Taken internally, it is thought to relieve infections, reduce inflammation, and promote good digestion. Anecdotal reports claim that it causes tumor regression. Applied externally, pau d arco is a common alternative remedy for inflammatory skin conditions, fungal infections, hemorrhoids, eczema, and wounds. Pau d arco is available as capsules, tea bags, or loose powder. Medical research has identified several compounds in pau d arco that produce some effects against disease.
Interest focuses on lapachol, an organic compound classified as a naphthoquinone.
In laboratory animals, lapachol appears to be effective against malaria. A study, also in animals, found that lapachol had potent activity against certain kinds of animal tumor cells, such as sarcoma, but did not have effect against other kinds, including leukemia and adenocarcinoma. The bark extract also may work to kill bacteria or fungi. Proponents claim that lapacho stimulates production of red blood cells, which in turn improves the oxygen-carrying capacity of the blood and contributes to healing. The bark contains at least 20 other active compounds, including quercetin and other flavonoids, whose effects are not yet known.