"Pau d'arco is a tree that grows in the Amazon rainforest and other tropical regions of South and Central America. Pau d'arco wood is dense and resists rotting. The name ""pau d'arco"" is Portuguese for ""bow tree,"" an appropriate term considering the tree's use by the native peoples of South America for making hunting bows. The bark and wood are used to make medicine. People use pau d'arco for conditions such as infections, cancer, diabetes, stomach ulcers, and many others, but there is no good scientific evidence to support these uses. Using pau d'arco can also be unsafe, especially at higher doses. Commercial products containing pau d'arco are available in capsule, tablet, extract, powder, and tea forms. But sometimes it's hard to know what is in pau d'arco products. Some studies have shown that some pau d'arco products sold in Canada, Brazil, and Portugal do not contain the active ingredients in the correct amounts."