Pau d’arco has antibacterial and anticancer activities in laboratory studies, but these effects have not been shown in humans.
Pau d’arco is derived from the inner bark of several species of Tabebuia trees native to South America. Also known as taheebo or lapacho, it is used as a tea in traditional medicine for a wide range of ailments. In laboratory studies, compounds extracted from pau d’arco showed antibacterial, antifungal, anti-inflammatory, antidepressant, and anticancer properties. However, data from human studies are limited. The safety and effectiveness of these compounds for treating cancer remain unclear.
To treat cancer
A small study done on 21 cancer patients did not show any benefits of pau d’arco. Side effects including nausea, vomiting, and blood thinning were observed.
To treat infections
Laboratory studies showed that pau d’arco has antibacterial and antifungal activities. It has not been tested in humans.
Do Not Take If
You are taking anticoagulants/antiplatelet drugs: Theoretically, pau d’arco may increase the risk of bleeding with these drugs.
Nausea, vomiting, urine discoloration.
Animal studies reported anemia, and reproductive and chromosomal abnormalities.
Pau d’arco is derived from the inner bark of several species of Tabebuia trees native to South America. Also known as taheebo or lapacho, it is used as a tea in traditional medicine for a wide range of ailments. Modern preparations in the form of oral tablets or capsules are marketed as dietary supplements to treat infections and cancer (1)(2)(3)(4).
In vitro and in vivo studies demonstrate antibacterial (5)(6), antifungal (7), antipsoriatic (8), immunomodulatory (9)(10), anti-inflammatory (11)(12), antidepressant (13), anticoagulant (10)(14) and anticancer (1)(2)(3)(4)(15)(16) properties. Human studies are needed to validate these effects.
In a small single-arm study, the naphthoquinone lapachol, at the given dose, did not show clinical improvement in patients with chronic myelocytic leukemia. Side effects including nausea, vomiting, and prolongation of prothrombin were observed (17).
Mechanism of Action
Lapachol and beta-lapachone, isolated from the inner bark of trees used to produce Pau d’arco, are thought to be the active constituents that are responsible for its pharmacological activities (20). Beta-lapachone downregulates cyclooxygenase (COX-2) and telomerase activities (1). It also induces apoptosis in cancer cells via mitochondrial signaling (2) or by activating caspases (5)(9)(2). The antimetastatic activity of beta-lapachone occurs by inducing Egr-1, known to suppress metastasis, thereby decreasing the invasive ability of cancer cells (4). A water extract of Taheebo showed anti-proliferative effects on hormone-sensitive MCF7 breast cancer cells by modulating gene expression, thereby interfering with cell cycle progression. At high doses, it also has anti-estrogenic effects through the inhibition of estrogen receptor signaling (16). A methanolic extract of taheebo inhibited cell proliferation through the extracelluar signal regulated kinase (ERK1/2) mitogen activated protein kinase (MAPK) pathway (10).
Lapachol’s anticoagulant activity is due to the inhibition of vitamin K epoxide and quinone reductases, an action similar to that of warfarin (14).
However, it is important to note that the clinical effects of Pau d’arco are difficult to predict because they are influenced by several factors including variation in plant species or plant parts, extraction methods, bioavailability of the active compounds, dosages and routes of administration.
Reported: Nausea, vomiting, urine discoloration (17) Anemia: Animal studies showed that large, chronic dosing of lapachol can cause anemia (21). Reproductive toxicity: Short-term administration of lapachol caused significant reduction in the weight of seminal vesicle (22).
Lapachol also has fetotoxic effects (23), and oral administration of lapachol caused chromosomal abnormalities (24).
Anticoagulant/antiplatelet drugs: Pau d’arco may increase their activity (25)(14)(10)
Herb Lab Interactions
Lapochol may cause prolongation of prothrombin time(17).