Some people say they go away, some say they don't.
At the moment the tool I use the most is the 15 minute rule. You feel like SI, you choose either to do it or not, it's entirely up to you. If you choose to wait, you time yourself 15mins and do something distracting and/or soothing. If, after 15 minutes you still have the urge, you get to choose again. It's always in your power to do it or not to. No one can stop you it's your choice to make either way.
This has helped me many times not to SI and sometimes I have chosen to. It's in my power.