Health Benefits of Blessed Thistle

Middle Ages Cure-All Used to Increase Breastmilk

Blessed thistle (Cnicus benedictus) is a plant native to the Mediterranean from southern France to Iran. It is recognized by its hairy, dandelion-like leaves and fuzzy, yellow blossoms.

Blessed thistle, also known as holy thistle, has been used since the Middle Ages to treat bubonic plague, promote digestive health and prevent infection. Today, blessed thistle is most commonly used to increase the production of breastmilk in nursing mothers.

Blessed thistle is typically prepared as a tea using the tops, leaves, and upper stems or sold as a supplement in capsule, tincture, or powdered forms. In addition to promoting lactation, blessed thistle is believed to stimulate appetite and treat diarrhea, indigestion, colds, and flu. Others apply blessed thistle directly to boils, abscesses, and other skin infections to speed healing.

Outside of its medicinal uses, blessed thistle is a key ingredient in the alcoholic liqueur Benedictine.

side effects of blessed thistle
Verywell / Brianna Gilmartin

Blessed thistle was so-named because of its use as a tonic among the Benedictine monks of the 14th century. Blessed thistle should not be confused with milk thistle (Silybum marianum), which is commonly used for liver disorders.

What Research Tells Us About Blessed Thistle

Blessed thistle is believed to stimulate lactation in nursing parents. It might be able to fight off bacterial infections in the body, and possibly even be an anti-carcinogen. More research will help confirm just how much this herb can really do.

The use of blessed thistle in folk medicine has been handed down from one generation to the next. In most cases, there is little clinical evidence to support its use. Although bitter, the plant is edible and rich in a compound known as cnicin, which is believed to have anti-inflammatory, antibacterial, and anti-cancer properties.

Here is what some of the current research says about blessed thistle:


Alternative practitioners will commonly prescribe blessed thistle as a galactagogue, which is something you take to stimulate lactation. Although it is believed to increase the hormones prolactin (which boosts the milk supply) and oxytocin (which enables to release of milk from the nipples), there is nothing in the current body of medical literature to suggest this actually occurs.

As 2016 review of studies from Tulane University didn't so much dismiss blessed thistle as a galactagogue. Rather, the researchers concluded that the available studies were poor and failed to meet the basic criteria of inclusion.

By contrast, milk thistle has been shown to be beneficial in promoting lactation in a number of smaller studies, including a 2008 trial from Italy in which the use of S. marianum increased breastmilk production in nursing mothers by 64.43% compared to 22.51% in the placebo group.

Further research is needed to determine whether these same properties can be attributed to milk thistle.

Bacterial Infection

There is little evidence that blessed thistle can prevent or avert the course of the common cold, flu, or other viral infections. On the hand, research suggests that the herb may help neutralize certain common bacteria, including Staphylococcus aureus.

According to a study published in the Journal of Medicinal Chemistry, the cnicin in blessed thistle binds to bacteria in a unique way, blocking the enzymes needed for bacterial replication. By doing, the bacteria are unable to reproduce and quickly die.

While it is unknown how potent this effect is, particularly when taken by mouth, the results lend further credence to the use of blessed thistle as a topical antibacterial. The same effect may be extended to common fungal infection as well.


Even less is known about cnicin's purported anti-tumor properties. Most of the research is limited to tests tube studies, some of which have shown that cnicin is not toxic to Mycobacterium tuberculosis (TB) or breast cancer cells. Much more research would be needed to see if these same effects can occur outside of the test tube.

Possible Side Effects

Blessed thistle is considered safe when used as a tea. However, even in its tea form, it can cause stomach upset, nausea, and vomiting if consumed in excess. The same applies to blessed thistle supplements and tinctures.

Blessed thistle should be avoided in people with inflammatory bowel diseases like Crohn's disease and ulcerative colitis. Doing so can lead to a rebound or worsening of symptoms.

