Educational information, not medical advice — ask your doctor or midwife.
Palo de arco is the inner bark of a South American tree, Handroanthus impetiginosus. English labels usually call it pau d'arco or pink trumpet tree. It is sold as a tea, a capsule, a tablet or a liquid extract.
People take it for fungal and bacterial infections, for aches, and as a general "cleansing" tonic. Healers in Brazil, Paraguay and Argentina used the bark for a long list of complaints. Long use in a tradition is not proof that it works, and it is not proof that it is safe.
Here is the honest verdict. Good human studies are missing, so none of the health claims are settled. The bark also carries a real bleeding risk, which is why this page treats it with care.
The tree itself is well known in Latin America for its bright pink flowers. The bark trade is large, and what is in a bag or capsule varies a lot. Some products are mixed with, or swapped for, other Tabebuia-type barks.
The short answer: no one has shown how it works in people.
The bark holds naphthoquinones (a group of plant chemicals), mainly lapachol and beta-lapachone. In test tubes, these slow the growth of some fungi, bacteria, viruses and parasites. Whether that happens inside your body after a cup of tea is not known.
In cell and animal studies, beta-lapachone appears to damage DNA in fast-growing cells. Drug companies have used it as a starting point for new drug research. That work is about a purified compound, not about bark tea.
Lapachol can act like a blood thinner (anticoagulant) in animals. It appears to work against vitamin K, which your blood needs in order to clot. This lab and animal finding is the main reason the herb is handled with caution.
Lab work also suggests the bark can calm inflammation signals in cells. Again, that has not been matched by clear results in people.
You will usually find it as:
Dried shredded inner bark, simmered as a tea.
Tea bags labelled pau d'arco or taheebo.
Capsules and tablets of powdered bark.
Liquid extracts and tinctures in alcohol or glycerine.
Skin creams and salves, often sold for fungal or itchy skin.
A few points are worth knowing before you buy. Bark quality is not tightly policed, and mislabelling is common. Products sold as "taheebo tea" may contain outer bark or other species.
Indigenous and rural communities in Brazil, Paraguay, Argentina and Bolivia used the inner bark for generations. It was simmered into a dark tea and given for fevers, infections and skin complaints.
In the 1960s the bark drew wide attention after Brazilian press reports linked it to cancer. That led the US National Cancer Institute to study its compound lapachol. Interest in the raw bark grew into a large export trade.
In herbal practice it was also used for stomach trouble, joint pain and "blood cleansing". These were traditional uses recorded by writers and healers. They describe what people did, not what the bark was shown to do.
Stop taking it and see a doctor if you notice:
Bruising that appears without a knock.
Nosebleeds, bleeding gums, or cuts that keep bleeding.
Heavy or unusual periods.
Vomiting that will not settle.
Unusual tiredness or pale skin, which can mean low red blood cells.
Get emergency help straight away for blood in your urine, black or bloody stools, vomiting blood, a severe headache, or sudden confusion. These can be signs of serious bleeding.
Also see a doctor if the infection or pain you are treating is not getting better within a few days.
In the United States it is sold as a dietary supplement. It is not approved as a drug for any illness there.
In the UK, EU, Canada and Australia it is sold as a herbal or food supplement. Health claims on the label are limited by law.
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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