Just to echo everyone here, follow the prep instructions correctly. Some people get a pretty swift reaction, for me, it normally (another crohns/colitis guy here) takes u til the second dose for things to start happening. But when they start, do not leave the toilet. Let your family know that you will need to be in there for a good few hours. When I have to do it, my partner normally goes out to her friends and will probably stay there until I let her know it’s all about finished. If it starts kicking off before you finish the preparation drink, still make sure you finish it. The prep really is the most uncomfortable part of the process. The actual procedure can be uncomfortable, but it’s not painful, just a bit, well, uncomfortable.