I would think that they can prescribe what they think is best. It's just his advice. You don't have to take it.
He should know what the risks are. You can also look them up yourself.
Other doctors may well have a different approach.
Medicine is not a science, it's an art, so treatment, attitudes and training will all vary.
That's why you must take control over it all.
Ask questions, research your problems, get different opinions.