I dont think it necessary but beneficial. When i first started flushing i would catch a cold a day after the flush. This happend with the first 2 or 3 flushes. I think the reason this happens is because the stuff is pretty toxic that comes out of the liver and an enema helps get it out. However i no longer catch colds after a flush. You can do a flush and get benefits without a enema but they seem to help. And i dont agree with that they will get lodged in the colon if you dont take an enema, I suppose theres a chance for anything but in my opinion not likely.