The page provides scientific documentation that flushing can and does work as well as providing warnings about the possible negative effects. Additionally, the page contains survey results from CureZoners who have done the flush.
In general, a Liver Flush is much safer than not doing it but there are a few cautions that should be observed.
If you have gall stones, they need to be removed somehow. The choices are chemotherapy which can take up to 2 years, ultrasonic shockwave therapy for a small number of stones, surgical gall bladder removal, or liver flushing. Of those who undergo gall bladder removal, 10 to 15 percent will have lifelong digestive system distress, including persistant diarrhea. The therapy with the lowest rate of problems is liver flush, but about 1 in 150 can experience a severe blockage of the pancreatic duct. In this case, you will end up needing the surgery anyhow.
There have been a few but very rare deaths after liver flushing, however, it is also quite possible that these cases were so severe that death may have followed any of the above therapies. For that reason, read the information thoroughly from the page linked to above. Start out slowly, do not try to do too much at once. Flush sooner rather than later because if you are badly bound up with stones, it will just make any therapy more difficult.