Well, bowel cleansing is definetely reccomended prior to Liver Flush as to not accumulate toxins from stones released (which can make you sicker). Certainly there's people who still go forward with the Liver Flush without having thorough Bowel Cleanse and still be fine but there's risk associated with it.
The Epsom Salts do help purge things before and after the flush (besides relaxing the bile ducts) so that on its own can do the trick for some people.
Good Luck
Mike