogn Mag. 2015;11(Suppl 1):S110-6. View abstract.
  3. Duke JA. Green Pharmacy. Emmaus, PA: Rodale Press;1997:507.
  4. Recio M, Rios J, and Villar A. Antimicrobial activity of selected plants employed in the Spanish Mediterranean area. Part II. Phytother Res 1989;3:77-80.
  5. Perez C and Anesini C. Inhibition of Pseudomonas aeruginosa by Argentinean medicinal plants. Fitoterapia 1994;65:169-172.
  6. Vanhaelen M and Vanhaelen-Fastre R. Lactonic lignans from Cnicus benedictus. Phytochemistry 1975;14:2709.
  7. Kataria H. Phytochemical investigation of medicinal plant Cnicus wallichii and Cnicus benedictus L. Asian J Chem 1995;7:227-228.
  8. Vanhaelen-Fastre R. [Polyacetylen compounds from Cnicus benedictus]. Planta Medica 1974;25:47-59.
  9. Pfeiffer K, Trumm S, Eich E, and et al. HIV-1 integrase as a target for anti-HIV drugs. Arch STD/HIV Res 1999;6:27-33.
  10. Ryu SY, Ahn JW, Kang YH, and et al. Antiproliferative effect of arctigenin and arctiin. Arch Pharm Res 1995;18:462-463.
  11. Cobb E. Antineoplastic agent from Cnicus benedictus. Patent Brit 1973;335:181.
  12. 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 Med 1976;29:179-189. View abstract.
  13. 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;60:1034-1035. View abstract.
  14. 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;39:86-95. View abstract.
  15. Nose, M., Fujimoto, T., Nishibe, S., and Ogihara, Y. Structural transformation of lignan compounds in rat gastrointestinal tract; II. Serum concentration of lignans and their metabolites. Planta Med 1993;59:131-134. View abstract.
  16. Hirano, T., Gotoh, M., and Oka, K. Natural flavonoids and lignans are potent cytostatic agents against human leukemic HL-60 cells. Life Sci 1994;55:1061-1069. View abstract.
  17. Perez, C. and Anesini, C. In vitro antibacterial activity of Argentine folk medicinal plants against Salmonella typhi. J Ethnopharmacol 1994;44:41-46. View abstract.
  18. Vanhaelen-Fastre, R. [Constitution and antibiotical properties of the essential oil of Cnicus benedictus (author's transl)]. Planta Med 1973;24:165-175. View abstract.
  19. Vanhaelen-Fastre, R. [Antibiotic and cytotoxic activity of cnicin isolated from Cnicus benedictus L]. J Pharm Belg. 1972;27:683-688. View abstract.
  20. Schneider, G. and Lachner, I. [Analysis and action of cnicin]. Planta Med 1987;53:247-251. View abstract.
  21. May, G. and Willuhn, G. [Antiviral effect of aqueous plant extracts in tissue culture]. Arzneimittelforschung 1978;28:1-7. View abstract.
  22. Mascolo N, Autore G, Capassa F, et al. Biological screening of Italian medicinal plants for anti-inflammatory activity. Phytother Res 1987:28-31.
  23. Electronic Code of Federal Regulations. Title 21. Part 182 -- Substances Generally Recognized As Safe. Available at:
  24. Brinker F. Herb Contraindications and Drug Interactions. 2nd ed. Sandy, OR: Eclectic Medical Publications, 1998.
  25. McGuffin M, Hobbs C, Upton R, Goldberg A, eds. American Herbal Products Association's Botanical Safety Handbook. Boca Raton, FL: CRC Press, LLC 1997.
  26. Leung AY, Foster S. Encyclopedia of Common Natural Ingredients Used in Food, Drugs and Cosmetics. 2nd ed. New York, NY: John Wiley & Sons, 1996.
  27. Newall CA, Anderson LA, Philpson JD. Herbal Medicine: A Guide for Healthcare Professionals. London, UK: The Pharmaceutical Press, 1996.
Last reviewed - 08/07/2023