Blessed thistle contains lignans, essential oil, tannins, and the minerals calcium, potassium, iron, magnesium and manganese. The main bitter substance is cnicin present in a concentration of 0.2 to 0.7 percent.
In Greek folk medicine the herb was used to treat malaria, and the common belief was it could cure epidemic diseases such as measles, chickenpox, smallpox, and plague.
The herb is often used in the form of herbal teas as an herbal remedy for loss of appetite, indigestion (which is not related to ulcers), respiratory ailments, intestinal worms, constipation, flatulence, colic, anorexia and ailments associated with poor liver function like headache, fatigue and irritability.
The bitter substance found in blessed thistle is what makes the herb stimulate the appetite and enhance digestion through increased secretion of juices from the salivary glands, stomach, pancreas, gallbladder, and bowels.
The astringent (constricting) properties of the plant makes it a good remedy for treating diarrhea. When used to treat diarrhea, it is often combined with other herbs with high tannin content like agrimony (Agrimonia eupatoria), meadowsweet (Filipendula ulmaria) and tormentil (Potentilla erecta).
Blessed thistle has antibiotic properties due to the substance cnicin, the essential oil and the polyacetylene found in the plant.
It may be used to help stimulate the immune system
The herb also has diuretic properties that may prove useful for high fever and feverish conditions.
It has been used against Staphylococcus aureus and Escherichia coli due to the germicidal properties of the plant. The herb also contains substances that have been reported to prevent HIV.
Blessed thistle has been used traditionally to treat some symptoms of menopause, to relieve painful menstruation, menstrual cramps and menstrual headaches and also for increasing milk production in lactating mothers.
It is thought to increase blood circulation to the brain and is used traditionally to improve memory and concentration and to relieve headaches (especially if related to poor liver function) and depression.