Blessed thistle may cause allergy in some people, most commonly in those who are allergic to plants of the Asteraceae/Compositae family (including ragweed, chrysanthemums, marigolds, and daisies).

Blessed thistle also exerts a mild diuretic effect and should be used with caution if you are taking a pharmaceutic diuretic ("water pill") like Lasix (furosemide).

Since blessed thistle can increase stomach acid, it may interfere with antacids and other heartburn medications (including proton pump inhibitors and H2 blockers). To be safe, take blessed thistle four hours before or four hours after an antacid dose.

While blessed thistle is presumed to be safe for nursing mothers, it may stimulate uterine contractions and should be avoided during pregnancy. Do not use blessed thistle or any similar herbal product in children.

Dosage and Preparation

There are no guidelines directing the appropriate use of blessed thistle. Most supplements are offered in 300-milligram to 450-milligram formulations; thrice-daily doses are considered safe within this range. Doses over 5 grams (5,000 milligrams) per day are associated with an increased risk of side effects.

Blessed thistle tea can be made by steeping 1 to 3 teaspoons of the dried herb in one cup of hot water for 10 minutes. Proponents believe that taking blessed thistle with fenugreek can further increase the production of breastmilk. Others will use it with alfalfa, stinging nettle, or goat's rue.

Some commercially prepared milk-boosting products (such as Traditional Medicinal's Mother's Milk Tea, Motherlove's More Milk, and More Milk Plus) contain blessed thistle and other herb galactagogues.

What to Look For

Herbal remedies are not strictly regulated in the United States. Because of this, the quality can vary from one brand to the next. To ensure better quality and safety, stick with well-known supplements manufacturers with an established market presence.

While many vitamin manufacturers will submit the products for voluntary inspection by the U.S. Pharmacopeia (USP), ConsumerLab, or other independent certifying bodies, herbal supplements manufacturers are less likely to do so.

For an added layer of safety, choose supplements that have been certified organic under the regulations of the U.S. Department of Agriculture (USDA). Doing so can reduce your risk of exposure to pesticides, heavy metals, and other common contaminants.

Other Questions

How long does it take for blessed thistle to work?

Like all herbs, blessed thistle doesn't work for everyone. However, some breastfeeding mothers report an increase in breast milk after using blessed thistle for only a few days. When fenugreek is also taken, blessed thistle appears to work even better.

For the best results, breastfeed more often or pump after or between feedings. Blessed thistle is more likely to work when there is an increase in breast stimulation.

5 Sources
Verywell Family uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Al-Snafi AE. The Constituents and Pharmacology of Cnicus Benedictus - A Review. The Pharmaceutical and Chemical Journal. 2016;3(2):129-135.

  2. Di Pierro F, Callegari A, Carotenuto D, Tapia MM. Clinical efficacy, safety and tolerability of BIO-C (micronized Silymarin) as a galactagogue. Acta Biomed. 2008;79(3):205-210.

  3. Szabó I, Pallag A, Blidar CF. The antimicrobial activity of the Cnicus benedictus L. extracts. Analele Universitatii din Oradea, Fascicula Biologie. 2009;16(1):126-128.

  4. Steenkamp V, Gouws MC. Cytotoxicity of six South African medicinal plant extracts used in the treatment of cancer. S Afr J Bot. 2006;72(4):630-633. doi:10.1016/j.sajb.2006.02.004

  5. Ulbricht C, Basch E, Dacey C, Dith S, Weissner W. An Evidence-Based Systematic Review of Blessed Thistle (Cnicus benedictus) by the Natural Standard Research Collaboration. Journal of Dietary Supplements. 2008;5(4):422-437. doi:10.1080/19390210802519754

Additional Reading

By Donna Murray, RN, BSN
Donna Murray, RN, BSN has a Bachelor of Science in Nursing from Rutgers University and is a current member of Sigma Theta Tau, the Honor Society of Nursing.