Hi, I don't think you need to do a mastercleanse first, but I suggest alot of water and bowel cleansing for at least a week to keep things moving along. You will be passing stones and toxins and want to get things out of your body quickly. I like psyllium and the such. Dr Schulze has good formulas too. Check with pricing....and check with Raider on the Schulze Forum as she is placing an order this week and gets a discount.