Have you spoke to your doctor about the side effects? I know *nothing* about thiamine or the potential damage to your optic nerve, but it sounds like something I'd talk to my doctor about immediately. ​ EDIT: I'm reading through the Thiamin Protocol. Dr. Schwartz starts Chapter 10 with the following paragraph: ​ >We have several tools that can be used to deal with stuttering and there is a preferred sequence to follow when using them. But first, before beginning, remember to consult with your physician to get clearance. Also, should any undesirable side effects occur, cease taking all supplements immediately and contact your physician.