I told my previous pdoc "no" on a handful of occasions and he didn't respect that. It got to the point where I gave up on saying "no" and started doing whatever I wanted, including starting/stopping certain meds, and changing doses on my own. It was bad. He was toxic. However, he left the practice and I got a new pdoc (who is my current pdoc) in the same practice. My current one *sometimes* respects my "no" answers, but not always.

I really think it depends on the pdoc, but it doesn't hurt to say "NO." You can never negotiate a situation if you don't try in the first place.