Pau d'arco (Tabebuia avellanedae) is native to South America, where it has been used to treat a wide range of conditions, including pain, arthritis, inflammation of the prostate gland (prostatitis), fever, dysentery, boils and ulcers, and various cancers. As early as 1873, there were reported medicinal uses of pau d'arco.
Scientists have identified two active chemicals in pau d'arco. These chemicals are called naphthoquinones: lapachol and beta-lapachone. In lab tests, these chemicals killed some bacteria, fungi, viruses, and parasites. They also have anti-inflammatory properties and may be effective against diseases such as osteoarthritis. But no one knows whether they will have the same effects in humans, and the dose required would have severe, toxic side effects.
Pau d'arco is sometimes used for the following conditions, although there is no evidence it works:
Candidiasis (a vaginal or oral yeast infection)
Herpes simplex virus
Parasitic diseases, such as schistosomiasis
Bacterial infections, such as brucellosis
Test tube and animal studies have looked at whether pau d'arco has any effect on cancer. These tests have shown mixed results. Even in studies where pau d'arco did reduce the number of cancer cells, the amounts used would be toxic to humans.