I'd be interested in hearing more study wise, but I am gonna say I doubt very much you would have long term health issues. It's been consumed by man for a long time...and of all the reasons the gov tries to convince you not to use, I have never heard liver mentioned.
That being said, I am sure if your liver is already compromised you may want to consult your doc. Otherwise, I am sure it is alot easier on your liver than most prescription meds.
Edit: And for the record, I would rather eat herb than take a tylenol any day...that shit will kill your liver.