How do you advise a patient with CKD who wants to take an herbal medication that is not known to be nephrotoxic, given that herbal medications are not regulated?  

Dr. @Berns' answer is spot on. We just don't know what these drugs do in CKD. We have been fooled many times in the past, thinking it was safe, and they were not. But not all supplements are the same, and you have to look at the bottle; many are just homeopathic nonsense and can be taken. 

This can be challenging... people love their supplements/herbals. I tell them that they are unregulated, there is uncertainty as to contents including what the main ingredient is mixed with, and we have no idea how herbals interact with each other and with prescribed medications. I discourage but ad...