genjutsu messes with the five senses; sight, hearing, smell, taste, and touch. it can't do any actual physical damage. from what we've seen tsukuyomi is aimed for the the opponents' hearing, sight, and touch. i don't know about smell and touch since that's not clearly shown. it didn't do any physical damage to the actual body but it made kakashi's mind think that the body was stabbed for however long it was.