Educational information, not medical advice — ask your doctor or midwife.
Picão-preto is a common roadside weed drunk as a herbal tea in Latin America. Its botanical name is Bidens pilosa. In English it is called beggarticks or blackjack, after its barbed seeds that stick to clothes.
The leaves and stems are the parts used. Folk healers reached for it for stomach upset, swelling, wounds and high blood sugar. In parts of Africa the young leaves are cooked and eaten as a green vegetable.
Here is the honest verdict. Almost all the research sits in test tubes and in rats and mice. Long use in folk medicine is not proof that it works, and it is not proof that it is safe.
No one has shown how this plant works in the human body. The proposed ideas all come from lab dishes and animals.
In mice and rats, extracts of Bidens pilosa have lowered blood sugar. A compound called cytopiloyne appeared to protect insulin-making cells in those animals.
In cell studies, its flavonoids damp down some signals linked to swelling. Whether that happens in a person who drinks the tea is not known.
Animal work also points to a mild water pill (diuretic) effect and slightly lower blood pressure. These results have not been confirmed in people.
Lab tests show the extract slows some bacteria and parasites in a dish. That does not mean it treats an infection in the body.
Dried leaf and stem for tea is the most common form.
Forms you may see on sale: - loose dried herb for tea, sold in markets and health shops - capsules of dried, powdered leaf - tinctures and liquid extracts made with alcohol - creams, oils and washes for the skin - fresh leaves, used in home remedies and cooked as greens
These products are not standardised. Two brands can differ a lot in strength, and so can two bags from the same brand.
Labels rarely state how much of any single compound is in the product. That makes it hard to compare one product with another.
Picão-preto has been used in Latin American folk medicine for centuries. Healers in Brazil, Peru, Mexico and the Caribbean brewed the leaves as a tea.
Old records describe its use for liver and stomach complaints, fevers and sore throats. Crushed leaves were packed onto cuts and insect bites.
The plant spread around the world as a farm weed. Much the same uses grew up in Africa, China and the Pacific islands.
In Brazil it remains a well known home remedy. The health ministry lists it among plants of interest for study in the public health system.
Stop using it and see a doctor if any of these happen: - yellow skin or eyes, dark urine, or pain under your right ribs - a rash, swollen lips or tongue, or trouble breathing - shaking, sweating, confusion or faintness, which can mean low blood sugar - vomiting or diarrhoea that lasts more than a day - dizziness when you stand up
Get urgent care for breathing trouble or for confusion that does not clear with sugary food. Tell your doctor you have been taking picão-preto.
In Brazil it is a well known home remedy and sits on the health ministry's list of plants of interest for study in the public health system. In the United States it is sold as a dietary supplement and is not approved by the FDA to treat any disease. It has no approved herbal monograph in the European Union.
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.
