You have to positively demonstrate that a treatment is effective and safe enough to prescribe. It's not enough for something to have not yet been proven not to

You have to positively demonstrate that a treatment is effective and safe enough to prescribe. It's not enough for something to have not yet been proven not to work. Otherwise, you could sell gumdrops as a cure for cancer, because nobody has proved gumdrops don't cure cancer. Technically true, but not responsible medicine!