Alternative medicine, by definition, is medicine that is not supported by good enough evidence to have earned it a place in mainstream medicine.
Some people insist that modern medicine is not evidence-based either! Not long ago I got an email from a man who said that and tried to prove it with a series of arguments that were all fallacious. These are zombie arguments that keep staggering back to life after they have been thoroughly eviscerated and buried. Skeptics can only refute them over and over in a Sisyphean effort.
Read the article by Harriet Hall: http://www.csicop.org/specialarticles/show/zombie_criticisms_of_conventional_medicine/