I have been working with and researching pau d' arco (lapacho, taheebo, ipe roxo, tabuei) for about 29 years. It does have a lot of great properties containing 18 antiseptic anthraquinones and napthaquinones and 5 anti-inflammatory compounds. It is more effective when combined with sulfur bearing herbs. Traditionally it is combined with yerba mate', which I don't recommend due to the caffeine content. I prefer to combine it chaparral, which is also a full range antimicrobial, immune stimulant and anti-inflammatory.
It is believed that Candida builds up a resistance so people will often rotate with other antifungals, such as mathake, after a month or two, then eventually rotate back.
But again it is impossible to kill off all the Candida in the body. Just like our flora and staphylococcus bacteria, these are all naturally found in the body and cannot be completely eradicated. The only way to get Candida back under control, which is the norm, is to create an inhospitable environment for its growth and to keep it in a yeast form as opposed to its pathogenic fungal form. To do this the terrain in all areas of the body where Candida normally exists must be kept acidic. This turns off the Candida growth gene and keeps the Candida in its relatively harmless yeast form. An alkaline environment, such as occurs after Antibiotic use, turns the Candida growth gene on and converts the Candida in to its pathogenic and highly aggressive fungal form.