Educational information, not medical advice — ask your doctor or midwife.
Lapacho is the inner bark of a South American tree, Handroanthus impetiginosus. It is also sold as pau d'arco or taheebo. The tree is often called the pink trumpet tree.
The dried bark is used as a tea, a tincture or a capsule. Folk healers in Brazil, Paraguay and Argentina used it for many complaints. Long traditional use is not proof that it works, and it is not proof that it is safe.
Human evidence is thin. No good trial shows that lapacho treats any disease. One bark compound, lapachol, caused bleeding problems and vomiting when tested in people in the 1970s.
That bleeding risk is the main reason to be careful. If you take a blood thinner, or you are pregnant, this is not a herb to try.
No one has shown how lapacho works in people, because no clear effect in people has been shown either. Almost all the research is lab research. That tells you little about what a cup of bark tea does.
In test tubes, compounds from the bark slow some fungi, bacteria and parasites. In cell studies, beta-lapachone harms certain cancer cells. These results come from dishes and animals, not from patients.
Lapachol appears to block vitamin K in animal work. Vitamin K is what the body uses to form blood clots. That may explain the longer clotting times seen in early human testing.
Amount matters too. Bark sold for tea often holds very little lapachol. A lab result at a high dose may say nothing about your cup.
Lapacho is sold mainly as dried inner bark for tea. Capsules, tablets, tinctures and liquid extracts are also easy to find.
Tea is the traditional form. The bark is simmered in water rather than steeped like a tea bag.
Capsules and tablets hold powdered bark or a dried extract. Tinctures are alcohol-based liquids taken in drops.
You may also meet it inside mixed herbal blends, skin creams and soaps. Some blends list it only as taheebo or pau d'arco.
Labels rarely state how much lapachol is inside. Two products with the same name can differ a lot. That makes the strength of any given product hard to judge.
Peoples of the Amazon and the Gran Chaco used the inner bark for generations. Healers in Brazil, Paraguay and Argentina carried the use forward.
It was given for fevers, skin sores, fungal problems and stomach upsets. Some groups also used it for pain and for wounds. The wood itself was prized for bows, which is where the name pau d'arco comes from.
In the 1960s, Brazilian press reports claimed the bark helped cancer patients. Exports rose sharply. The United States National Cancer Institute then tested lapachol in patients.
That testing was dropped. Doses high enough to act on tumours caused side effects instead. Sales of the bark carried on anyway.
Stop taking it and speak to a doctor if you notice any of these:
Unusual bruising, bleeding gums or nosebleeds. Blood in your urine, or black or bloody stools. Yellow skin or eyes.
Also stop for repeated vomiting, bad stomach pain, or dizziness and unusual tiredness.
Get emergency help for bleeding that will not stop, or for vomit that looks like coffee grounds. Tell the staff that you have been taking pau d'arco.
In the United States, lapacho is sold as a dietary supplement. It is not approved as a drug for any condition.
In the UK and the EU it is sold as a herbal tea or food supplement, not as a licensed herbal medicine. Canada licenses some products as natural health products.
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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