Soap is basically made from drain cleaner and oil. There is no way to do it otherwise; melt-and-pour soap means you just buy the stuff after the drain cleaner has reacted with the oil.
This means that it is a very bad idea to eat raw soap. Which my "baby" (approaching 30!) brother discovered this weekend. Fortunately this batch was a remilling of cold-process that went wrong, therefore it was cooked, thus way less hazardous than it could have been (i.e. he didn't end up burning out his entire GIT). But hey, what a nasty way to wake up. He turned out fine, but foamed at the mouth all day. Now that I know he's fine, and the adrenaline has cleared out, it's kinda funny.
So: if you get raw soap on your skin, or other surfaces, the best thing to do is to rinse off with vinegar. Caustic soda is alkaline; the vinegar neutralises it.
BUT if you eat it drink milk, not acidic fluids like orange juice; the reactions of the acid & alkaline will exacerbate any burn. DO NOT INDUCE VOMITING. Call a doctor.
All things considered, it's best to leave internal cleansing to nettle or buchu teas.