After a couple months with Mexiletine, here are my conclusions. It worked very well during the first 3-4 weeks. However it does cause stomach issues, which in my case required using Prilosec pretty much continuously to be able to tolerate it. However, the other side effect in my case was anxiety. I have never had any prior experience with anxiety, but the Mex definitely caused it to the point where it was really intolerable. I've reduced my dosage of Mex to about 100mg/day (original dose was 400mg/day) and even at this level I have to take a break every few days, otherwise I start feeling noticeable anxiety. It's really a shame, as it was pretty helpful with PN in my case. Needless to say, I am a bit disappointed.