Educational information, not medical advice — ask your doctor or midwife.
Hog weed is a low, spreading weed used in Caribbean bush medicine, mostly as a tea for water retention and urinary complaints. Its botanical name is Boerhavia diffusa. In the Dominican Republic and Puerto Rico it is called yerba tostón.
This is not giant hogweed, the tall plant whose sap burns skin. Those are different plants with similar names. Check the Latin name on any product you look at.
The root and the whole plant are the parts used. The same species is called punarnava in Ayurveda, so most research is published under that name.
Human evidence is very thin. Nearly all the support comes from lab and animal work. Long traditional use is not proof that it works, and it is not proof that it is safe.
No one has shown how hog weed acts in the human body. The proposed actions come from animals and cells, not from people.
In rats, root extracts raised urine output and sodium loss. This matches the old use as a water pill (diuretic). It has not been measured properly in humans.
In cell studies, the boeravinones appear to damp down inflammation signals. In animal models of kidney and liver injury, extracts lowered some damage markers. Whether any of this happens in a person drinking the tea is unknown.
In diabetic rats, extracts lowered blood sugar. That is one reason for caution if you take diabetes medicine. It is not evidence that the plant treats diabetes.
Dried root and dried whole plant are the usual raw forms. In the Caribbean, the plant was simmered into a bush tea.
Capsules and tablets of powdered root are sold widely. Many are labelled punarnava rather than hog weed.
Liquid extracts and alcohol tinctures are also sold. Some multi-herb kidney, liver or swelling blends include it.
Young leaves are eaten as a cooked green in parts of the Caribbean and India. Food amounts are much smaller than supplement amounts.
Caribbean households kept hog weed as a bush tea for swollen legs, urine trouble and 'cleansing' the body. Healers in the Dominican Republic and Puerto Rico knew it as yerba tostón. In the Eastern Caribbean it was called pig weed.
The plant also has a long written record in Ayurveda as punarnava. Indian texts listed it for swelling, urine problems and liver complaints. These two traditions grew up apart but used the plant in much the same way.
It also served as a famine food and a fodder plant. Leaves were cooked and eaten when other greens ran short.
These records come from folk practice and herbal texts, not from trials. They describe what people did, not what the plant did.
Stop and see a doctor if you feel dizzy, faint, weak or cramped, or if your heart races. These can be signs of fluid and salt loss.
Get medical help the same day for swelling that is getting worse, breathlessness, or passing much less urine.
Go to urgent care for yellow skin or eyes, blood in your urine, or fever with back pain.
If you take lithium and feel shaky, confused or very thirsty, treat it as an emergency.
In the United States it is sold as a dietary supplement, often under the name punarnava. It is not approved there to treat any disease. In the UK and EU it is sold as a food supplement and is not a licensed medicine. Rules differ by country, so check your own.
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.
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