When I increased my Mestinon, I had brain fog for about a weak which essentially was followed by a paralysis for about five or so hours. Afterwards, I regain my ability to use my limbs, but both sides of my body were really weak, when only one side use to be.

I was sent to ER and told it was an adverse reaction to Mestinon.

Eventually, I regain my strength on my left side and was placed back on them, but to be on lower doses until my body can accept the medication. Now, I back to taking a higher dosage of Mestinon, and I no longer have the brain fog.