I have had more SI joint injections than I can count, with and without anesthesia. The doctor will numb the area first, but it you have a lot of pain due to inflammation, you mught go with the anesthesia. Without it will hurt some, but you wont jump off the table. It can last 3 weeks or 3 months and depends on you pinpointing where your pain or trigger points are. Sometimes I mark mine with a pen. I highly recommend getting both sides done at the same time or its like having 2 flat tires but only getting one fixed and driving on the other flat.