My definition of alternative vs modern medicine is how they approach it. Alternative focuses on the whole body. Modern, just on the symptom. If you treat just the symptom without getting to the root of the problem, you'll never get better. I've researched Ayurveda before, as well as many other alternative medicines. It's based off of 3 dosha types- vata, kapha, pitta. While I never subscribed to the dosha types, I had learned a lot about keeping healthy. 
Some use it as a stand-alone for health, others in association with conventional modern medicine. For those who are into Ayurveda, do you use it alone or combine it with others?