There is a thread on the MGA forum here in the UK where someone is experiencing symptoms of an allergic reaction to Mestinon.

They have a rash when they take the mestinon and some people find that they can't tolerate it due to the allergic reaction and not the side effects.

Allergic reaction - swelling of mouth, lips and tongue etc, skin rash

Side effects (although they can be horribly severe) - nausea, vommiting, the runs, stomach cramps, drooling (I've had all these! LOL)

The ingredient that people tend to be allergic to is the BROMIDE.

I would contact your Dr if your mouth/ lips have swelled its not a good sign and your next reaction could be more severe.

Good luck

Love
Rach