Snoel, No, it's not an adverse reaction to Mestinon. Trigger finger is caused by an inflammatory process, which itself has many causes.

Frequency in Mestinon dosing, with a smaller dose (90 - 110 mg), is often a better way to go. Instead of every 4 hours, every 2-1/2 to 3 hours is common. But, of course, talk to your neuro first before making any changes.

You're basically flooding your neuromuscular junction with too much acetylcholine. I'm surprised you haven't had a cholinergic crisis by now.

Annie