I just want to add my experience with Mestinon. It doesn't bother my stomach at all (I take 60mg every three hours), even on an empty stomach. It makes my mouth water a bit, but not to a bothersome degree. If I'm not doing much, I sometimes have muscle twitches (I should probably take it less frequently on an inactive day). These are very small prices to pay for the benefit I derive! No medicine is without risk, but not treating a disease is also risky. It's a matter of balancing risks.
There's a website you can consult that gathers patient experiences with different drugs:
http://www.askapatient.com/rateyourmedicine.htm . Just don't put _too_ much stock in it. People often wrongly assume some symptom is a side-effect of the drug when it's unrelated--and check dosage and reason for taking the drug. Still, it can be useful, taken moderately with a grain of salt.
Abby