Lapachol and beta-lapachone (known collectively as naphthaquinones) are two primary active compounds in pau d’arco. According to laboratory tests, both have anti-fungal properties as potent as ketoconazole, a common antifungal drug.¹ However, amounts of these constituents needed to exert an antifungal effect may be toxic to humans. Although these compounds also have anticancer properties according to test tube studies, the effective amount for this effect may also be toxic.^2,3 Therefore, pau d’arco cannot currently be recommended as a treatment for cancer.