Help: experienced cleansers...am looking for health info & the stright goods

I'm at the end of day 18 and feeling great. I just received a note from a friend who cautioned me against the cleanse sighting numerous potentially detrimental side effects of fasting (including a warning from the surgeon general). I have done lots of reading and haven't come across anything I felt was concerning. Does anyone out there have any info (links, books etc.) on negative effects of the cleanse?

Thanks & peace. Tweet