Sertraline has almost entirely fixed my panic disorder.

It had no obvious cause and months of therapy had no impact. Within a few days of taking sertraline, it was essentially cured. I still get anxious from time to time but I'm able to live a completely normal life again. I had a few side effects (GI especially) for a few weeks but now the only side effect I have is I yawn a lot more, which is pretty tame.

I'm a big believer in the gut-brain connection and wonder if maybe it was something to do with the drug's GI effects that helped, but ultimately I have no idea and it doesn't really matter.