Depends on how you do it. The most correct way and highest chance for it to work:
1. Fasting for 12 hours at least, you can drink just water.
2. Taking in your antiemetic pill (has to be dopamine blocker, like metoclopramide) against puking 2 hours before SN
3. Taking in your benzodiazepines (alprazolam recommended) an hour before SN
4. Finally, drinking the SN (25mg SN mixed in water, purity of the SN should be 98% minimum)
5. Waiting till you lose consciousness.
If you did everything correctly, you shouldn't wake up after passing out. Making it a successful ctb.