Educational information, not medical advice — ask your doctor or midwife.
Cardo mariano is the Spanish name for milk thistle (Silybum marianum). It is taken mainly as a liver supplement. The seeds are the part used.
The plant is tall and spiky, with purple flower heads and white-veined leaves. It grows wild across Mexico, the Andes and the Southern Cone. Most supplements use a seed extract rich in silymarin.
Here is the short verdict on evidence. Human trials exist, but they are small, mixed and often weak. It is widely used and usually well tolerated, yet it is not proven to treat liver disease.
One point to hold onto as you read. Long traditional use is not proof that a remedy works, and it is not proof that it is safe.
Most of what is claimed for cardo mariano comes from the lab, not from people.
In cell and animal studies, silymarin appears to protect liver cells from damage. It seems to mop up free radicals, which are unstable molecules that harm cells. Animal work also suggests it may calm signals linked to inflammation.
In test tubes, silybin appears to block some toxins from entering liver cells. This idea sits behind its hospital use in death cap mushroom poisoning.
Whether any of this matters at supplement doses in people is not settled. Blood levels after capsules are low, because silymarin is poorly absorbed. That gap between lab result and real effect is the main open question.
Capsules or tablets of standardised seed extract are the most common form.
You may also see:
- whole or ground seeds, sometimes stirred into food - seed tea or infusion, common in home use - tinctures, which are alcohol extracts - silybin bound to phosphatidylcholine, a fat used to improve uptake - blended "liver support" formulas with other herbs
There is also a hospital form. An injected silibinin medicine is used in some countries for death cap mushroom poisoning. It is a prescription drug given by doctors, not a supplement you can buy.
Milk thistle was used in Europe for liver and bile complaints since at least Roman times.
Spanish settlers carried the plant to the Americas, where it spread as a roadside weed. Local herbalists took it up under the name cardo mariano. They gave it for jaundice, gallbladder pain and liver trouble after heavy drinking.
In Mexican and Andean home medicine it was also used for poor appetite and sluggish digestion. Seeds were usually boiled or ground.
The name comes from an old legend. Milk from the Virgin Mary was said to have fallen on the leaves, leaving white veins.
Stop and get emergency help if you have swelling of the lips, face or throat, a widespread rash, or trouble breathing.
Stop and see a doctor if you notice yellow skin or eyes, dark urine, pale stools, or pain under the right ribs. These can be signs of liver trouble and need testing.
Also see a doctor if diarrhoea lasts more than a few days. If you have diabetes, report readings that run lower than usual.
In the United States, the European Union and most of Latin America, milk thistle is sold as an ordinary food supplement. It is not approved as a medicine for liver disease. The injected silibinin product used for mushroom poisoning is a prescription hospital drug.
Evidence grades and traditional-use labels are explained in our methodology. Nothing here is medical advice.
What it is typically used for, usual dose, cautions, and the study behind it where real trial data exists.
One email with the summary. We'll also send a short weekly evidence update — unsubscribe any time.
