Pau d'Arco (Lapacho) (Tabebuia impetiginosa)
What Is Pau d'Arco (Lapacho)?
Pau d'Arco (Lapacho) is catalogued in the Materia Medica under the binomial Tabebuia impetiginosa, a plant of the Bignoniaceae family, native to the American tropics. The material in circulation is inner bark — bark, stripped from stem or trunk. The common name Pau d'Arco (Lapacho) and the botanical name Tabebuia impetiginosa refer to the same material, and labels may use either — a detail that matters when related species in the same genus are not interchangeable. In the hand it reads as bitter, woody, slightly astringent, mild vanilla — a practical marker of freshness and correct identification.
The written history of Pau d'Arco (Lapacho) begins with household and practitioner use — recipes, harvesting notes and cautions passed between regions — and only much later with laboratory description of what the inner bark contains. Beyond its practical use it carries cultural associations — inca 'divine tree' — associated with strength and protection and used by Amazonian shamans for spiritual purification.
Today most searches for Pau d'Arco (Lapacho) come from people reading about antibacterial and antifungal, or checking how it sits alongside a medication they already take. The use most often documented in the literature is lapachol and β-lapachone have antifungal activity against Candida, followed by anticancer activity in preclinical models (topoisomerase inhibition).
How Does Pau d'Arco (Lapacho) Work?
Pau d'Arco (Lapacho) works as a mixture rather than a single isolated compound, and its profile is usually described by the class of constituents present in inner bark rather than by one marker molecule.
Before its chemistry was known, Pau d'Arco (Lapacho) was judged by what it did in the cup: how strongly it brewed, how it tasted, and how little or much was needed. Those notes are why particular preparations survived and others did not.
Published research is limited, leaning on small trials, laboratory work and animal models, and this profile cites 2 sources. Reported findings centre on Phase I trials of lapachol showed anticoagulant toxicity at therapeutic doses. Where research exists, it examines lapachol and β-lapachone have antifungal activity against Candida, anticancer activity in preclinical models (topoisomerase inhibition) and anti-inflammatory and antimicrobial against Gram-positive bacteria. These are areas of study, not established outcomes, and results differ by preparation and dose.
How the plant is prepared changes what you actually get. Its constituents move readily into water and alcohol — so a preparation made in another medium will not carry the same fraction of the plant, which is why traditional recipes specify one over another.
Pau d'Arco (Lapacho) is studied as a whole preparation because isolating one fraction tends to behave differently from the material it was taken out of — a recurring finding across the plant-chemistry literature.
Because these constituents are processed by the same pathways that handle many medicines, Pau d'Arco (Lapacho) is documented as interacting with anticoagulants and chemotherapy. That is a question of shared metabolism rather than of potency, and it is the main reason the plant is listed in interaction references at all.
Dose, plant part and growing conditions all shift the constituent profile, so two products carrying the name Pau d'Arco (Lapacho) can differ substantially; this is why reference entries specify inner bark and, where they exist, standardisation markers.