Pau d'Arco.
Inner bark of a South American tree, traditionally simmered into taheebo tea. Its naphthoquinones, chiefly lapachol, are what the plant is known for, and they barely dissolve in water.
- Category
- Herb
What Pau d'Arco is, and what it does.
- Does it work
- Suits people drawn to traditional South American bark teas who will check botanical identity before buying. If you take a blood thinner, speak to your clinician first.
- How much to take
- No daily amount is on record and we won't invent one. Traditional use is a simmered inner-bark tea, and water carries far less naphthoquinone than an alcohol extract.
- Time to feel it
- Nobody has measured a time to effect in people. With 68 published records at Europe PMC, the human timeline is simply not in the literature.
- The first dose
- Day one is a bitter, woody tea and little else. No measured change has been recorded in the first 24 hours.
- With regular use
- Weeks of use have not been tracked in people. Older pharmacology describes interference with vitamin K dependent clotting factors at amounts well above what a bark tea delivers.
- How well tolerated
- Take this one seriously. Lapachol resembles vitamin K and can interfere with normal clotting at high amounts. Avoid in pregnancy and check with a clinician if you take any medicine.
- How it feels
- Bitter, woody and a little astringent as a tea. Beyond taste, most people report no particular sensation and none has been measured.
- The overlooked benefit
- Retail analyses have repeatedly found little or no lapachol, since wood, outer bark and other species trade under the name. Species and plant part tell you more than the front label.
The proof, claim by claim.
These words describe the research, not the molecule's worth. Research strength is how much work stands behind one claim, and it is never a product score.
- Naphthoquinone antimicrobial activity in cultureIn vitro study
- Lapachol interference with vitamin K dependent clotting factorsNarrative review
- Traditional use of the inner bark as taheebo teaNarrative review
- Naphthoquinone redox cycling and cellular toxicity at higher amountsIn vitro study
Why these belong in the same formula. Each row says what the basis is, from settled biochemistry through to a trial that measured the pair.
Lapachol and vitamin K share the naphthoquinone ring that the recycling enzyme recognises. High-dose lapachol has been described as antagonising vitamin K dependent clotting factor synthesis, and vitamin K is the counterweight. Anyone on a vitamin K antagonist is in exactly the wrong place for this combination and should be talking to whoever manages their anticoagulation.
Nattokinase has fibrinolytic activity and lapachol can interfere with clotting factor production. The two act at different points but push the same direction. Combining them raises bleeding risk without any evidence that the combination does anything useful.
Long-chain omega-3 fatty acids reduce platelet aggregation through changes in eicosanoid production. Stacking that with a naphthoquinone that can interfere with clotting factors compounds the effect. Worth flagging before any procedure with a bleeding risk.
Ginkgolides antagonise platelet-activating factor, and pau d'arco adds a separate route to impaired clotting. The two together carry more bleeding risk than either alone. This is an interaction to flag, not a pairing to build around.
Allicin-derived sulfur compounds inhibit platelet aggregation at supplement doses. Adding pau d'arco stacks a second mechanism affecting haemostasis on top. The combined effect deserves attention around surgery or dental work.
Ascorbate reduces quinones to hydroquinones, and the redox couple can either quench or accelerate cycling depending on the local oxygen and metal environment. Direction is not predictable from first principles for this pairing. Read it as an open question rather than as a benefit.
Lapachol is lipophilic and barely soluble in water. A lipid vehicle keeps far more of it in solution through the gut than an aqueous preparation does. That raises what gets absorbed, which cuts both ways given the dose-dependent toxicity.
Naphthoquinones are metabolised in the liver and redox-cycling compounds place a demand on hepatic glutathione. Silymarin is commonly added alongside herbs with that profile. The pairing is convention among formulators and has not been tested for this combination.
Nothing specific on file for Pau d'Arco. Match the label to the daily amount above, and tell your doctor what you take.
Not medical advice. Show the label to your pharmacist.What Pau d'Arco actually does.
Pau d'arco is a South American tree bark whose signature compounds are naphthoquinones.
These compounds generate reactive oxygen inside cells, which cuts both ways depending on dose.
Lapachol looks chemically like vitamin K, which is how it can interfere with normal clotting.
A lot of what is sold as pau d'arco is the wrong part of the tree, or the wrong tree.
Where Pau d'Arco comes from.
The inner bark of a South American tree, traditionally boiled into a tea called taheebo. Its active compounds barely dissolve in water, so a tea and an alcohol extract are very different products. One of those compounds resembles vitamin K closely enough to interfere with normal clotting at high doses, which is the main reason to be careful with it.
Made from a plant. What ends up in the capsule tracks the harvest, so batch testing and a stated marker matter more here than with a made molecule.
A Bignoniaceae timber tree of Central and South America. Only the inner bark, the phloem layer beneath the corky outer bark, carries the naphthoquinones the herb is known for.
The step that most often goes wrong commercially. Outer bark and wood are cheaper and heavier, and both are low in lapachol.
Water pulls tannins and a small share of the lapachol. Ethanol or lipid extraction pulls much more of the naphthoquinone fraction, producing a materially different product.
Extracts are concentrated under vacuum and spray dried onto a carrier for capsule filling.
Where standardisation is done at all. Independent analyses of retail material have frequently found lapachol at or near the limit of detection.
Sold as loose bark and tea bags, as capsules of milled bark, or as concentrated liquid and dry extracts.
The forms it comes in.
The essence, in one line each.
- A single-arm open-label study reported tolerability of a Pau d'Arco preparation in women with recurring period pain. With no comparator group, nothing observed can be attributed to the herb rather than to time or expectation.Open-label trial. McClure C et al., 2022 (Advances in Integrative Medicine). PMID 36960315 ↗
- Changes in body composition, blood pressure and lipid measures were reported in adults following a multi-component dietary programme in which pau d'arco was one of many ingredients. Nothing in the result can be assigned to pau d'arco specifically.Open-label trial. Balliett M et al., 2013 (Journal of Chiropractic Medicine). PMID 23997718 ↗
These are the studies our verdict leans on, chosen from the 2 we read for Pau d'Arco. The full linked list is below.
FDA Disclaimer: These statements have not been evaluated by the Food and Drug Administration. This information is for educational purposes only and is not intended to diagnose, treat, cure, or prevent any disease. Consult your healthcare provider before starting any supplement regimen.