Alternative healthcare is not illegal in any state provided that the service is performed by a qualified person. Many procedures are limited to physicians because of the medical licensing act. I believe a previous post stated that 'cleansing' is illegal/criminal in NY. This would certainly not be the case for a licensed physician. Drug and alcohol detoxifications are routinely performed and they are not illegal. Enemas are administered, and fiber is often recommended...all of which are aspects of 'cleansing'. This may be more of an issue of semantics than law. While there are cases of physicians who practice on the fringe of what is considered 'medicine' and have had their practices closed or licenses revoked, the vast majority of alternative/complementary practitioners do not encounter this. This often occurs as a result of unsubstantiated claims for curing particular illnesses (even though there may be anecdotal evidence to support their claims). Unfortunately it also occurs because of disgruntled patients who have not been 'cured' and express their anger in the form of lawsuits.
While there are some limitations regarding the services that physicians can administer, there are many natural and alternative or complementary therapies that are within their legal realm.