Blessed thistle has a long history of use in European herbal medicine. All parts of the above-ground plant are used medicinally. The herb was used primarily for digestive problems, including heartburn, gastritis, burping, constipation, and flatulence. Blessed thistle was also used for liver and gallbladder diseases. Blessed thistle is also a component of the famous herbal combination therapy Essiac, widely used (though without scientific support) as a treatment for cancer.
Blessed thistle contains the bitter constituent cnicin. Bitter substances are widely believed to promote appetite, though this has not been proven.
Cnicin does appear to have antimicrobial properties, killing bacteria and fungi in the test tube.1,2 These findings do not, however, indicate that blessed thistle can be used as an oral antibiotic. Antibiotics are substances that can be taken into the body at high enough doses to kill microbes throughout the system. In contrast, blessed thistle extracts, like those of many plants, appear to have antiseptic properties, meaning that they kill microbes on direct contact.
A typical dose of blessed thistle is 2 grams two or three times daily.
Although comprehensive safety studies have not been performed, blessed thistle is believed to be safe. However, cross-reactions are possible among people allergic to plants in the daisy family.
Safety in young children, pregnant or nursing women, or people with severe liver or kidney disease has not been established.
1. Bruno M, Rosselli S, Maggio A, et al. Antibacterial evaluation of cnicin and some natural and semisynthetic analogues. Planta Med. 2003;69:277–81.
2. Barrero AF, Oltra JE, Alvarez M, et al. New sources and antifungal activity of sesquiterpene lactones. Fitoterapia. 2000;71:60–4.
Last reviewed December 2015 by EBSCO CAM Review Board Last Updated: 12/15/2015