Can you have gain without pain? It's human nature to want to avoid it, but healing principles, as I understand them, pretty much demand that some price will be paid during a correction. The best thing they can do is build up their eliminatory organs. Have them take plenty of apples & pectin to keep the blood as clean as possible, salt, etc.
I haven't suffered much by way of detox symptoms since I started iodine & have done the mini-beet protocol & water fasting, but I have had to deal with it from time to time. I'd actually have been worried if I didn't have any, because I wouldn't be sure anything was happening, and I've had just as much crap in me as anyone else.