What do you mean by "empirical"? Are you saying that eastern medicine is not based on empirical evidence, ie. observation and experimentation, but on some other approach?
If we put something through that process and find that outcome, we classify it as medicine. My understanding is that tests of some Traditional Chinese Medicine (which I assume is what we're talking about here when we say "eastern medicine") aren't able to replicate successful outcomes and so we therefore don't classify those things as medicine in the west.
That's not to say they don't help trigger the placebo and so on, just that we haven't proven it through double blind studies and so on - which is my understanding of what OP means by "empirical".
If you have any relevant sources that prove other wise I'll be happy to change my mind.