It's fine to use "as needed" if you understand two things: 1. You may find yourself "crashing" more if you try and skip doses and 2. You need to make sure you aren't "settling" for the improved function IVIG gives if you instead of maximizing that boost with a small dose of mestinon.

You mentioned in a post yesterday that you are having more breathing, chewing and swallowing issues. That would indicate to me that you are not doing well enough to go completely without mestinon, but you may be able to reduce your dose. Only you can determine that one, however.

Good luck!