How do we know Ayurveda has no side effects?
It has been time tested.
That is the beauty of herbology. If you take any medication through herbs, they do not have side effects. All the herbal medicines in the world, if you go through their webpage, they do not have any side effects, but if you take any of the herbs in excess it may not be good for you.
Like for example Triphala, is very good and it has no side effects but if you take too much of Triphala you will have diarrhea, but you cannot term that as a side effect.