For me personally, energy healing (and I use the term loosely because pretty much all metaphysical work involves energy work of some sort) does not have to come with any adverse consequences. There are many ways to heal someone ranging from physical contact, astral projection, using universal light energy, using vibrations, crystals, etc. I use universal light energy when performing healings. It's just a matter of drawing in the energy in from the universe and using it to heal a person. Universal light energy is limitless and always available, and since I am not using my own energy, I don't feel drained.
As for the purity of the transferred energy...I find the most important thing is the intent behind the action. A source of energy pure or not, won't do much good, if my intentions are not pure.
If you are interested in healing, I suggest you do research on the subject (a lot of research). If it's for you, you will find the topic exciting and fascinating enough to keep researching until you find something that resonates for you.
As always...ground, center, and shield before performing any metaphysical work.
Just my thoughts on the subject.