Hi,
I can't answer whether the Master Cleanse is safe or not. I thought it was when I did it obviously or I wouldn't have done it! I can tell you this. I wanted to cleanse my body of all the "junk" and wanted to start over with a cleaned out system ready to start eating healthier. Iinitially I just wanted to do it for the 10 days, but when I got to the 10th day I decided to try for the 30 day maximum. I made it to day 23 felt fine physically but felt mentally starved. The first 2 days was hard but when I set my mind to continue it was easy. I am considering doing it again but now that I am in nursing school and understand a little more about health and illness I want to research first about possible negative effects of the Master Cleanse. I would suggest you do the same.
Bottom line was I lost 21 lbs in 23 days; didn't follow my intention to eat healthy after that and gained all but 8 lbs back, but unless I see something somewhere about really negative effects of doing this cleanse I will opt to do it again!