Not a miracle pill for kidney disease in cats.
My holistic vet recommends this.  I am Chinese, and I have faith in Chinese medicine.  More importantly, I can read things about this medicine written in Chinese.  The formula has been out there for many years for humans.  You need to know there are two versions of this med: Rehmannia six and eight.  Rehmannia six is for pets who easily overheat.  Rehmannia eight has two more ingredients than Rehmannia six and is good for pets who tend to seek warmer areas to sleep (which means they prone to get cold).  Anyway, my cat didn't get any better in terms of blood work.  In fact, all the kidney numbers like Bun and Crea went way up by A LOT.  In the meanwhile,  my cat has been under fluid therapy and this med, so Rehmannia Eight really didn't help at all to bring my cat's kidney's number down.  I don't know how to feel about this med - it didn't make anything worse, nor did it help.  Maybe try it for a month and get your pet a blood test for final decision.
Rating: 4 stars