It's alcohol based. It temporarily overloads the nerve and partially shuts it down. Like they used to do back in the day with a shot of whiskey. Same concept.
Problem is, it damages the nerve by directly exposing it to alcohol too, so if you are trying to save the tooth and/or the nerve, you're looking at a root canal for sure that way. And when the pain comes back, it can be worse than before.
I'm not a dentist, but I've had plenty of dental problems. You're better off, long term, using the stuff from a tube, even if it is more expensive. Works more effectively, for me at least. I use pointy end of the little plastic flossers to apply it, so I only use a tiny bit and it gets exactly where I need it. Toothpick will work too. Q-tips absorb too much of it and it gets wasted. Just put a little dot on the end of a toothpick, and get it directly to where you need it. I've had tubes of that stuff last for weeks.
Arthritis, bursitis, scoliosis, sciatica, hip dysplasia, bipolar disorder, migraines, macular degeneration, and probably some other stuff. And they are shutting down hospital departments all over the state, while I'm on a fixed income.
God, grant me the serenity to accept the things I cannot change, The courage to change the things I can, And the wisdom to know the difference.