I do not know about the Pau D'arco, but I do know that when I was making Essiac under the directions of my Naturopath as part of a holistic cancer protocol, we were not allowed to sweeten the Essiac specifically because things like parasites and yeast like sugars/honey/syrup and we did not want to encourage that. I could use Stevia however. I used the liquid Stevia, its strong and the taste is different but I did eventually grow accustomed to it. I down Essiac without anything now. I use the caps everyday but a few months ago bought the liquid Essiac and downed my 2 ounces a day like a couple of shots.