Mexiletine safety

*Hi Carter,
Just wondering what advice you have received *

My physicians have not expressed any safety concerns with regard to mexiletine.

Separately, I’ve reviewed the Cardiac Arrhythmia Suppression Trial (CAST) data on my own, for which mexiletine has a received a black box warning, and am comfortable with its findings. CAST looked specifically at the effect of encainide and flecainide on the survival rate of individuals with ventricular arrhythmias who had a myocardial infraction in the 2 years prior. There is no evidence increased mortality risk extends to the broader population without those characteristics.


Thanks for that. Perhaps I am too hopeful but it seems to me that when mexiletine is prescribed for patients who do not have ventricular arrhythmias, then the safety profile is improved.
Has anyone out there had a bad experience with mexiletine, or has anyone heard of anyone with EM who had had a bad experience? Thanks.

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!

I’ve also had occasional heartburn because of mexiletine. I never had heart burn prior to mexiletine therapy. I’ve been taking an H2 blocker (famotidine) with my daily dose of mexiletine for the past 6 months. I take mexiletine now only once a day.

Mexiletine can carry side effects but concerns about the black box warning are generally not applicable to the majority of the population. I believe it is contraindicated in patients with a previous history of myocardial infarctions and congestive heart failure for its rare chance of causing arrhythmias and liver toxicity, respectively. I have not experienced any side effects while taking it for the past 2 years personally and I have a relatively benign arrhythmia myself and my physician has told me that she has no issue with me being on it long-term.

Docs ok’ed mexiletine for me up to 900-1200 mg with regular ekg’s. (Didn’t exactly work for me)
I did have palpitations when starting but went away with time on the drug. My doc took an ekg at the time and ok’ed me to continue. I’ve also had this same phenomenon happen with similar drugs like lidocaine iv, ranexa.