Elle,

I'm negative on all the tests for MG and was clinically dx'd. At my first follow up apt, my doc asked how everything was and when I said 'so much better I can hardly believe it' she replied:
Well you definitely have MG cause your body couldn't handle that much Mestinon if you didn't.

So I'm assuming that if Mestinon is taken by a healthy person - the overdose symptoms would be exhibited - - and yes too much can be dangerous. But the drug is short acting and does not build in your system..it only lasts about four hours.

So if you have had no (serious) overdose symptoms, I doubt there is anything to be concerned about.