The only way you are going to get some consistency with dosing is with a standardized extract. I have never seen a standardized extract for pau d' arco. They do make extracts like 4:1, 10:1, etc, but not standardized. I never use standardized extracts anyway because plants have more than one active component, and so what are you going to standardize it for without changing the effectiveness or properties? For instance I can standardize alfalfa for its coumarin content, but this will make it a strong blood thinner since it is no longer balanced by the vitamin K in the alfalfa. Another great example is Saint Johnswort (SJW), which was originally standardized for hypericin, which they thought was the active component. Then they thought the active component was hypericum, so they standardized it for that. Then they thought it was the flavonoids..... What they did not realize is that it was all the components working in conjunction with each other.

So if they want to standardize pau d arco what are the going to standardize for? Which of the 18 anthraquinones and napthaquinones? Or are they going to standardize pau d' arco with one of the 5 anti-inflammatories it contains?

This is why I rarely use any type of isolated plant extracts. I figure nature knows what it is doing and these plants have worked well for us for thousands of years as is.

Pau d' arco is relatively safe. Side effects of very high doses are diarrhea and some blood thinning. In rare cases people have developed allergies to the bark. And it is high in iron, so it is not recommended in cases of hemochromotisis.