the dried rhizome i was buying didnt cause any unpleasant side effects at all. it didnt taste great it was from either India or Israel, India i think.
the only down side was, if you took a lot you became tolerant for 10-24 days. a lot was a coffee jar's worth. id pour boiling water over it, let it cool a bit and gulp it [liquid] down. the shop i was buying it from closed or id still but it. it was only £3-4/lb