Blessed thistle, which is native to Europe and Asia, is now cultivated in many areas of the world, including the United States. The leaves, stems, and flowers are all used in herbal preparations. An annual herb, the blessed thistle stem grows to about 2 feet tall. The lance-shaped leaves have a spiny edge and may be either lobed or cleft (deeply cut). The plant produces numerous flowers during May through August that are arranged in a head at the tip of a branch or stem.

The active compounds within blessed thistle include sesquiterpene lactones, which provide the main beneficial effects of this herb. The bitterness of these compounds stimulates digestive activity, including the flow of saliva and secretion of gastric juice. This leads to improved appetite and digestion. There also is some evidence that blessed thistle has anti-inflammatory properties. Folk medicine utilized blessed thistle tea for digestive problems, including gas, constipation, and stomach upset. The herb also was used for treating liver and gallbladder diseases, much like its well-known relative, milk thistle.

Monks once grew blessed thistle as a cure for small pox. Early herbalists believed that this herb was a cure-all. They noted that the plant could prevent and cure headache, provoke sweat, help memory, strengthen the heart and stomach, and cure external problems such as festering sores, boils, and the itch. Nineteenth century herbalists prescribed blessed thistle as an infusion, or tea, made from the plant tops for the treatment of fevers along with liver and respiratory ailments. Blessed thistle may be useful in the treatment of indigestion and heartburn as well as poor appetite.

In herbal medicine today, blessed thistle is sometimes suggested as an herbal treatment for cancer, infections, heart and liver ailments, and fevers. Some believe drinking a cup of thistle tea twice a day will cure chronic headaches. It also is used for stomach and digestive problems, intestinal gas, constipation, and liver troubles. Many have found it to be effective for treating dropsy, strengthening the heart, and improving the function of the liver, lungs, and kidneys. It is claimed that the warm tea, given to new mothers, will help to produce a good supply of milk. Blessed thistle also is said to be a good tonic for girls entering womanhood.

Blessed thistle is considered relatively safe and free from side-effects except for those with allergies to plants in the daisy family.