Yesterday morning I decided to start Thiamine and took 4 250 mg tablets at 6 am, Approx. 4hours after my parkinson's hit me like a ton of bricks : generalised muscular tension, giddiness, double vision, anxiety... and I had to lye down, until about 8 hours later these symptoms started to recede and returned to "normal" overnight. Anyone else had unwanted side effects from Vit. b1 ? and at what dose.