Plenty of techniques that were once considered alternative medicine have found their way into Western medicine, so it's not all as cut and clear as you present it.
By definition, I begin
Alternative Medicine, I continue
Has either not been proved to work,
Or been proved not to work.
You know what they call alternative medicine
That's been proved to work?
Medicine.
For instance, check this guy:
“Calling ‘alternative medicine’ medicine is kind," says Dr. George Demetri, director of the Center for Sarcoma and Bone Oncology at the Dana-Farber Cancer Institute in Boston. "We need to be careful about how we use language. Show me an alternative medicine that works and I’ll show you a medicine that is no longer alternative.” http://www.prweb.com/releases/2012/11/prweb10183664.htm
Acupunture isn't accepted into western medicine because it doesn't actually work. It performs as good as any other placebo (reduces pain, makes patients feel better).
It's getting more mainstream, but that doesn't mean it's an accepted medicine.
A review of reviews:
http://www.painjournalonline.com/article/S0304-3959(10)00689...