I have tried mexiletine and while my experience wasn’t horrible I did have some side effects. Really both side effects were intensified by mexiletine as I have had both heart palpitations and heart burn prior, just not to that degree or as frequent. I continued on with the medication in hopes of the relief others have found but after 5 months there was no change for me in either the degree of the flares or the frequency of the flares. If you have concerns you could ask for a cardiac EKG in advance to trialing the medication. I didn’t ask and surprisingly my Dr. didn’t request one prior to prescribing (It took me a long time to convince him - he was very much against it at first, many Dr’s are). I wish you the best! I hope when you obtain this medication it does wonders for you!