← The ApothecaryAsteraceaeflowering aerial partsFact-checked 24 October 2026

Blessed thistle

Centaurea benedicta

Also calledHoly thistle · St Benedict's thistle · Kardobenediktenkraut (German) · Cnici benedicti herba (dried herb)

In older monographsCnicus benedictus, Carduus benedictus, Carbenia benedicta

A Mediterranean thistle named 'blessed' in Renaissance plague treatises, used for centuries as a bitter tonic for appetite and digestion and still a flavouring of Benedictine liqueur. The EU herbal committee accepts it as a traditional remedy for loss of appetite and dyspepsia. It is widely sold to increase breast-milk supply, but no valid trials support that use.

What it is used for

Poor appetite
Traditional
EMA traditional use for temporary loss of appetite, taken before meals. The bitter sesquiterpene lactone cnicin is thought to stimulate saliva and gastric juice reflexively, but EMA found no pharmacological or clinical studies demonstrating this.^1,2
Indigestion and dyspepsia
Traditional
EMA traditional use for symptomatic relief of dyspepsia and mild gastrointestinal spasms; handbooks list flatulent dyspepsia.^1,2
Breast-milk supply
Traditional
A purported galactagogue included in proprietary 'milk supply' mixtures, but LactMed states that no scientifically valid clinical trials support this use; EMA does not recommend it during breastfeeding for lack of safety data.^2,3
Wounds and cuts
Traditional
Historically applied externally to gangrenous and indolent ulcers, and listed in Polish therapeutic guides of the 1950s as a dermatological antiseptic. Old lab studies reported antibacterial activity of the herb and of cnicin, without complete data.²

How it is prepared

infusion

Comminuted dried herb as an infusion or decoction, taken before meals for appetite.

EMA monograph (2023): 1.5–3 g in 150 ml water, 3 times daily (4.5–9 g daily), adults only.

Poor appetite · Indigestion and dyspepsia

tincture

Tincture 1:5 or liquid extract 1:1, both in 25% ethanol.

EMA monograph (2023): tincture 3–6 ml or liquid extract 1.5–2 ml, 3 times daily.

Poor appetite · Indigestion and dyspepsia

powder

Powdered herb in solid oral forms.

EMA monograph (2023): 1–2 g, 3 times daily.

Poor appetite

Amounts are as recorded by the named source, not a recommendation.

Safety

Pregnancy: Avoid
Breastfeeding: Insufficient data
Children: EMA: not recommended under 18 (lack of data).

Interactions with medicines

antacids, H2-blockers and proton-pump inhibitorsMinorTheoretical: by increasing stomach acid it might reduce their effect (cited by EMA from NLM; not documented).
anticoagulants and antiplateletsMinorPlatelet-activating-factor antagonism has been described, which in theory may increase bleeding risk; not shown in humans.

Interaction checker →

Do not use if

Allergy to plants of the daisy family (Asteraceae)

Side effects

Stomach irritation, cramps, nausea and vomiting at high doses (more than 5 g per cup of tea)
Allergic reactions in people sensitive to Asteraceae

Toxicity

Used traditionally to bring on menstruation or abortion, which is why sources advise avoiding it in pregnancy. Elevated liver enzymes were reported in a woman taking a multi-herb 'Mother's Milk' tea containing blessed thistle.

In the healing traditions

European folk medicine
Cardo santo / Kardobenediktenkraut
Bitter to stimulate appetite and bile, for jaundice, flatulence and digestion; also used as a diuretic, sweat-inducer, emmenagogue, for fevers, malaria and plague sores, and as a cure-all.
Hagers Handbuch (1938); Newall et al. 1996 (as cited by EMA)
Western herbalism
Holy thistle
Lack of appetite, anorexia and flatulent dyspepsia, as infusion, liquid extract or tincture.
British Herbal Compendium (1992)

Active compounds

cnicin: bitter sesquiterpene lactone (0.2–0.7%); anti-inflammatory in rat paw-oedema tests; oral LD50 in mice 1.6–3.2 mmol/kg
lignan lactones (arctigenin, trachelogenin): other constituents
tannins (about 8%) and potassium-rich minerals: other constituents

History

Native to the Mediterranean and western Asia, it was brought into cultivation in Europe in the sixteenth century and praised as a heal-all in plague treatises, which gave it the name benedictus. It is one of the botanicals flavouring Benedictine liqueur.

Sources

Reference, not prescription. Nothing here is medical advice. Herbs can interact with medicines and be dangerous in pregnancy; tell your doctor or pharmacist about anything you take.