Is it ok to take prescription Phentermine tablets with a training supplement?

My fiancee has prescriptions for Phentermine Chloride tablets and B12 vitamins and has been taking them for almost a year now and has lost over 100 pounds. The only downfall is that with this amazing weight loss, his skin didn't keep up, and it's not as tight as he would like it. An acquaintance of his gave him these training supplements called "Animal." He says the pills are supposed to help his skin and body tone up. The can says they're "animal training packs" and "the complete cutting stack." Inside of the can there's these plastic pouches filled with these pills that he's supposed to take everyday. They look like vitamins, and he tells me that they're herbal supplements and definitely not steroids (he would never take them, and he knows that I am against them). What I want to know is, is it safe to take his prescription as well as these supplements? The can says do not take if you are using a MAOI or any other dietary supplement, prescription drug containing psuedoephedrine, ephedrine, or phenlypropalamine (an ingredient in allergy, cough/cold and weight loss products). I have been searching to find out what is in his phentermine pills but it doesn't say the ingredients. And his B12's are just a vitamin. Can anyone please help and tell me if it's safe or not? Thank you very much!